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LAN8720/LAN8720i
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
PRODUCT FEATURES
Highlights
Single-Chip Ethernet Physical Layer Transceiver (PHY) Comprehensive flexPWR(R) Technology
-- -- -- -- Flexible Power Management Architecture Power savings of up to 40% compared to competition LVCMOS Variable I/O voltage range: +1.6V to +3.6V Integrated 1.2V regulator
Datasheet
Key Benefits
High-Performance 10/100 Ethernet Transceiver
-- -- -- -- -- -- -- -- -- -- -- Compliant with IEEE802.3/802.3u (Fast Ethernet) Compliant with ISO 802-3/IEEE 802.3 (10BASE-T) Loop-back modes Auto-negotiation Automatic polarity detection and correction Link status change wake-up detection Vendor specific register functions
HP Auto-MDIX support Miniature 24 pin QFN lead-free RoHS compliant package (4 x 4 x 0.85mm height).
Power and I/Os
Various low power modes Integrated power-on reset circuit Two status LED outputs Latch-Up Performance Exceeds 150mA per EIA/JESD 78, Class II -- May be used with a single 3.3V supply
Target Applications
Set-Top Boxes Networked Printers and Servers Test Instrumentation LAN on Motherboard Embedded Telecom Applications Video Record/Playback Systems Cable Modems/Routers DSL Modems/Routers Digital Video Recorders IP and Video Phones Wireless Access Points Digital Televisions Digital Media Adaptors/Servers Gaming Consoles POE Applications
Advanced Features
-- Able to use a low cost 25Mhz crystal for the lowest eBOM
Packaging
-- 24-pin QFN (4x4 mm) Lead-Free RoHS Compliant package with RMII
Environmental
-- Extended Commercial Temperature Range (0C to +85C) -- Industrial Temperature Range (-40C to +85C) version available (LAN8720i)
SMSC LAN8720/LAN8720i
Revision 1.0 (05-28-09)
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
ORDER NUMBER(S):
LAN8720A-CP-TR FOR 24-PIN, QFN LEAD-FREE ROHS COMPLIANT PACKAGE (0 TO +85C TEMP) LAN8720Ai-CP-TR FOR 24-PIN, QFN LEAD-FREE ROHS COMPLIANT PACKAGE (-40 TO +85C TEMP)
Reel Size is 4000
80 ARKAY DRIVE, HAUPPAUGE, NY 11788 (631) 435-6000, FAX (631) 273-3123 Copyright (c) 2009 SMSC or its subsidiaries. All rights reserved. Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete information sufficient for construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no responsibility is assumed for inaccuracies. SMSC reserves the right to make changes to specifications and product descriptions at any time without notice. Contact your local SMSC sales office to obtain the latest specifications before placing your product order. The provision of this information does not convey to the purchaser of the described semiconductor devices any licenses under any patent rights or other intellectual property rights of SMSC or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated version of SMSC's standard Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or errors known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon request. SMSC products are not designed, intended, authorized or warranted for use in any life support or other application where product failure could cause or contribute to personal injury or severe property damage. Any and all such uses without prior written approval of an Officer of SMSC and further testing and/or modification will be fully at the risk of the customer. Copies of this document or other SMSC literature, as well as the Terms of Sale Agreement, may be obtained by visiting SMSC's website at http://www.smsc.com. SMSC is a registered trademark of Standard Microsystems Corporation ("SMSC"). Product names and company names are the trademarks of their respective holders. SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND ALL WARRANTIES ARISING FROM ANY COURSE OF DEALING OR USAGE OF TRADE. IN NO EVENT SHALL SMSC BE LIABLE FOR ANY DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES; OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF THE FORM OF ACTION, WHETHER BASED ON CONTRACT; TORT; NEGLIGENCE OF SMSC OR OTHERS; STRICT LIABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT ANY REMEDY OF BUYER IS HELD TO HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHETHER OR NOT SMSC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Revision 1.0 (05-28-09)
2
SMSC LAN8720/LAN8720i
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Table of Contents
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.1 1.2 1.3 General Terms and Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Architectural Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 2 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1 Package Pin-out Diagram and Signal Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 3 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 3.2 3.3 3.4 3.5 3.6 3.7 MAC Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LED Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Management Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10/100 Line Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Analog Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 15 16 16 17 17 17
Chapter 4 Architecture Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 4.2 Top Level Functional Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100Base-TX Transmit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1 100M Transmit Data Across the MII/RMII Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 4B/5B Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3 Scrambling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4 NRZI and MLT3 Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.5 100M Transmit Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.6 100M Phase Lock Loop (PLL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100Base-TX Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 100M Receive Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.2 Equalizer, Baseline Wander Correction and Clock and Data Recovery . . . . . . . . . . . . . 4.3.3 NRZI and MLT-3 Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4 Descrambling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.5 Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.6 5B/4B Decoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7 Receive Data Valid Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.8 Receiver Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.9 100M Receive Data Across the MII/RMII Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Base-T Transmit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.1 10M Transmit Data Across the MII/RMII Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.2 Manchester Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.3 10M Transmit Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Base-T Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.1 10M Receive Input and Squelch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.2 Manchester Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.3 10M Receive Data Across the MII/RMII Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.4 Jabber Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MAC Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6.1 RMII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reference Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.1 REF_CLK In Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.2 REF_CLK OUT Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
4.3
4.4
4.5
4.6 4.7
18 18 18 19 20 20 20 21 21 21 21 22 22 22 22 22 23 23 23 23 24 24 24 24 24 25 25 25 25 26 27 27
SMSC LAN8720/LAN8720i
Revision 1.0 (05-28-09)
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
4.8
4.9 4.10 4.11 4.12 4.13 4.14
Auto-negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.1 Parallel Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.2 Re-starting Auto-negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.3 Disabling Auto-negotiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.4 Half vs. Full Duplex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP Auto-MDIX Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . nINTSEL Strapping and LED Polarity Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REGOFF and LED Polarity Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PHY Address Strapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Variable Voltage I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transceiver Management Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.14.1 Serial Management Interface (SMI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29 31 31 31 31 31 32 33 34 34 34 34
Chapter 5 SMI Register Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.1 5.2 SMI Register Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interrupt Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.1 Primary Interrupt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.2 Alternate Interrupt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Miscellaneous Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Carrier Sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Collision Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.3 Isolate Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.4 Link Integrity Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.5 Power-Down modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.6 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.7 LED Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.8 Loopback Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.9 Configuration Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 48 48 49 49 49 50 50 50 50 51 51 51 53
5.3
Chapter 6 AC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.1 6.2 Serial Management Interface (SMI) Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RMII 10/100Base-TX/RX Timings (50MHz REF_CLK IN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.1 RMII 100Base-T TX/RX Timings (50MHz REF_CLK IN). . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2 RMII 10Base-T TX/RX Timings (50MHz REF_CLK IN). . . . . . . . . . . . . . . . . . . . . . . . . . RMII 10/100Base-TX/RX Timings (50MHz REF_CLK OUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3.1 RMII 100Base-T TX/RX Timings (50MHz REF_CLK OUT). . . . . . . . . . . . . . . . . . . . . . . 6.3.2 RMII 10Base-T TX/RX Timings (50MHz REF_CLK OUT). . . . . . . . . . . . . . . . . . . . . . . . RMII CLKIN Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reset Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Clock Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 56 56 58 60 60 62 63 64 65
6.3
6.4 6.5 6.6
Chapter 7 DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
7.1 DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Maximum Guaranteed Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.2 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.3 Power Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.4 DC Characteristics - Input and Output Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 66 67 67 70
Chapter 8 Application Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
8.1 Application Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.1 RMII Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.2 Power Supply Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1.3 Twisted-Pair Interface Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Magnetics Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
8.2
73 73 74 74 75
Revision 1.0 (05-28-09)
SMSC LAN8720/LAN8720i
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Chapter 9 Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Chapter 10 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
SMSC LAN8720/LAN8720i
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Revision 1.0 (05-28-09)
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
List of Figures
Figure 1.1 Figure 1.2 Figure 2.1 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 4.9 Figure 4.10 Figure 4.11 Figure 5.1 Figure 5.2 Figure 5.3 Figure 6.1 Figure 6.2 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Figure 6.8 Figure 6.9 Figure 6.10 Figure 8.1 Figure 8.2 Figure 8.3 Figure 8.4 Figure 8.5 Figure 9.1 Figure 9.1 Figure 9.2 LAN8720/LAN8720i System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LAN8720/LAN8720i Architectural Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LAN8720/LAN8720i 24-QFN Pin Assignments (TOP VIEW). . . . . . . . . . . . . . . . . . . . . . . . . 100Base-TX Data Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Receive Data Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Relationship Between Received Data and Specific MII Signals . . . . . . . . . . . . . . . . . . . . . . External 50MHz clock sources the REF_CLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LAN8720 sources REF_CLK from a 25MHz crystal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LAN8720 Sources REF_CLK from External 25MHz Source . . . . . . . . . . . . . . . . . . . . . . . . . Direct Cable Connection vs. Cross-over Cable Connection . . . . . . . . . . . . . . . . . . . . . . . . . nINTSEL Strapping on LED2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REGOFF Configuration on LED1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MDIO Timing and Frame Structure - READ Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MDIO Timing and Frame Structure - WRITE Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Near-end Loopback Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Far Loopback Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Connector Loopback Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SMI Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100M RMII Receive Timing Diagram (50MHz REF_CLK IN). . . . . . . . . . . . . . . . . . . . . . . . . 100M RMII Transmit Timing Diagram (50MHz REF_CLK IN) . . . . . . . . . . . . . . . . . . . . . . . . 10M RMII Receive Timing Diagram (50MHz REF_CLK IN). . . . . . . . . . . . . . . . . . . . . . . . . . 10M RMII Transmit Timing Diagram (50MHz REF_CLK IN) . . . . . . . . . . . . . . . . . . . . . . . . . 100M RMII Receive Timing Diagram (50MHz REF_CLK OUT). . . . . . . . . . . . . . . . . . . . . . . 100M RMII Transmit Timing Diagram (50MHz REF_CLK OUT) . . . . . . . . . . . . . . . . . . . . . . 10M RMII Receive Timing Diagram (50MHz REF_CLK OUT). . . . . . . . . . . . . . . . . . . . . . . . 10M RMII Transmit Timing Diagram (50MHz REF_CLK OUT) . . . . . . . . . . . . . . . . . . . . . . . Reset Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Simplified Application Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High-Level System Diagram for Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High-Level System Diagram for Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Copper Interface Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Copper Interface Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LAN8720/LAN8720i-EZK 24-QFN Package Outline, 4 x 4 x 0.9 mm Body (Lead-Free) . . . . QFN, 4x4 Taping Dimensions and Part Orientation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reel Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 11 12 18 21 23 27 28 29 32 33 33 35 35 52 52 53 55 56 57 58 59 60 61 62 63 64 73 74 74 74 74 76 77 78
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SMSC LAN8720/LAN8720i
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
List of Tables
Table 2.1 LAN8720/LAN8720i 24-PIN QFN Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.1 Buffer Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.2 RMII Signals 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.3 LED Signals 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.4 Management Signals 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.5 General Signals 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.6 10/100 Line Interface Signals 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.7 Analog References 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 3.8 Power Signals 24-QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 4.1 4B/5B Code Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 4.2 REFCLK Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 4.3 LED2/nINTSEL Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.1 Control Register: Register 0 (Basic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.2 Status Register: Register 1 (Basic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.3 PHY ID 1 Register: Register 2 (Extended) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.4 PHY ID 2 Register: Register 3 (Extended) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.5 Auto-Negotiation Advertisement: Register 4 (Extended) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.6 Auto-Negotiation Link Partner Base Page Ability Register: Register 5 (Extended) . . . . . . . . . Table 5.7 Auto-Negotiation Expansion Register: Register 6 (Extended). . . . . . . . . . . . . . . . . . . . . . . . . Table 5.8 Register 15 (Extended) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.9 Silicon Revision Register 16: Vendor-Specific. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.10 Mode Control/ Status Register 17: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.11 Special Modes Register 18: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.12 Register 24: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.13 Register 25: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.14 Symbol Error Counter Register 26: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.15 Special Control/Status Indications Register 27: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . Table 5.16 Special Internal Testability Control Register 28: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . Table 5.17 Interrupt Source Flags Register 29: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.18 Interrupt Mask Register 30: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.19 PHY Special Control/Status Register 31: Vendor-Specific . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.20 SMI Register Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.21 Register 0 - Basic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.22 Register 1 - Basic Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.23 Register 2 - PHY Identifier 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.24 Register 3 - PHY Identifier 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.25 Register 4 - Auto Negotiation Advertisement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.26 Register 5 - Auto Negotiation Link Partner Ability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.27 Register 6 - Auto Negotiation Expansion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.28 Register 16 - Silicon Revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.29 Register 17 - Mode Control/Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.30 Register 18 - Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.31 Register 26 - Symbol Error Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.33 Register 28 - Special Internal Testability Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.34 Register 29 - Interrupt Source Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.32 Register 27 - Special Control/Status Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.35 Register 30 - Interrupt Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.36 Register 31 - PHY Special Control/Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.37 Interrupt Management Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.38 Alternative Interrupt System Management Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.39 MODE[2:0] Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 5.40 Pin Names for Mode Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.1 SMI Timing Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMSC LAN8720/LAN8720i 7
13 14 15 15 16 16 17 17 17 19 26 32 36 36 36 36 37 37 37 37 37 38 38 38 38 38 39 39 39 39 39 40 41 41 42 42 42 43 44 44 44 45 45 46 46 46 47 47 48 49 54 54 55
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DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Table 6.2 100M RMII Receive Timing Values (50MHz REF_CLK IN). . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.3 100M RMII Transmit Timing Values (50MHz REF_CLK IN) . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.4 10M RMII Receive Timing Values (50MHz REF_CLK IN). . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.5 10M RMII Transmit Timing Values (50MHz REF_CLK IN) . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.6 100M RMII Receive Timing Values (50MHz REF_CLK OUT). . . . . . . . . . . . . . . . . . . . . . . . . Table 6.7 100M RMII Transmit Timing Values (50MHz REF_CLK OUT) . . . . . . . . . . . . . . . . . . . . . . . . Table 6.8 10M RMII Receive Timing Values (50MHz REF_CLK OUT). . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.9 10M RMII Transmit Timing Values (50MHz REF_CLK OUT) . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.10 RMII CLKIN (REF_CLK) Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.11 Reset Timing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 6.12 LAN8720/LAN8720i Crystal Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.1 Maximum Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.2 ESD and LATCH-UP Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.3 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.4 Power Consumption Device Only (REF_CLK IN MODE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.5 Power Consumption Device Only (50MHz REF_CLK OUT MODE) . . . . . . . . . . . . . . . . . . . . Table 7.6 RMII Bus Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.7 LAN Interface Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.8 LED Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.9 Configuration Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.10 General Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.11 Internal Pull-Up / Pull-Down Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.12 100Base-TX Transceiver Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 7.13 10BASE-T Transceiver Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 9.1 24 Terminal QFN Package Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 10.1 Customer Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
56 57 58 59 60 61 62 63 63 64 65 66 66 67 68 68 70 71 71 71 71 71 72 72 76 79
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SMSC LAN8720/LAN8720i
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Chapter 1 Introduction
1.1 General Terms and Conventions
The following is list of the general terms used in this document:
BYTE FIFO MAC MII RMIITM N/A X RESERVED
8-bits First In First Out buffer; often used for elasticity buffer Media Access Controller Media Independent Interface Reduced Media Independent InterfaceTM Not Applicable Indicates that a logic state is "don't care" or undefined. Refers to a reserved bit field or address. Unless otherwise noted, reserved bits must always be zero for write operations. Unless otherwise noted, values are not guaranteed when reading reserved bits. Unless otherwise noted, do not read or write to reserved addresses. Serial Management Interface
SMI
1.2
General Description
The LAN8720/LAN8720i is a low-power 10BASE-T/100BASE-TX physical layer (PHY) transceiver that transmits and receives on unshielded twisted-pair cable. A typical system application is shown in Figure 1.2. It is available in both extended commercial and industrial temperature operating versions. The LAN8720/LAN8720i interfaces to the MAC layer using a variable voltage digital interface via the RMII interface. The digital interface pins are tolerant to 3.6V. The LAN8720/LAN8720i implements Auto-Negotiation to automatically determine the best possible speed and duplex mode of operation. HP Auto-MDIX support allows using a direct connect LAN cable, or a cross-over path cable. The LAN8720 referenced throughout this document applies to both the extended commercial temperature and industrial temperature components. The LAN8720i refers to only the industrial temperature component.
SMSC LAN8720/LAN8720i
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DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
10/100 Ethernet MAC
RMII
MDI
Transformer
RJ45
LAN8720
Ethernet Transceiver
LED Status
MODE
Crystal or Clock Osc
Figure 1.1 LAN8720/LAN8720i System Block Diagram
1.3
Architectural Overview
The LAN8720/LAN8720i is compliant with IEEE 802.3-2005 standards (RMII Pins tolerant to 3.6V) and supports both IEEE 802.3-2005 compliant and vendor-specific register functions. It contains a fullduplex 10-BASE-T/100BASE-TX transceiver and supports 10-Mbps (10BASE-T) operation, and 100Mbps (100BASE-TX) operation. The LAN8720/LAN8720i can be configured to operate on a single 3.3V supply utilizing an integrated 3.3V to 1.2V linear regulator. An option is available to disable the linear regulator to optimize system designs that have a 1.2V power supply available. This allows for the use of a high efficiency external regulator for lower system power dissipation.
1.3.1
Configuration
The LAN8720 will begin normal operation following reset, and no register access is required. The initial configuration may be selected with configuration pins as described in Section 5.3.9. In addition, register-selectable configuration options may be used to further define the functionality of the transceiver. For example, the device can be set to 10BASE-T only. The LAN8720 supports both IEEE 802.3-2005 compliant and vendor-specific register functions.
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SMSC LAN8720/LAN8720i
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
MODE0 MODE1 MODE2 nRST
MODE Control Reset Control
AutoNegotiation
10M Tx Logic
10M Transmitter
HP Auto-MDIX
TXP / TXN RXP / RXN
Transmit Section Management Control 100M Tx Logic 100M Transmitter MDIX Control
SMI
TXD[1:0] TXEN
100M Rx Logic
RXD[1:0] RXER
DSP System: Clock Data Recovery Equalizer
Analog-toDigital
PLL Interrupt Generator
XTAL1/CLKIN XTAL2 nINT
RMII Logic
Receive Section 10M Rx Logic 10M PLL
100M PLL LED Circuitry Squelch & Filters Central Bias PHY Address Latches
LED1 LED2
CRS_DV MDC MDIO
RBIAS
PHYAD0
Figure 1.2 LAN8720/LAN8720i Architectural Overview
SMSC LAN8720/LAN8720i
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Revision 1.0 (05-28-09)
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Chapter 2 Pin Configuration
2.1 Package Pin-out Diagram and Signal Table
24
23
22
21
20
TXN
VDD2A LED2/nINTSEL LED1/REGOFF XTAL2 XTAL1/CLKIN VDDCR
1 2 3 4 5 6 7 8 9
19 18
VDD1A
RBIAS
RXN
RXP
TXP
TXD1 TXD0 TXEN nRST nINT/REFCLKO MDC
SMSC LAN8720/ LAN8720i 24 PIN QFN (Top View)
VSS 10 11 12 MDIO
17 16 15 14 13
Figure 2.1 LAN8720/LAN8720i 24-QFN Pin Assignments (TOP VIEW)
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12
CRS_DV/MODE2
RXER/PHYAD0
RXD1/MODE1
RXD0/MDE0
VDDIO
SMSC LAN8720/LAN8720i
DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Table 2.1 LAN8720/LAN8720i 24-PIN QFN Pinout PIN NO. 1 2 3 4 5 6 7 8 9 10 11 12 PIN NAME VDD2A LED2/nINTSEL LED1/REGOFF XTAL2 XTAL1/CLKIN VDDCR RXD1/MODE1 RXD0/MODE0 VDDIO RXER/PHYAD0 CRS_DV/MODE2 MDIO PIN NO. 13 14 15 16 17 18 19 20 21 22 23 24 PIN NAME MDC nINT/REFCLKO nRST TXEN TXD0 TXD1 VDD1A TXN TXP RXN RXP RBIAS
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DATASHEET
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Chapter 3 Pin Description
This chapter describes the signals on each pin. When a lower case "n" is used at the beginning of the signal name, it indicates that the signal is active low. For example, nRST indicates that the reset signal is active low. The buffer type for each signal is indicated in the TYPE column, and a description of the buffer types is provided in Table 3.1. Table 3.1 Buffer Types BUFFER TYPE I8 O8 IOD8 IPU Note 3.1 IPD Note 3.1 IOPU Note 3.1 IOPD Note 3.1 AI AIO ICLK OCLK P Note 3.1 Input. Output with 8mA sink and 8mA source. Input/Open-drain output with 8mA sink. Input with 67k (typical) internal pull-up. Input with 67k (typical) internal pull-down. Input/Output with 67k (typical) internal pull-up. Output has 8mA sink and 8mA source. Input/Output with 67k (typical) internal pull-down. Output has 8mA sink and 8mA source. Analog input Analog bi-directional Crystal oscillator input pin Crystal oscillator output pin Power pin Unless otherwise noted in the pin description, internal pull-up and pull-down resistors are always enabled. The internal pull-up and pull-down resistors prevent unconnected inputs from floating, and must not be relied upon to drive signals external to LAN8720/LAN8720i. When connected to a load that must be pulled high or low, an external resistor must be added. DESCRIPTION
Note: The digital signals are not 5V tolerant.They are variable voltage from +1.6V to +3.6V, as shown in Table 7.1.
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3.1
MAC Interface Signals
Table 3.2 RMII Signals 24-QFN
SIGNAL NAME TXD0 TXD1 TXEN RXD0/ MODE0
24-QFN PIN # 17 18 16 8
TYPE I8 I8 IPD IOPU
DESCRIPTION Transmit Data 0: The MAC transmits data to the PHY using this signal in all modes. Transmit Data 1: The MAC transmits data to the PHY using this signal in all modes Transmit Enable: Indicates that valid data is presented on the TXD[1:0] signals, for transmission. Receive Data 0: Bit 0 of the 4 data bits that are sent by the PHY in the receive path. PHY Operating Mode Bit 0: set the default MODE of the PHY. See Section 5.3.9.2 for information on the MODE options.
RXD1/ MODE1
7
IOPU
Receive Data 1: Bit 1 of the 4 data bits that are sent by the PHY in the receive path. PHY Operating Mode Bit 1: set the default MODE of the PHY. See Section 5.3.9.2 for information on the MODE options.
RXER/ PHYAD0
10
IOPD
Receive Error: Asserted to indicate that an error was detected somewhere in the frame presently being transferred from the PHY. The RXER signal is optional in RMII Mode. This signal is mux'd with PHYAD0 See Section 5.3.9.1 for information on the ADDRESS options.
CRS_DV/ MODE2
11
IOPU
RMII Mode CRS_DV (Carrier Sense/Receive Data Valid) Asserted to indicate when the receive medium is non-idle. When a 10BT packet is received, CRS_DV is asserted, but RXD[1:0] is held low until the SFD byte (10101011) is received. In 10BT, half-duplex mode, transmitted data is not looped back onto the receive data pins, per the RMII standard. PHY Operating Mode Bit 2: set the default MODE of the PHY. See Section 5.3.9.2 for information on the MODE options.
3.2
LED Signals
Table 3.3 LED Signals 24-QFN
SIGNAL NAME LED1/ REGOFF
24-QFN PIN # 3
TYPE IOPD
DESCRIPTION LED1 - Link activity LED Indication. See Section 5.3.7 for a description of LED modes. Regulator Off: This pin may be used to configure the internal 1.2V regulator off. As described in Section 4.11, this pin is sampled during the power-on sequence to determine if the internal regulator should turn on. When the regulator is disabled, external 1.2V must be supplied to VDDCR. When LED1/REGOFF is pulled high to VDD2A with an external resistor, the internal regulator is disabled. When LED1/REGOFF is floating or pulled low, the internal regulator is enabled (default).
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Table 3.3 LED Signals 24-QFN (continued) SIGNAL NAME LED2/ nINTSEL 24-QFN PIN # 2
TYPE IOPU
DESCRIPTION LED2 - Link speed LED Indication. See Section 5.3.7 for a description of LED modes. nINTSEL: On power-up or external reset, the mode of the nINT/REFCLKO pin is selected. See Section 4.10 for additional detail. When LED2/nINTSEL is floated or pulled to VDD2A, nINT is selected for operation on pin nINT/REFCLKO (default). When LED2/nINTSEL is pulled low to VSS through a resistor, REFCLKO is selected for operation on pin nINT/REFCLKO.
3.3
Management Signals
Table 3.4 Management Signals 24-QFN
SIGNAL NAME MDIO MDC
24-QFN PIN # 12 13
TYPE IOD8 I8
DESCRIPTION Management Data Input/OUTPUT: Serial management data input/output. Management Clock: Serial management clock.
3.4
General Signals
Table 3.5 General Signals 24-QFN
SIGNAL NAME nINT/ REFCLKO
24-QFN PIN # 14
TYPE IOPU
DESCRIPTION nINT - Active low interrupt output. Place an external resistor pull-up to VDDIO. REFCLKO - 50MHz clock derived from the 25MHz crystal oscillator. See Section 4.7.2 for additional detail. See DESCRIPTION of pin 2: LED2 - Link speed LED Indication. This signal is mux'd with REFCLKO.
XTAL1/ CLKIN XTAL2 nRST
5 4 15
ICLK OCL K IOPU
Clock Input: Crystal connection or external clock input. Clock Output: Crystal connection. Float this pin when an external clock is driven to XTAL1/CLKIN. External Reset: Input of the system reset. This signal is active LOW.
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3.5
10/100 Line Interface Signals
Table 3.6 10/100 Line Interface Signals 24-QFN
SIGNAL NAME TXP TXN RXP RXN
24-QFN PIN # 21 20 23 22
TYPE AIO AIO AIO AIO
DESCRIPTION Transmit/Receive Positive Channel 1. Transmit/Receive Negative Channel 1. Transmit/Receive Positive Channel 2. Transmit/Receive Negative Channel 2.
3.6
Analog Reference
Table 3.7 Analog References 24-QFN
SIGNAL NAME RBIAS
24-QFN PIN # 24
TYPE AI
DESCRIPTION External 1% Bias Resistor. Requires an 12.1k resistor to ground connected as described in the Analog Layout Guidelines. The nominal voltage is 1.2V and therefore the resistor will dissipate approximately 1mW of power.
3.7
Power Signals
Table 3.8 Power Signals 24-QFN
SIGNAL NAME VDDIO VDDCR
24-QFN PIN # 9 6
TYPE P P
DESCRIPTION +1.6V to +3.6V Variable I/O Pad Power +1.2V (Core voltage) - 1.2V for digital circuitry on chip. Supplied by the onchip regulator unless configured for regulator off mode using the RXCLK/REGOFF pin. A 1uF decoupling capacitor to ground should be used on this pin when using the internal 1.2V regulator. +3.3V Analog Port Power to Channel 1. +3.3V Analog Port Power to Channel 2 and to internal regulator. The flag must be connected to the ground plane with a via array under the exposed flag. This is the ground connection for the IC.
VDD1A VDD2A VSS
19 1 FLAG
P P GND
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Chapter 4 Architecture Details
4.1 Top Level Functional Architecture
Functionally, the transceiver can be divided into the following sections: 100Base-TX transmit and receive 10Base-T transmit and receive RMII interface to the controller Auto-negotiation to automatically determine the best speed and duplex possible Management Control to read status registers and write control registers
PLL MAC
Ref_CLK RMII 50Mhz by 2 bits
RMII
25MHz by 4 bits
4B/5B Encoder
25MHz by 5 bits
Scrambler and PISO
125 Mbps Serial
NRZI Converter
NRZI
MLT-3 Converter
MLT-3
Tx Driver
MLT-3
Magnetics
MLT-3
RJ45
MLT-3
CAT-5
Figure 4.1 100Base-TX Data Path
4.2
100Base-TX Transmit
The data path of the 100Base-TX is shown in Figure 4.1. Each major block is explained below.
4.2.1
100M Transmit Data Across the MII/RMII Interface
For MII, the MAC controller drives the transmit data onto the TXD bus and asserts TXEN to indicate valid data. The data is latched by the transceiver's MII block on the rising edge of TXCLK. The data is in the form of 4-bit wide 25MHz data. For RMII, the MAC controller drives the transmit data onto the TXD bus and asserts TXEN to indicate valid data. The data is latched by the transceiver's RMII block on the rising edge of REF_CLK. The data is in the form of 2-bit wide 50MHz data.
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4.2.2
4B/5B Encoding
The transmit data passes from the MII block to the 4B/5B encoder. This block encodes the data from 4-bit nibbles to 5-bit symbols (known as "code-groups") according to Table 4.1. Each 4-bit data-nibble is mapped to 16 of the 32 possible code-groups. The remaining 16 code-groups are either used for control information or are not valid. The first 16 code-groups are referred to by the hexadecimal values of their corresponding data nibbles, 0 through F. The remaining code-groups are given letter designations with slashes on either side. For example, an IDLE code-group is /I/, a transmit error code-group is /H/, etc. The encoding process may be bypassed by clearing bit 6 of register 31. When the encoding is bypassed the 5th transmit data bit is equivalent to TXER. Note that encoding can be bypassed only when the MAC interface is configured to operate in MII mode. Table 4.1 4B/5B Code Table
CODE GROUP 11110 01001 10100 10101 01010 01011 01110 01111 10010 10011 10110 10111 11010 11011 11100 11101 11111 11000 10001 01101
SYM 0 1 2 3 4 5 6 7 8 9 A B C D E F I J K T IDLE 0 1 2 3 4 5 6 7 8 9 A B C D E F
RECEIVER INTERPRETATION 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 DATA 0 1 2 3 4 5 6 7 8 9 A B C D E F
TRANSMITTER INTERPRETATION 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 DATA
Sent after /T/R until TXEN Sent for rising TXEN Sent for rising TXEN Sent for falling TXEN
First nibble of SSD, translated to "0101" following IDLE, else RXER Second nibble of SSD, translated to "0101" following J, else RXER First nibble of ESD, causes de-assertion of CRS if followed by /R/, else assertion of RXER
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Table 4.1 4B/5B Code Table (continued) CODE GROUP 00111 RECEIVER INTERPRETATION Second nibble of ESD, causes deassertion of CRS if following /T/, else assertion of RXER Transmit Error Symbol INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV INVALID, RXER if during RXDV TRANSMITTER INTERPRETATION Sent for falling TXEN
SYM R
00100 00110 11001 00000 00001 00010 00011 00101 01000 01100 10000
H V V V V V V V V V V
Sent for rising TXER INVALID INVALID INVALID INVALID INVALID INVALID INVALID INVALID INVALID INVALID
4.2.3
Scrambling
Repeated data patterns (especially the IDLE code-group) can have power spectral densities with large narrow-band peaks. Scrambling the data helps eliminate these peaks and spread the signal power more uniformly over the entire channel bandwidth. This uniform spectral density is required by FCC regulations to prevent excessive EMI from being radiated by the physical wiring. The seed for the scrambler is generated from the transceiver address, PHYAD[4:0], ensuring that in multiple-transceiver applications, such as repeaters or switches, each transceiver will have its own scrambler sequence. The scrambler also performs the Parallel In Serial Out conversion (PISO) of the data.
4.2.4
NRZI and MLT3 Encoding
The scrambler block passes the 5-bit wide parallel data to the NRZI converter where it becomes a serial 125MHz NRZI data stream. The NRZI is encoded to MLT-3. MLT3 is a tri-level code where a change in the logic level represents a code bit "1" and the logic output remaining at the same level represents a code bit "0".
4.2.5
100M Transmit Driver
The MLT3 data is then passed to the analog transmitter, which drives the differential MLT-3 signal, on outputs TXP and TXN, to the twisted pair media across a 1:1 ratio isolation transformer. The 10BaseT and 100Base-TX signals pass through the same transformer so that common "magnetics" can be used for both. The transmitter drives into the 100 impedance of the CAT-5 cable. Cable termination and impedance matching require external components.
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4.2.6
100M Phase Lock Loop (PLL)
The 100M PLL locks onto reference clock and generates the 125MHz clock used to drive the 125 MHz logic and the 100Base-Tx Transmitter.
PLL MAC
Ref_CLK RMII 50Mhz by 2 bits
RMII
25MHz by 4 bits
4B/5B Encoder
25MHz by 5 bits
Scrambler and PISO
125 Mbps Serial
NRZI Converter
NRZI
MLT-3 Converter
MLT-3
Tx Driver
MLT-3
Magnetics
MLT-3
RJ45
MLT-3
CAT-5
Figure 4.2 Receive Data Path
4.3
100Base-TX Receive
The receive data path is shown in Figure 4.2. Detailed descriptions are given below.
4.3.1
100M Receive Input
The MLT-3 from the cable is fed into the transceiver (on inputs RXP and RXN) via a 1:1 ratio transformer. The ADC samples the incoming differential signal at a rate of 125M samples per second. Using a 64-level quanitizer it generates 6 digital bits to represent each sample. The DSP adjusts the gain of the ADC according to the observed signal levels such that the full dynamic range of the ADC can be used.
4.3.2
Equalizer, Baseline Wander Correction and Clock and Data Recovery
The 6 bits from the ADC are fed into the DSP block. The equalizer in the DSP section compensates for phase and amplitude distortion caused by the physical channel consisting of magnetics, connectors, and CAT- 5 cable. The equalizer can restore the signal for any good-quality CAT-5 cable between 1m and 150m. If the DC content of the signal is such that the low-frequency components fall below the low frequency pole of the isolation transformer, then the droop characteristics of the transformer will become significant and Baseline Wander (BLW) on the received signal will result. To prevent corruption of the received data, the transceiver corrects for BLW and can receive the ANSI X3.263-1995 FDDI TP-PMD defined "killer packet" with no bit errors. The 100M PLL generates multiple phases of the 125MHz clock. A multiplexer, controlled by the timing unit of the DSP, selects the optimum phase for sampling the data. This is used as the received recovered clock. This clock is used to extract the serial data from the received signal.
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4.3.3
NRZI and MLT-3 Decoding
The DSP generates the MLT-3 recovered levels that are fed to the MLT-3 converter. The MLT-3 is then converted to an NRZI data stream.
4.3.4
Descrambling
The descrambler performs an inverse function to the scrambler in the transmitter and also performs the Serial In Parallel Out (SIPO) conversion of the data. During reception of IDLE (/I/) symbols. the descrambler synchronizes its descrambler key to the incoming stream. Once synchronization is achieved, the descrambler locks on this key and is able to descramble incoming data. Special logic in the descrambler ensures synchronization with the remote transceiver by searching for IDLE symbols within a window of 4000 bytes (40us). This window ensures that a maximum packet size of 1514 bytes, allowed by the IEEE 802.3 standard, can be received with no interference. If no IDLEsymbols are detected within this time-period, receive operation is aborted and the descrambler re-starts the synchronization process. The descrambler can be bypassed by setting bit 0 of register 31.
4.3.5
Alignment
The de-scrambled signal is then aligned into 5-bit code-groups by recognizing the /J/K/ Start-of-Stream Delimiter (SSD) pair at the start of a packet. Once the code-word alignment is determined, it is stored and utilized until the next start of frame.
4.3.6
5B/4B Decoding
The 5-bit code-groups are translated into 4-bit data nibbles according to the 4B/5B table. The translated data is presented on the RXD[3:0] signal lines. The SSD, /J/K/, is translated to "0101 0101" as the first 2 nibbles of the MAC preamble. Reception of the SSD causes the transceiver to assert the RXDV signal, indicating that valid data is available on the RXD bus. Successive valid code-groups are translated to data nibbles. Reception of either the End of Stream Delimiter (ESD) consisting of the /T/R/ symbols, or at least two /I/ symbols causes the transceiver to de-assert carrier sense and RXDV. These symbols are not translated into data. The decoding process may be bypassed by clearing bit 6 of register 31. When the decoding is bypassed the 5th receive data bit is driven out on RXER/RXD4/PHYAD0. Decoding may be bypassed only when the MAC interface is in MII mode.
4.3.7
Receive Data Valid Signal
The Receive Data Valid signal (RXDV) indicates that recovered and decoded nibbles are being presented on the RXD[3:0] outputs synchronous to RXCLK. RXDV becomes active after the /J/K/ delimiter has been recognized and RXD is aligned to nibble boundaries. It remains active until either the /T/R/ delimiter is recognized or link test indicates failure or SIGDET becomes false. RXDV is asserted when the first nibble of translated /J/K/ is ready for transfer over the Media Independent Interface (MII mode).
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CLEAR-TEXT RX_CLK RX_DV RXD
J
K
5
5
5
D
data
data
data
data
T
R
Idle
5
5
5
5
5
D
data
data
data
data
Figure 4.3 Relationship Between Received Data and Specific MII Signals
4.3.8
Receiver Errors
During a frame, unexpected code-groups are considered receive errors. Expected code groups are the DATA set (0 through F), and the /T/R/ (ESD) symbol pair. When a receive error occurs, the RXER signal is asserted and arbitrary data is driven onto the RXD[3:0] lines. Should an error be detected during the time that the /J/K/ delimiter is being decoded (bad SSD error), RXER is asserted true and the value `1110' is driven onto the RXD[3:0] lines. Note that the Valid Data signal is not yet asserted when the bad SSD error occurs.
4.3.9
100M Receive Data Across the MII/RMII Interface
In MII mode, the 4-bit data nibbles are sent to the MII block. These data nibbles are clocked to the controller at a rate of 25MHz. The controller samples the data on the rising edge of RXCLK. To ensure that the setup and hold requirements are met, the nibbles are clocked out of the transceiver on the falling edge of RXCLK. RXCLK is the 25MHz output clock for the MII bus. It is recovered from the received data to clock the RXD bus. If there is no received signal, it is derived from the system reference clock (XTAL1/CLKIN). When tracking the received data, RXCLK has a maximum jitter of 0.8ns (provided that the jitter of the input clock, XTAL1/CLKIN, is below 100ps). In RMII mode, the 2-bit data nibbles are sent to the RMII block. These data nibbles are clocked to the controller at a rate of 50MHz. The controller samples the data on the rising edge of XTAL1/CLKIN (REF_CLK). To ensure that the setup and hold requirements are met, the nibbles are clocked out of the transceiver on the falling edge of XTAL1/CLKIN (REF_CLK).
4.4
10Base-T Transmit
Data to be transmitted comes from the MAC layer controller. The 10Base-T transmitter receives 4-bit nibbles from the MII at a rate of 2.5MHz and converts them to a 10Mbps serial data stream. The data stream is then Manchester-encoded and sent to the analog transmitter, which drives a signal onto the twisted pair via the external magnetics. The 10M transmitter uses the following blocks: MII (digital) TX 10M (digital) 10M Transmitter (analog) 10M PLL (analog)
4.4.1
10M Transmit Data Across the MII/RMII Interface
The MAC controller drives the transmit data onto the TXD BUS. For MII, when the controller has driven TXEN high to indicate valid data, the data is latched by the MII block on the rising edge of TXCLK. The data is in the form of 4-bit wide 2.5MHz data.
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In order to comply with legacy 10Base-T MAC/Controllers, in Half-duplex mode the transceiver loops back the transmitted data, on the receive path. This does not confuse the MAC/Controller since the COL signal is not asserted during this time. The transceiver also supports the SQE (Heartbeat) signal. See Section 5.3.2, "Collision Detect," on page 50, for more details. For RMII, TXD[1:0] shall transition synchronously with respect to REF_CLK. When TXEN is asserted, TXD[1:0] are accepted for transmission by the LAN8720/LAN8720i. TXD[1:0] shall be "00" to indicate idle when TXEN is deasserted. Values of TXD[1:0] other than "00" when TXEN is deasserted are reserved for out-of-band signalling (to be defined). Values other than "00" on TXD[1:0] while TXEN is deasserted shall be ignored by the LAN8720/LAN8720i.TXD[1:0] shall provide valid data for each REF_CLK period while TXEN is asserted.
4.4.2
Manchester Encoding
The 4-bit wide data is sent to the TX10M block. The nibbles are converted to a 10Mbps serial NRZI data stream. The 10M PLL locks onto the external clock or internal oscillator and produces a 20MHz clock. This is used to Manchester encode the NRZ data stream. When no data is being transmitted (TXEN is low), the TX10M block outputs Normal Link Pulses (NLPs) to maintain communications with the remote link partner.
4.4.3
10M Transmit Drivers
The Manchester encoded data is sent to the analog transmitter where it is shaped and filtered before being driven out as a differential signal across the TXP and TXN outputs.
4.5
10Base-T Receive
The 10Base-T receiver gets the Manchester- encoded analog signal from the cable via the magnetics. It recovers the receive clock from the signal and uses this clock to recover the NRZI data stream. This 10M serial data is converted to 4-bit data nibbles which are passed to the controller across the MII at a rate of 2.5MHz. This 10M receiver uses the following blocks: Filter and SQUELCH (analog) 10M PLL (analog) RX 10M (digital) MII (digital)
4.5.1
10M Receive Input and Squelch
The Manchester signal from the cable is fed into the transceiver (on inputs RXP and RXN) via 1:1 ratio magnetics. It is first filtered to reduce any out-of-band noise. It then passes through a SQUELCH circuit. The SQUELCH is a set of amplitude and timing comparators that normally reject differential voltage levels below 300mV and detect and recognize differential voltages above 585mV.
4.5.2
Manchester Decoding
The output of the SQUELCH goes to the RX10M block where it is validated as Manchester encoded data. The polarity of the signal is also checked. If the polarity is reversed (local RXP is connected to RXN of the remote partner and vice versa), then this is identified and corrected. The reversed condition is indicated by the flag "XPOL", bit 4 in register 27. The 10M PLL is locked onto the received Manchester signal and from this, generates the received 20MHz clock. Using this clock, the Manchester encoded data is extracted and converted to a 10MHz NRZI data stream. It is then converted from serial to 4-bit wide parallel data. The RX10M block also detects valid 10Base-T IDLE signals - Normal Link Pulses (NLPs) - to maintain the link.
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4.5.3
10M Receive Data Across the MII/RMII Interface
For MII, the 4 bit data nibbles are sent to the MII block. In MII mode, these data nibbles are valid on the rising edge of the 2.5 MHz RXCLK. For RMII, the 2bit data nibbles are sent to the RMII block. In RMII mode, these data nibbles are valid on the rising edge of the RMII REF_CLK.
4.5.4
Jabber Detection
Jabber is a condition in which a station transmits for a period of time longer than the maximum permissible packet length, usually due to a fault condition, that results in holding the TXEN input for a long period. Special logic is used to detect the jabber state and abort the transmission to the line, within 45ms. Once TXEN is deasserted, the logic resets the jabber condition. As shown in Table 5.22, bit 1.1 indicates that a jabber condition was detected.
4.6
MAC Interface
The RMII block is responsible for the communication with the controller.
4.6.1
RMII
The SMSC LAN8720 supports the low pin count Reduced Media Independent Interface (RMII) intended for use between Ethernet transceivers and Switch ASICs. Under IEEE 802.3, an MII comprised of 16 pins for data and control is defined. In devices incorporating many MACs or transceiver interfaces such as switches, the number of pins can add significant cost as the port counts increase. The management interface (MDIO/MDC) is identical to MII. The RMII interface has the following characteristics: It is capable of supporting 10Mb/s and 100Mb/s data rates A single clock reference is used for both transmit and receive. It provides independent 2 bit wide (di-bit) transmit and receive data paths It uses LVCMOS signal levels, compatible with common digital CMOS ASIC processes The RMII includes 6 interface signals with one of the signals being optional: transmit data - TXD[1:0] transmit strobe - TXEN receive data - RXD[1:0] receive error - RXER (Optional) carrier sense - CRS_DV Reference Clock - (RMII references usually define this signal as REF_CLK)
4.6.1.1
CRS_DV - Carrier Sense/Receive Data Valid
The CRS_DV is asserted by the LAN8720/LAN8720i when the receive medium is non-idle. CRS_DV is asserted asynchronously on detection of carrier due to the criteria relevant to the operating mode. That is, in 10BASE-T mode, when squelch is passed or in 100BASE-X mode when 2 non-contiguous zeroes in 10 bits are detected, carrier is said to be detected. Loss of carrier shall result in the deassertion of CRS_DV synchronous to the cycle of REF_CLK which presents the first di-bit of a nibble onto RXD[1:0] (i.e. CRS_DV is deasserted only on nibble boundaries). If the LAN8720/LAN8720i has additional bits to be presented on RXD[1:0] following the initial deassertion of CRS_DV, then the LAN8720/LAN8720i shall assert CRS_DV on cycles of REF_CLK which present the second di-bit of each nibble and de-assert CRS_DV on cycles of REF_CLK which present the first di-bit of a nibble. The result is: Starting on nibble boundaries
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CRS_DV toggles at 25 MHz in 100Mb/s mode and 2.5 MHz in 10Mb/s mode when CRS ends before RXDV (i.e. the FIFO still has bits to transfer when the carrier event ends.) Therefore, the MAC can accurately recover RXDV and CRS. During a false carrier event, CRS_DV shall remain asserted for the duration of carrier activity. The data on RXD[1:0] is considered valid once CRS_DV is asserted. However, since the assertion of CRS_DV is asynchronous relative to REF_CLK, the data on RXD[1:0] shall be "00" until proper receive signal decoding takes place.
4.7
Reference Clock
The LAN8720 is designed to operate in one of two available modes as shown in Table 4.2. Table 4.2 REFCLK Modes MODE REF_CLK In Mode REF_CLK Out Mode REF_CLK DESCRIPTION Sourced externally, driven on the XTAL1/CLKIN pin Sourced by LAN8720/LAN8720i at the REFCLKO pin
During start-up, the LAN8720 monitors the LED2/nINTSEL pin to determine which mode has been configured as described in Section 4.10. In the first mode, the 50MHz REF_CLK is driven on the XTAL1/CLKIN pin. This is the traditional system configuration when using RMII, and is described in Section 4.7.1. In the second mode, an advanced feature of the LAN8720 allows a low-cost 25MHz crystal to be used as the reference for REF_CLK. This configuration may result in reduced system cost and is described in Section 4.7.2.
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4.7.1
REF_CLK In Mode
A 50MHz source of REF_CLK must be available external to the LAN8720 when using this mode. The clock is driven to both the MAC and PHY as shown in Figure 4.4.
MAC
Accepts external 50MHz clock
RMII
MDIO MDC nINT TXD[1:0] 2 TXEN RXD[1:0] 2 CRS_DV RXER
LAN8720 10/100 PHY 24-QFN RMII Mag
TXP TXN RXP RXN
RJ45
REF_CLK All RMII signals are synchronous to the supplied clock
XTAL1/CLKIN LED[2:1] 2 nRST Interface XTAL2
50MHz Reference Clock
Figure 4.4 External 50MHz clock sources the REF_CLK
4.7.2
REF_CLK OUT Mode
To reduce BOM cost, the LAN8720 includes a feature to generate the RMII REF_CLK signal from a low-cost, 25MHz, fundamental crystal. This type of crystal is inexpensive in comparison to 3rd overtone crystals that would normally be required for 50MHz. The MAC must be capable of operating with an external clock to take advantage of this feature as shown in Figure 4.5. The LAN8720 is a small size, low pin count device. In order to optimize package size and cost, the REFCLKO pin is multiplexed with the nINT pin. Therefore, in this specific mode of operation, the nINT pin is disabled since REFCLKO is used to provide the 50MHz clock to the MAC.
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nINT not available in this configuration
MAC
Capable of accepting 50MHz clock
RMII
MDIO MDC TXD[1:0] 2 TXEN RXD[1:0] 2 CRS_DV
LAN8720 10/100 PHY 24-QFN RMII Mag
TXP TXN
RJ45
REF_CLK
RXER
RXP RXN
REFCLKO
XTAL1/CLKIN LED[2:1]
25MHz
2 nRST Interface XTAL2
Figure 4.5 LAN8720 sources REF_CLK from a 25MHz crystal In some system architectures, a 25MHz clock source is available. The LAN8720 can be used to generate the REF_CLK to the MAC as shown in Figure 4.6. It is important to note that in this specific
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example, only a 25MHz clock can be used (clock cannot be 50MHz). Similar to the 25MHz crystal mode, the nINT function is disabled.
nINT not available in this configuration
MAC
Capable of accepting 50MHz clock
RMII
MDIO MDC TXD[1:0] 2 TXEN RXD[1:0]
LAN8720 10/100 PHY 24-QFN RMII Mag
TXP TXN RXP
RJ45
2 CRS_DV REF_CLK RXER
RXN
REFCLKO XTAL1/CLKIN LED[2:1] 2 nRST Interface XTAL2
25MHz Clock
Figure 4.6 LAN8720 Sources REF_CLK from External 25MHz Source The RMII REF_CLK is a continuous clock that provides the timing reference for CRS_DV, RXD[1:0], TXEN, TXD[1:0] and RXER. The LAN8720 uses REF_CLK as the network clock such that no buffering is required on the transmit data path. However, on the receive data path, the receiver recovers the clock from the incoming data stream, and the LAN8720 uses elasticity buffering to accommodate for differences between the recovered clock and the local REF_CLK.
4.8
Auto-negotiation
The purpose of the Auto-negotiation function is to automatically configure the transceiver to the optimum link parameters based on the capabilities of its link partner. Auto-negotiation is a mechanism for exchanging configuration information between two link-partners and automatically selecting the highest performance mode of operation supported by both sides. Auto-negotiation is fully defined in clause 28 of the IEEE 802.3 specification. Once auto-negotiation has completed, information about the resolved link can be passed back to the controller via the Serial Management Interface (SMI). The results of the negotiation process are reflected in the Speed Indication bits in register 31, as well as the Link Partner Ability Register (Register 5). The auto-negotiation protocol is a purely physical layer activity and proceeds independently of the MAC controller. The advertised capabilities of the transceiver are stored in register 4 of the SMI registers. The default advertised by the transceiver is determined by user-defined on-chip signal options. The following blocks are activated during an Auto-negotiation session: Auto-negotiation (digital)
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100M ADC (analog) 100M PLL (analog) 100M equalizer/BLW/clock recovery (DSP) 10M SQUELCH (analog) 10M PLL (analog) 10M Transmitter (analog)
When enabled, auto-negotiation is started by the occurrence of one of the following events: Hardware reset Software reset Power-down reset Link status down Setting register 0, bit 9 high (auto-negotiation restart) On detection of one of these events, the transceiver begins auto-negotiation by transmitting bursts of Fast Link Pulses (FLP). These are bursts of link pulses from the 10M transmitter. They are shaped as Normal Link Pulses and can pass uncorrupted down CAT-3 or CAT-5 cable. A Fast Link Pulse Burst consists of up to 33 pulses. The 17 odd-numbered pulses, which are always present, frame the FLP burst. The 16 even-numbered pulses, which may be present or absent, contain the data word being transmitted. Presence of a data pulse represents a "1", while absence represents a "0". The data transmitted by an FLP burst is known as a "Link Code Word." These are defined fully in IEEE 802.3 clause 28. In summary, the transceiver advertises 802.3 compliance in its selector field (the first 5 bits of the Link Code Word). It advertises its technology ability according to the bits set in register 4 of the SMI registers. There are 4 possible matches of the technology abilities. In the order of priority these are: 100M Full Duplex (Highest priority) 100M Half Duplex 10M Full Duplex 10M Half Duplex If the full capabilities of the transceiver are advertised (100M, Full Duplex), and if the link partner is capable of 10M and 100M, then auto-negotiation selects 100M as the highest performance mode. If the link partner is capable of Half and Full duplex modes, then auto-negotiation selects Full Duplex as the highest performance operation. Once a capability match has been determined, the link code words are repeated with the acknowledge bit set. Any difference in the main content of the link code words at this time will cause auto-negotiation to re-start. Auto-negotiation will also re-start if not all of the required FLP bursts are received. The capabilities advertised during auto-negotiation by the transceiver are initially determined by the logic levels latched on the MODE[2:0] bus after reset completes. This bus can also be used to disable auto-negotiation on power-up. Writing register 4 bits [8:5] allows software control of the capabilities advertised by the transceiver. Writing register 4 does not automatically re-start auto-negotiation. Register 0, bit 9 must be set before the new abilities will be advertised. Auto-negotiation can also be disabled via software by clearing register 0, bit 12. The LAN8720/LAN8720i does not support "Next Page" capability.
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4.8.1
Parallel Detection
If the LAN8720/LAN8720i is connected to a device lacking the ability to auto-negotiate (i.e. no FLPs are detected), it is able to determine the speed of the link based on either 100M MLT-3 symbols or 10M Normal Link Pulses. In this case the link is presumed to be Half Duplex per the IEEE standard. This ability is known as "Parallel Detection." This feature ensures interoperability with legacy link partners. If a link is formed via parallel detection, then bit 0 in register 6 is cleared to indicate that the Link Partner is not capable of auto-negotiation. The controller has access to this information via the management interface. If a fault occurs during parallel detection, bit 4 of register 6 is set. Register 5 is used to store the Link Partner Ability information, which is coded in the received FLPs. If the Link Partner is not auto-negotiation capable, then register 5 is updated after completion of parallel detection to reflect the speed capability of the Link Partner.
4.8.2
Re-starting Auto-negotiation
Auto-negotiation can be re-started at any time by setting register 0, bit 9. Auto-negotiation will also restart if the link is broken at any time. A broken link is caused by signal loss. This may occur because of a cable break, or because of an interruption in the signal transmitted by the Link Partner. Autonegotiation resumes in an attempt to determine the new link configuration. If the management entity re-starts Auto-negotiation by writing to bit 9 of the control register, the LAN8720/LAN8720i will respond by stopping all transmission/receiving operations. Once the break_link_timer is done, in the Auto-negotiation state-machine (approximately 1200ms) the autonegotiation will re-start. The Link Partner will have also dropped the link due to lack of a received signal, so it too will resume auto-negotiation.
4.8.3
Disabling Auto-negotiation
Auto-negotiation can be disabled by setting register 0, bit 12 to zero. The device will then force its speed of operation to reflect the information in register 0, bit 13 (speed) and register 0, bit 8 (duplex). The speed and duplex bits in register 0 should be ignored when auto-negotiation is enabled.
4.8.4
Half vs. Full Duplex
Half Duplex operation relies on the CSMA/CD (Carrier Sense Multiple Access / Collision Detect) protocol to handle network traffic and collisions. In this mode, the carrier sense signal, CRS, responds to both transmit and receive activity. In this mode, If data is received while the transceiver is transmitting, a collision results. In Full Duplex mode, the transceiver is able to transmit and receive data simultaneously. In this mode, CRS responds only to receive activity. The CSMA/CD protocol does not apply and collision detection is disabled.
4.9
HP Auto-MDIX Support
HP Auto-MDIX facilitates the use of CAT-3 (10 Base-T) or CAT-5 (100 Base-T) media UTP interconnect cable without consideration of interface wiring scheme. If a user plugs in either a direct connect LAN cable, or a cross-over patch cable, as shown in Figure 4.7, the SMSC LAN8720/LAN8720i Auto-MDIX transceiver is capable of configuring the TXP/TXN and RXP/RXN pins for correct transceiver operation. The internal logic of the device detects the TX and RX pins of the connecting device. Since the RX and TX line pairs are interchangeable, special PCB design considerations are needed to accommodate the symmetrical magnetics and termination of an Auto-MDIX design. The Auto-MDIX function can be disabled using the Special Control/Status Indications register (bit 27.15).
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Figure 4.7 Direct Cable Connection vs. Cross-over Cable Connection
4.10
nINTSEL Strapping and LED Polarity Selection
The LED2/nINTSEL pin is used to select between one of two available modes: REF_CLK In Mode and REF_CLK Out Mode. The configured mode determines the function of the nINT/REFCLK0 pin. Table 4.3 LED2/nINTSEL Configuration POLARITY MODE REF_CLK Out Mode REF_CLK In Mode REF_CLK DESCRIPTION nINT/REFCLK0 is the source of REF_CLK. nINT/REFCLK0 is an active low interrupt output.
LED2/nINTSEL = 0 LED2/nINTSEL = 1
When configured for REF_CLK Out Mode, the LAN8720 generates the 50MHz RMII REF_CLK and the interrupt is not available in this mode. The nINTSEL pin is shared with the LED2 pin. The LED2 output will automatically change polarity based on the presence of an external pull-down resistor. If the LED pin is pulled high (by the internal pull-up resistor) to select a logical high for nINTSEL, then the LED output will be active low. If the LED pin is pulled low by an external pull-down resistor to select a logical low nINTSEL, the LED output will then be an active high output. To set nINTSEL without LEDs, float the pin to set nINTSEL high or pull-down the pin with an external resistor to GND to set nINTSEL low. See Figure 4.8. The LED2/nINTSEL pin is latched on the rising edge of the nRST. The default setting is to float the pin high for nINT mode.
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nINTSEL = 1 LED output = active low
VDD2A
nINTSEL = 0 LED output = active high LED2/nINTSEL
10K
~270 ohms LED2/nINTSEL
~270 ohms
Figure 4.8 nINTSEL Strapping on LED2
4.11
REGOFF and LED Polarity Selection
The REGOFF configuration pin is shared with the LED1 pin. The LED1 output will automatically change polarity based on the presence of an external pull-up resistor. If the LED pin is pulled high to VDD2A by an external pull-up resistor to select a logical high for REGOFF, then the LED output will be active low. If the LED pin is pulled low by the internal pull-down resistor to select a logical low for REGOFF, the LED output will then be an active high output. To set REGOFF without LEDs, pull-up the pin with an external resistor to VDDIO to disable the regulator. See Figure 4.9.
REGOFF = 1 (Regulator OFF) LED output = active low
VDD2A
REGOFF = 0 LED output = active high LED1/REGOFF
10K ~270 ohms LED1/REGOFF
Figure 4.9 REGOFF Configuration on LED1
~270 ohms
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4.12
PHY Address Strapping
The PHY ADDRESS bit is latched into an internal register at the end of a hardware reset. The address bit is input on the RXER/PHYAD0 pin. The default setting is PHYAD0=0 as described in Section 5.3.9.1.
4.13
Variable Voltage I/O
The Digital I/O pins on the LAN8720/LAN8720i are variable voltage to take advantage of low power savings from shrinking technologies. These pins can operate from a low I/O voltage of +1.8V-10% up to +3.3V+10%. The I/O voltage the System Designer applies on VDDIO needs to maintain its value with a tolerance of 10%. Varying the voltage up or down, after the transceiver has completed poweron reset can cause errors in the transceiver operation.
4.14
Transceiver Management Control
The Management Control module includes 3 blocks: Serial Management Interface (SMI) Management Registers Set Interrupt
4.14.1
Serial Management Interface (SMI)
The Serial Management Interface is used to control the LAN8720/LAN8720i and obtain its status. This interface supports registers 0 through 6 as required by Clause 22 of the 802.3 standard, as well as "vendor-specific" registers 16 to 31 allowed by the specification. Non-supported registers (7 to 15) will be read as hexadecimal "FFFF". At the system level there are 2 signals, MDIO and MDC where MDIO is bi-directional open-drain and MDC is the clock. A special feature (enabled by register 17 bit 3) forces the transceiver to disregard the PHY-Address in the SMI packet causing the transceiver to respond to any address. This feature is useful in multi-PHY applications and in production testing, where the same register can be written in all the transceivers using a single write transaction. The MDC signal is an aperiodic clock provided by the station management controller (SMC). The MDIO signal receives serial data (commands) from the controller SMC, and sends serial data (status) to the SMC. The minimum time between edges of the MDC is 160 ns. There is no maximum time between edges. The minimum cycle time (time between two consecutive rising or two consecutive falling edges) is 400 ns. These modest timing requirements allow this interface to be easily driven by the I/O port of a microcontroller. The data on the MDIO line is latched on the rising edge of the MDC. The frame structure and timing of the data is shown in Figure 4.10 and Figure 4.11. The timing relationships of the MDIO signals are further described in Section 6.1, "Serial Management Interface (SMI) Timing," on page 55.
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Read Cycle
MDC MDI0
32 1's Preamble 0 1 1 0 A4 A3 A2 A1 A0 R4 R3 R2 R1 R0 PHY Address Register Address Turn Around
D15 D14
... ...
Data
D1
D0
Start of Frame
OP Code
Data To Phy
Data From Phy
Figure 4.10 MDIO Timing and Frame Structure - READ Cycle
Write Cycle
MDC MDIO
32 1's Preamble 0 1 0 1 A4 A3 A2 A1 A0 R4 R3 R2 R1 R0 PHY Address Register Address Turn Around
D15 D14
... ...
Data
D1
D0
Start of Frame
OP Code
Data To Phy
Figure 4.11 MDIO Timing and Frame Structure - WRITE Cycle
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Chapter 5 SMI Register Mapping
Table 5.1 Control Register: Register 0 (Basic) 15 Reset 14 Loopback 13 Speed Select 12 A/N Enable 11 Power Down 10 Isolate 9 Restart A/N 8 Duplex Mode 7 Collision Test 6 5 4 3 Reserved 2 1 0
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Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Table 5.2 Status Register: Register 1 (Basic) 15 100Base -T4 14 100Base -TX Full Duplex 13 100Base -TX Half Duplex 12 10BaseT Full Duplex 11 10BaseT Half Duplex 10 9 8 Reserved 7 6 5 A/N Complete 4 Remote Fault 3 A/N Ability 2 Link Status 1 Jabber Detect 0 Extended Capability
Table 5.3 PHY ID 1 Register: Register 2 (Extended) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PHY ID Number (Bits 3-18 of the Organizationally Unique Identifier - OUI)
Table 5.4 PHY ID 2 Register: Register 3 (Extended) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PHY ID Number (Bits 19-24 of the Organizationally Unique Identifier - OUI)
Manufacturer Model Number
Manufacturer Revision Number
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Table 5.5 Auto-Negotiation Advertisement: Register 4 (Extended) 15 Next Page 14 Reserved 13 Remote Fault 12 Reserved 11 Pause Operation 10 9 100BaseT4 8 100BaseTX Full Duplex 7 100BaseTX 6 10BaseT Full Duplex 5 10BaseT 4 3 2 1 0
IEEE 802.3 Selector Field
Table 5.6 Auto-Negotiation Link Partner Base Page Ability Register: Register 5 (Extended) 15 Next Page 14 Acknowledge 13 Remote Fault 12 11 10 Pause 9 100BaseT4 8 100Base-TX Full Duplex 7 100BaseTX 6 10Base-T Full Duplex 5 10BaseT 4 3 2 1 0
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Reserved
IEEE 802.3 Selector Field
Table 5.7 Auto-Negotiation Expansion Register: Register 6 (Extended) 15 14 13 12 11 10 Reserved 9 8 7 6 5 4 Parallel Detect Fault 3 Link Partner Next Page Able 2 Next Page Able 1 Page Received 0 Link Partner A/N Able
Table 5.8 Register 15 (Extended) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
IEEE Reserved
Table 5.9 Silicon Revision Register 16: Vendor-Specific 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
Silicon Revision
Reserved
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Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Table 5.10 Mode Control/ Status Register 17: Vendor-Specific 1 5 14 13 EDPWRDOWN 12 RSVD 11 LOWSQEN 10 MDPREBP 9 FARLOOPBACK 8 7 6 ALTINT 5 4 3 PHYADBP 2 Force Good Link Status 1 ENERGYON 0 RSVD
RSVD
RSVD
RSVD
RSVD = Reserved Table 5.11 Special Modes Register 18: Vendor-Specific 15 Reserved 14 MIIMODE 13 12 11 Reserved 10 9 8 7 6 MODE 5 4 3 2 PHYAD 1 0
Table 5.12 Register 24: Vendor-Specific 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
Table 5.13 Register 25: Vendor-Specific 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
Table 5.14 Symbol Error Counter Register 26: Vendor-Specific 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Symbol Error Counter
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Table 5.15 Special Control/Status Indications Register 27: Vendor-Specific 15 AMDIXCTRL 14 Reserved 13 CH_SELECT 12 Reserved 11 SQEOFF 10 9 8 7 6 5 4 XPOL 3 2 1 0
Reserved
Reserved
Table 5.16 Special Internal Testability Control Register 28: Vendor-Specific 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
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Table 5.17 Interrupt Source Flags Register 29: Vendor-Specific 15 14 13 12 Reserved 11 10 9 8 7 INT7 6 INT6 5 INT5 4 INT4 3 INT3 2 INT2 1 INT1 0 Reserved
Table 5.18 Interrupt Mask Register 30: Vendor-Specific 15 14 13 12 11 10 9 8 7 6 5 4 Mask Bits 3 2 1 0 Reserved
Reserved
Table 5.19 PHY Special Control/Status Register 31: Vendor-Specific 15 14 Reserved 13 12 Autodone 11 10 9 GPO2 8 GPO1 7 GPO0 6 Enable 4B5B 5 Reserved 4 3 Speed Indication 2 1 Reserved 0 Scramble Disable
Reserved
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
The following registers are supported (register numbers are in decimal): Table 5.20 SMI Register Mapping REGISTER # 0 1 2 3 4 5 6 16 17 18 20 21 22 23 26 27 28 29 30 31 DESCRIPTION Basic Control Register Basic Status Register PHY Identifier 1 PHY Identifier 2 Auto-Negotiation Advertisement Register Auto-Negotiation Link Partner Ability Register Auto-Negotiation Expansion Register Silicon Revision Register Mode Control/Status Register Special Modes Reserved Reserved Reserved Reserved Symbol Error Counter Register Control / Status Indication Register Special internal testability controls Interrupt Source Register Interrupt Mask Register PHY Special Control/Status Register Group Basic Basic Extended Extended Extended Extended Extended Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific Vendor-specific
5.1
SMI Register Format
The mode key is as follows: RW = Read/write, SC = Self clearing, WO = Write only, RO = Read only, LH = Latch high, clear on read of register, LL = Latch low, clear on read of register, NASR = Not Affected by Software Reset X = Either a 1 or 0.
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Table 5.21 Register 0 - Basic Control ADDRESS 0.15 NAME Reset DESCRIPTION 1 = software reset. Bit is self-clearing. For best results, when setting this bit do not set other bits in this register. The configuration (as described in Section 5.3.9.2) is set from the register bit values, and not from the mode pins. 1 = loopback mode, 0 = normal operation 1 = 100Mbps, 0 = 10Mbps. Ignored if Auto Negotiation is enabled (0.12 = 1). 1 = enable auto-negotiate process (overrides 0.13 and 0.8) 0 = disable auto-negotiate process 1 = General power down mode, 0 = normal operation 1 = electrical isolation of transceiver from MII 0 = normal operation 1 = restart auto-negotiate process 0 = normal operation. Bit is self-clearing. 1 = Full duplex, 0 = Half duplex. Ignored if Auto Negotiation is enabled (0.12 = 1). 1 = enable COL test, 0 = disable COL test MODE RW/ SC DEFAULT 0
0.14 0.13
Loopback Speed Select
RW RW
0 Set by MODE[2:0] bus Set by MODE[2:0] bus 0 0 0 Set by MODE[2:0] bus 0 0
0.12
AutoNegotiation Enable Power Down Isolate Restart AutoNegotiate Duplex Mode
RW
0.11 0.10 0.9 0.8
RW RW RW/ SC RW
0.7 0.6:0
Collision Test Reserved
RW RO
Table 5.22 Register 1 - Basic Status ADDRESS 1.15 1.14 1.13 1.12 1.11 1.10:6 1.5 NAME 100Base-T4 100Base-TX Full Duplex 100Base-TX Half Duplex 10Base-T Full Duplex 10Base-T Half Duplex Reserved Auto-Negotiate Complete 1 = auto-negotiate process completed 0 = auto-negotiate process not completed RO 0 1 = T4 able, 0 = no T4 ability 1 = TX with full duplex, 0 = no TX full duplex ability 1 = TX with half duplex, 0 = no TX half duplex ability 1 = 10Mbps with full duplex 0 = no 10Mbps with full duplex ability 1 = 10Mbps with half duplex 0 = no 10Mbps with half duplex ability DESCRIPTION MODE RO RO RO RO RO DEFAULT 0 1 1 1 1
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Table 5.22 Register 1 - Basic Status (continued) ADDRESS 1.4 1.3 1.2 1.1 1.0 NAME Remote Fault Auto-Negotiate Ability Link Status Jabber Detect Extended Capabilities DESCRIPTION 1 = remote fault condition detected 0 = no remote fault 1 = able to perform auto-negotiation function 0 = unable to perform auto-negotiation function 1 = link is up, 0 = link is down 1 = jabber condition detected 0 = no jabber condition detected 1 = supports extended capabilities registers 0 = does not support extended capabilities registers MODE RO/ LH RO RO/ LL RO/ LH RO DEFAULT 0 1 X X 1
Table 5.23 Register 2 - PHY Identifier 1 ADDRESS 2.15:0 NAME PHY ID Number DESCRIPTION Assigned to the 3rd through 18th bits of the Organizationally Unique Identifier (OUI), respectively. OUI=00800Fh MODE RW DEFAULT 0007h
Table 5.24 Register 3 - PHY Identifier 2 ADDRESS 3.15:10 3.9:4 3.3:0 NAME PHY ID Number Model Number Revision Number DESCRIPTION Assigned to the 19th through 24th bits of the OUI. Six-bit manufacturer's model number. Four-bit manufacturer's revision number. MODE RW RW RW DEFAULT 30h 0Fh DEVICE REV
Table 5.25 Register 4 - Auto Negotiation Advertisement ADDRESS 4.15 NAME Next Page DESCRIPTION 1 = next page capable, 0 = no next page ability This Phy does not support next page ability. MODE RO DEFAULT 0
4.14 4.13 4.12 4.11:10
Reserved Remote Fault Reserved Pause Operation 00 = No PAUSE 01= Symmetric PAUSE 10= Asymmetric PAUSE toward link partner 11 = Both Symmetric PAUSE and Asymmetric PAUSE toward local device 1 = remote fault detected, 0 = no remote fault
RO RW
0 0
R/W
00
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Table 5.25 Register 4 - Auto Negotiation Advertisement (continued) ADDRESS 4.9 NAME 100Base-T4 DESCRIPTION 1 = T4 able, 0 = no T4 ability This Phy does not support 100Base-T4. 1 = TX with full duplex, 0 = no TX full duplex ability 1 = TX able, 0 = no TX ability 1 = 10Mbps with full duplex 0 = no 10Mbps with full duplex ability 1 = 10Mbps able, 0 = no 10Mbps ability [00001] = IEEE 802.3 MODE RO DEFAULT 0
4.8
100Base-TX Full Duplex 100Base-TX 10Base-T Full Duplex 10Base-T
RW
Set by MODE[2:0] bus 1 Set by MODE[2:0] bus Set by MODE[2:0] bus 00001
4.7 4.6
RW RW
4.5
RW
4.4:0
Selector Field
RW
Table 5.26 Register 5 - Auto Negotiation Link Partner Ability ADDRESS 5.15 NAME Next Page DESCRIPTION 1 = "Next Page" capable, 0 = no "Next Page" ability This Phy does not support next page ability. 1 = link code word received from partner 0 = link code word not yet received 1 = remote fault detected, 0 = no remote fault MODE RO DEFAULT 0
5.14 5.13 5.12:11 5.10 5.9
Acknowledge Remote Fault Reserved Pause Operation 100Base-T4
RO RO RO
0 0 0 0 0
1 = Pause Operation is supported by remote MAC, 0 = Pause Operation is not supported by remote MAC 1 = T4 able, 0 = no T4 ability. This Phy does not support T4 ability. 1 = TX with full duplex, 0 = no TX full duplex ability 1 = TX able, 0 = no TX ability 1 = 10Mbps with full duplex 0 = no 10Mbps with full duplex ability 1 = 10Mbps able, 0 = no 10Mbps ability [00001] = IEEE 802.3
RO RO
5.8 5.7 5.6 5.5 5.4:0
100Base-TX Full Duplex 100Base-TX 10Base-T Full Duplex 10Base-T Selector Field
RO RO RO RO RO
0 0 0 0 00001
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Table 5.27 Register 6 - Auto Negotiation Expansion ADDRESS 6.15:5 6.4 6.3 6.2 6.1 6.0 NAME Reserved Parallel Detection Fault Link Partner Next Page Able Next Page Able Page Received Link Partner AutoNegotiation Able 1 = fault detected by parallel detection logic 0 = no fault detected by parallel detection logic 1 = link partner has next page ability 0 = link partner does not have next page ability 1 = local device has next page ability 0 = local device does not have next page ability 1 = new page received 0 = new page not yet received 1 = link partner has auto-negotiation ability 0 = link partner does not have auto-negotiation ability DESCRIPTION MODE RO RO/ LH RO RO RO/ LH RO DEFAULT 0 0 0 0 0 0
Table 5.28 Register 16 - Silicon Revision ADDRESS 16.15:10 16.9:6 16.5:0 NAME Reserved Silicon Revision Reserved Four-bit silicon revision identifier. DESCRIPTION MODE RO RO RO DEFAULT 0 0001 0
Table 5.29 Register 17 - Mode Control/Status ADDRESS 17.15:14 17.13 NAME Reserved EDPWRDOWN DESCRIPTION Write as 0; ignore on read. Enable the Energy Detect Power-Down mode: 0 = Energy Detect Power-Down is disabled 1 = Energy Detect Power-Down is enabled Write as 0, ignore on read The Low_Squelch signal is equal to LOWSQEN AND EDPWRDOWN. Low_Squelch = 1 implies a lower threshold (more sensitive). Low_Squelch = 0 implies a higher threshold (less sensitive). Management Data Preamble Bypass: 0 - detect SMI packets with Preamble 1 - detect SMI packets without preamble Force the module to the FAR Loop Back mode, i.e. all the received packets are sent back simultaneously (in 100Base-TX only). This bit is only active in RMII mode, as described in Section 5.3.8.2. This mode works even if MII Isolate (0.10) is set. Write as 0, ignore on read.
44
MODE RW RW
DEFAULT 0 0
17.12 17.11
Reserved LOWSQEN
RW RW
0 0
17.10
MDPREBP
RW
0
17.9
FARLOOPBACK
RW
0
17.8:7
Reserved
RW
00
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Table 5.29 Register 17 - Mode Control/Status (continued) ADDRESS 17.6 NAME ALTINT DESCRIPTION Alternate Interrupt Mode. 0 = Primary interrupt system enabled (Default). 1 = Alternate interrupt system enabled. See Section 5.2, "Interrupt Management," on page 48. Write as 0, ignore on read. 1 = PHY disregards PHY address in SMI access write. 0 = normal operation; 1 = force 100TX- link active; Note: 17.1 ENERGYON This bit should be set only during lab testing RO X MODE RW DEFAULT 0
17.5:4 17.3 17.2
Reserved PHYADBP Force Good Link Status
RW RW RW
00 0 0
ENERGYON - indicates whether energy is detected on the line (see Section 5.3.5.2, "Energy Detect Power-Down," on page 51); it goes to "0" if no valid energy is detected within 256ms. Reset to "1" by hardware reset, unaffected by SW reset. Write as 0. Ignore on read.
17.0
Reserved
RW
0
Table 5.30 Register 18 - Special Modes ADDRESS 18.15 18.14 18.13:8 18.7:5 NAME Reserved Reserved Reserved MODE DESCRIPTION Write as 0, ignore on read. Write as 1, ignore on read. Write as 0, ignore on read. Transceiver Mode of operation. Refer to Section 5.3.9.2, "Mode Bus - MODE[2:0]," on page 53 for more details. PHY Address. The PHY Address is used for the SMI address and for the initialization of the Cipher (Scrambler) key. Refer to Section 5.3.9.1, "Physical Address Bus PHYAD[0]," on page 53 for more details. Table 5.31 Register 26 - Symbol Error Counter ADDRESS 26.15:0 NAME Sym_Err_Cnt DESCRIPTION 100Base-TX receiver-based error register that increments when an invalid code symbol is received including IDLE symbols. The counter is incremented only once per packet, even when the received packet contains more than one symbol error. The 16-bit register counts up to 65,536 (216) and rolls over to 0 if incremented beyond that value. This register is cleared on reset, but is not cleared by reading the register. It does not increment in 10Base-T mode. MODE RO DEFAULT 0 MODE RW RW, NASR RW, NASR RW, NASR RW, NASR DEFAULT 0 1 000000 XXX
18.4:0
PHYAD
PHYAD
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Table 5.32 Register 27 - Special Control/Status Indications ADDRESS 27.15 NAME AMDIXCTRL DESCRIPTION HP Auto-MDIX control 0 - Auto-MDIX enable 1 - Auto-MDIX disabled (use 27.13 to control channel) Reserved Manual Channel Select 0 - MDI -TX transmits RX receives 1 - MDIX -TX receives RX transmits Write as 0. Ignore on read. Disable the SQE (Signal Quality Error) test (Heartbeat): 0 - SQE test is enabled. 1 - SQE test is disabled. Write as 0. Ignore on read. Polarity state of the 10Base-T: 0 - Normal polarity 1 - Reversed polarity Reserved MODE RW DEFAULT 0
27.14 27.13
Reserved CH_SELECT
RW RW
0 0
27.12 27:11
Reserved SQEOFF
RW RW, NASR
0 0
27.10:5 27.4
Reserved XPOL
RW RO
000000 0
27.3:0
Reserved
RO
XXXXb
Table 5.33 Register 28 - Special Internal Testability Controls ADDRESS 28.15:0 NAME Reserved DESCRIPTION Do not write to this register. Ignore on read. MODE RW DEFAULT N/A
Table 5.34 Register 29 - Interrupt Source Flags ADDRESS 29.15:8 29.7 29.6 29.5 29.4 29.3 29.2 NAME Reserved INT7 INT6 INT5 INT4 INT3 INT2 Ignore on read. 1 = ENERGYON generated 0 = not source of interrupt 1 = Auto-Negotiation complete 0 = not source of interrupt 1 = Remote Fault Detected 0 = not source of interrupt 1 = Link Down (link status negated) 0 = not source of interrupt 1 = Auto-Negotiation LP Acknowledge 0 = not source of interrupt 1 = Parallel Detection Fault 0 = not source of interrupt DESCRIPTION MODE RO/ LH RO/ LH RO/ LH RO/ LH RO/ LH RO/ LH RO/ LH DEFAULT 0 X X X X X X
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Table 5.34 Register 29 - Interrupt Source Flags (continued) ADDRESS 29.1 29.0 NAME INT1 Reserved DESCRIPTION 1 = Auto-Negotiation Page Received 0 = not source of interrupt Ignore on read. MODE RO/ LH RO/ LH DEFAULT X 0
Table 5.35 Register 30 - Interrupt Mask ADDRESS 30.15:8 30.7:1 30.0 NAME Reserved Mask Bits Reserved DESCRIPTION Write as 0; ignore on read. 1 = interrupt source is enabled 0 = interrupt source is masked Write as 0; ignore on read MODE RO RW RO DEFAULT 0 0 0
Table 5.36 Register 31 - PHY Special Control/Status ADDRESS 31.15:13 31.12 NAME Reserved Autodone DESCRIPTION Write as 0, ignore on read. Auto-negotiation done indication: 0 = Auto-negotiation is not done or disabled (or not active) 1 = Auto-negotiation is done Note: 31.11:10 31.9:7 31.6 Reserved GPO[2:0] Enable 4B5B This is a duplicate of register 1.5, however reads to register 31 do not clear status bits. RW RW RW XX 0 1 MODE RW RO DEFAULT 0 0
Write as 0, ignore on Read. General Purpose Output connected to signals GPO[2:0] 0 = Bypass encoder/decoder. 1 = enable 4B5B encoding/decoding. MAC Interface must be configured in MII mode. Write as 0, ignore on Read. HCDSPEED value: [001]=10Mbps Half-duplex [101]=10Mbps Full-duplex [010]=100Base-TX Half-duplex [110]=100Base-TX Full-duplex Write as 0; ignore on Read 0 = enable data scrambling 1 = disable data scrambling,
31.5 31.4:2
Reserved Speed Indication
RW RO
0 XXX
31.1 31.0
Reserved Scramble Disable
RW RW
0 0
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5.2
Interrupt Management
The Management interface supports an interrupt capability that is not a part of the IEEE 802.3 specification. It generates an active low asynchronous interrupt signal on the nINT output whenever certain events are detected as setup by the Interrupt Mask Register 30. The Interrupt system on the SMSC The LAN8720 has two modes, a Primary Interrupt mode and an Alternative Interrupt mode. Both systems will assert the nINT pin low when the corresponding mask bit is set, the difference is how they de-assert the output interrupt signal nINT. The Primary interrupt mode is the default interrupt mode after a power-up or hard reset, the Alternative interrupt mode would need to be setup again after a power-up or hard reset.
5.2.1
Primary Interrupt System
The Primary Interrupt system is the default interrupt mode, (Bit 17.6 = `0'). The Primary Interrupt System is always selected after power-up or hard reset. To set an interrupt, set the corresponding mask bit in the interrupt Mask register 30 (see Table 5.37). Then when the event to assert nINT is true, the nINT output will be asserted. When the corresponding Event to De-Assert nINT is true, then the nINT will be de-asserted. Table 5.37 Interrupt Management Table INTERRUPT SOURCE FLAG 29.7 29.6 29.5 ENERGYON Auto-Negotiation complete Remote Fault Detected Link Down Auto-Negotiation LP Acknowledge Parallel Detection Fault EVENT TO ASSERT nINT Rising 17.1 (Note 5.1) Rising 1.5 Rising 1.4 EVENT TO DE-ASSERT nINT Falling 17.1 or Reading register 29 Falling 1.5 or Reading register 29 Falling 1.4, or Reading register 1 or Reading register 29 Reading register 1 or Reading register 29 Falling 5.14 or Read register 29 Falling 6.4 or Reading register 6, or Reading register 29 or Re-Auto Negotiate or Link down Falling of 6.1 or Reading register 6, or Reading register 29 Re-Auto Negotiate, or Link Down.
MASK 30.7 30.6 30.5
INTERRUPT SOURCE 17.1 1.5 1.4 ENERGYON Auto-Negotiate Complete Remote Fault
30.4 30.3 30.2
29.4 29.3 29.2
1.2 5.14 6.4
Link Status Acknowledge Parallel Detection Fault
Falling 1.2 Rising 5.14 Rising 6.4
30.1
29.1
Auto-Negotiation Page Received
6.1
Page Received
Rising 6.1
Note 5.1
If the mask bit is enabled and nINT has been de-asserted while ENERGYON is still high, nINT will assert for 256 ms, approximately one second after ENERGYON goes low when the Cable is unplugged. To prevent an unexpected assertion of nINT, the ENERGYON interrupt mask should always be cleared as part of the ENERGYON interrupt service routine.
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Note: The ENERGYON bit 17.1 is defaulted to a `1' at the start of the signal acquisition process, therefore the Interrupt source flag 29.7 will also read as a `1' at power-up. If no signal is present, then both 17.1 and 29.7 will clear within a few milliseconds.
5.2.2
Alternate Interrupt System
The Alternative method is enabled by writing a `1' to 17.6 (ALTINT). To set an interrupt, set the corresponding bit of the in the Mask Register 30, (see Table 5.38). To Clear an interrupt, either clear the corresponding bit in the Mask Register (30), this will de-assert the nINT output, or Clear the Interrupt Source, and write a `1' to the corresponding Interrupt Source Flag. Writing a `1' to the Interrupt Source Flag will cause the state machine to check the Interrupt Source to determine if the Interrupt Source Flag should clear or stay as a `1'. If the Condition to DeAssert is true, then the Interrupt Source Flag is cleared, and the nINT is also de-asserted. If the Condition to De-Assert is false, then the Interrupt Source Flag remains set, and the nINT remains asserted. For example 30.7 is set to `1' to enable the ENERGYON interrupt. After a cable is plugged in, ENERGYON (17.1) goes active and nINT will be asserted low. To de-assert the nINT interrupt output, either. 1. Clear the ENERGYON bit (17.1), by removing the cable, then writing a `1' to register 29.7. Or 2. Clear the Mask bit 30.1 by writing a `0' to 30.1. Table 5.38 Alternative Interrupt System Management Table CONDITION TO DE-ASSERT 17.1 low 1.5 low 1.4 low 1.2 high 5.14 low 6.4 low 6.1 low BIT TO CLEAR nINT 29.7 29.6 29.5 29.4 29.3 29.2 29.1
MASK 30.7 30.6 30.5 30.4 30.3 30.2 30.1
INTERRUPT SOURCE FLAG 29.7 29.6 29.5 29.4 29.3 29.2 29.1 ENERGYON Auto-Negotiation complete Remote Fault Detected Link Down Auto-Negotiation LP Acknowledge Parallel Detection Fault Auto-Negotiation Page Received
INTERRUPT SOURCE 17.1 1.5 1.4 1.2 5.14 6.4 6.1 ENERGYON Auto-Negotiate Complete Remote Fault Link Status Acknowledge Parallel Detection Fault Page Received
EVENT TO ASSERT nINT Rising 17.1 Rising 1.5 Rising 1.4 Falling 1.2 Rising 5.14 Rising 6.4 Rising 6.1
Note: The ENERGYON bit 17.1 is defaulted to a `1' at the start of the signal acquisition process, therefore the Interrupt source flag 29.7 will also read as a `1' at power-up. If no signal is present, then both 17.1 and 29.7 will clear within a few milliseconds.
5.3
5.3.1
Miscellaneous Functions
Carrier Sense
The carrier sense is output on CRS. CRS is a signal defined by the MII specification in the IEEE 802.3u standard. The LAN8720 asserts CRS based only on receive activity whenever the transceiver is either
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in repeater mode or full-duplex mode. Otherwise the transceiver asserts CRS based on either transmit or receive activity. The carrier sense logic uses the encoded, unscrambled data to determine carrier activity status. It activates carrier sense with the detection of 2 non-contiguous zeros within any 10 bit span. Carrier sense terminates if a span of 10 consecutive ones is detected before a /J/K/ Start-of Stream Delimiter pair. If an SSD pair is detected, carrier sense is asserted until either /T/R/ End-of-Stream Delimiter pair or a pair of IDLE symbols is detected. Carrier is negated after the /T/ symbol or the first IDLE. If /T/ is not followed by /R/, then carrier is maintained. Carrier is treated similarly for IDLE followed by some non-IDLE symbol.
5.3.2
Collision Detect
A collision is the occurrence of simultaneous transmit and receive operations. The COL output is asserted to indicate that a collision has been detected. COL remains active for the duration of the collision. COL is changed asynchronously to both RXCLK and TXCLK. The COL output becomes inactive during full duplex mode. COL may be tested by setting register 0, bit 7 high. This enables the collision test. COL will be asserted within 512 bit times of TXEN rising and will be de-asserted within 4 bit times of TXEN falling. In 10M mode, COL pulses for approximately 10 bit times (1us), 2us after each transmitted packet (deassertion of TXEN). This is the Signal Quality Error (SQE) signal and indicates that the transmission was successful. The user can disable this pulse by setting bit 11 in register 27.
5.3.3
Isolate Mode
The LAN8720 data paths may be electrically isolated from the MII by setting register 0, bit 10 to a logic one. In isolation mode, the transceiver does not respond to the TXD, TXEN and TXER inputs, but does respond to management transactions. Isolation provides a means for multiple transceivers to be connected to the same MII without contention occurring. The transceiver is not isolated on power-up (bit 0:10 = 0).
5.3.4
Link Integrity Test
The LAN8720 performs the link integrity test as outlined in the IEEE 802.3u (Clause 24-15) Link Monitor state diagram. The link status is multiplexed with the 10Mbps link status to form the reportable link status bit in Serial Management Register 1, and is driven to the LINK LED. The DSP indicates a valid MLT-3 waveform present on the RXP and RXN signals as defined by the ANSI X3.263 TP-PMD standard, to the Link Monitor state-machine, using internal signal called DATA_VALID. When DATA_VALID is asserted the control logic moves into a Link-Ready state, and waits for an enable from the Auto Negotiation block. When received, the Link-Up state is entered, and the Transmit and Receive logic blocks become active. Should Auto Negotiation be disabled, the link integrity logic moves immediately to the Link-Up state, when the DATA_VALID is asserted. Note that to allow the line to stabilize, the link integrity logic will wait a minimum of 330 sec from the time DATA_VALID is asserted until the Link-Ready state is entered. Should the DATA_VALID input be negated at any time, this logic will immediately negate the Link signal and enter the Link-Down state. When the 10/100 digital block is in 10Base-T mode, the link status is from the 10Base-T receiver logic.
5.3.5
Power-Down modes
There are 2 power-down modes for the LAN8720 described in the following sections.
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5.3.5.1
General Power-Down
This power-down is controlled by register 0, bit 11. In this mode the entire transceiver, except the management interface, is powered-down and stays in that condition as long as bit 0.11 is HIGH. When bit 0.11 is cleared, the transceiver powers up and is automatically reset.
5.3.5.2
Energy Detect Power-Down
This power-down mode is activated by setting bit 17.13 to 1. In this mode when no energy is present on the line the transceiver is powered down, except for the management interface, the SQUELCH circuit and the ENERGYON logic. The ENERGYON logic is used to detect the presence of valid energy from 100Base-TX, 10Base-T, or Auto-negotiation signals In this mode, when the ENERGYON signal is low, the transceiver is powered-down, and nothing is transmitted. When energy is received - link pulses or packets - the ENERGYON signal goes high, and the transceiver powers-up. It automatically resets itself into the state it had prior to power-down, and asserts the nINT interrupt if the ENERGYON interrupt is enabled. The first and possibly the second packet to activate ENERGYON may be lost. When 17.13 is low, energy detect power-down is disabled.
5.3.6
Reset
The LAN8720 registers are reset by the Hardware and Software resets. Some SMI register bits are not cleared by Software reset, and these are marked "NASR" in the register tables. The SMI registers are not reset by the power-down modes described in Section 5.3.5. For the first 16us after coming out of reset, the MII will run at 2.5 MHz. After that it will switch to 25 MHz if auto-negotiation is enabled.
5.3.6.1
Hardware Reset
Hardware reset is asserted by driving the nRST input low. When the nRST input is driven by an external source, it should be held LOW for at least 100 us to ensure that the transceiver is properly reset. During a hardware reset an external clock must be supplied to the XTAL1/CLKIN signal.
5.3.6.2
Software Reset
Software reset is activated by writing register 0, bit 15 high. This signal is self- clearing. The SMI registers are reset except those that are marked "NASR" in the register tables. The IEEE 802.3u standard, clause 22 (22.2.4.1.1) states that the reset process should be completed within 0.5s from the setting of this bit.
5.3.7
LED Description
The LAN8720 provides two LED signals. These provide a convenient means to determine the mode of operation of the transceiver. All LED signals are either active high or active low as described in Section 4.10 and Section 4.11. The LED1 output is driven active whenever the LAN8720 detects a valid link, and blinks when CRS is active (high) indicating activity. The LED2 output is driven active when the operating speed is 100Mbit/s. This LED will go inactive when the operating speed is 10Mbit/s or during line isolation (register 31 bit 5).
5.3.8
Loopback Operation
The LAN8720 may be configured for near-end loopback and far loopback.
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5.3.8.1
Near-end Loopback
Near-end loopback is a mode that sends the digital transmit data back out the receive data signals for testing purposes as indicated by the blue arrows in Figure 5.1.The near-end loopback mode is enabled by setting bit register 0 bit 14 to logic one. A large percentage of the digital circuitry is operational near-end loopback mode, because data is routed through the PCS and PMA layers into the PMD sublayer before it is looped back. The COL signal will be inactive in this mode, unless collision test (bit 0.7) is active. The transmitters are powered down, regardless of the state of TXEN.
10/100 Ethernet MAC
TXD RXD
X
Digital Analog
TX RX
XFMR
CAT-5
X
SMSC
Ethernet Transceiver
Figure 5.1 Near-end Loopback Block Diagram
5.3.8.2
Far Loopback
Far loopback is a special test mode for MDI (analog) loopback as indicated by the blue arrows in Figure 5.3. The far loopback mode is enabled by setting bit register 17 bit 9 to logic one. In this mode, data that is received from the link partner on the MDI is looped back out to the link partner. The digital interface signals on the local MAC interface are isolated.
Far-end system
10/100 Ethernet MAC
TXD RXD
X X
Digital Analog
TX RX
XFMR
CAT-5
Link Partner
SMSC
Ethernet Transceiver
Figure 5.2 Far Loopback Block Diagram
5.3.8.3
Connector Loopback
The LAN8720/LAN8720i maintains reliable transmission over very short cables, and can be tested in a connector loopback as shown in Figure 5.3. An RJ45 loopback cable can be used to route the
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transmit signals an the output of the transformer back to the receiver inputs, and this loopback will work at both 10 and 100.
10/100 Ethernet MAC
TXD RXD
TX RX
XFMR
Digital
Analog
1 2 3 4 5 6 7 8
SMSC
Ethernet Transceiver
RJ45 Loopback Cable. Created by connecting pin 1 to pin 3 and connecting pin 2 to pin 6.
Figure 5.3 Connector Loopback Block Diagram
5.3.9
Configuration Signals
The hardware configuration signals are sampled during the power-on sequence to determine the physical address and operating mode.
5.3.9.1
Physical Address Bus - PHYAD[0]
The PHYAD0 bit is driven high or low to give each PHY a unique address. This address is latched into an internal register at the end of a hardware reset. In a multi-PHY application (such as a repeater), the controller is able to manage each PHY via the unique address. Each PHY checks each management data frame for a matching address in the relevant bits. When a match is recognized, the PHY responds to that particular frame. The PHY address is also used to seed the scrambler. In a multiPHY application, this ensures that the scramblers are out of synchronization and disperses the electromagnetic radiation across the frequency spectrum. The LAN8720 SMI address may be configured using hardware configuration to either the value 0 or 1. The user can configure the PHY address using Software Configuration if an address greater than 1 is required. The PHY address can be written (after SMI communication at some address is established) using the 10/100 Special Modes register (bits18.[4:0]). The PHYAD0 hardware configuration pin is multiplexed with the RXER pin. The LAN8720 may be configured to disregard the PHY address in SMI access write by setting the register bit 17.3 (PHYADBP).
5.3.9.2
Mode Bus - MODE[2:0]
The MODE[2:0] bus controls the configuration of the 10/100 digital block. When the nRST pin is deasserted, the register bit values are loaded according to the MODE[2:0] pins. The 10/100 digital block is then configured by the register bit values. When a soft reset occurs (bit 0.15) as described in Table 5.21, the configuration of the 10/100 digital block is controlled by the register bit values, and the MODE[2:0] pins have no affect. The LAN8720 mode may be configured using hardware configuration as summarized in Table 5.39. The user may configure the transceiver mode by writing the SMI registers.
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Table 5.39 MODE[2:0] Bus DEFAULT REGISTER BIT VALUES MODE[2:0] MODE DEFINITIONS REGISTER 0 [13,12,10,8] 000 001 010 10Base-T Half Duplex. Auto-negotiation disabled. 10Base-T Full Duplex. Auto-negotiation disabled. 100Base-TX Half Duplex. Auto-negotiation disabled. CRS is active during Transmit & Receive. 100Base-TX Full Duplex. Auto-negotiation disabled. CRS is active during Receive. 100Base-TX Half Duplex is advertised. Autonegotiation enabled. CRS is active during Transmit & Receive. Repeater mode. Auto-negotiation enabled. 100Base-TX Half Duplex is advertised. CRS is active during Receive. Power Down mode. In this mode the transceiver will wake-up in Power-Down mode. The transceiver cannot be used when the MODE[2:0] bits are set to this mode. To exit this mode, the MODE bits in Register 18.7:5(see Table 5.30) must be configured to some other value and a soft reset must be issued. All capable. Auto-negotiation enabled. 0000 0001 1000 REGISTER 4 [8,7,6,5] N/A N/A N/A
011 100
1001 1100
N/A 0100
101
1100
0100
110
N/A
N/A
111
X10X
1111
The MODE[2:0] hardware configuration pins are multiplexed with other signals as shown in Table 5.40.
Table 5.40 Pin Names for Mode Bits MODE BIT MODE[0] MODE[1] MODE[2] PIN NAME RXD0/MODE0 RXD1/MODE1 CRS_DV/MODE2
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Chapter 6 AC Electrical Characteristics
The timing diagrams and limits in this section define the requirements placed on the external signals of the Phy.
6.1
Serial Management Interface (SMI) Timing
The Serial Management Interface is used for status and control as described in Section 4.14.
T1.1 Clock MDC T1.2 Data Out MDIO T1.3 Data In MDIO T1.4 Valid Data (Write to PHY) Valid Data (Read from PHY)
Figure 6.1 SMI Timing Diagram
Table 6.1 SMI Timing Values PARAMETER T1.1 T1.2 T1.3 T1.4 DESCRIPTION MDC minimum cycle time MDC to MDIO (Read from PHY) delay MDIO (Write to PHY) to MDC setup MDIO (Write to PHY) to MDC hold MIN 400 0 10 10 30 TYP MAX UNITS ns ns ns ns NOTES
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6.2
RMII 10/100Base-TX/RX Timings (50MHz REF_CLK IN)
The 50MHz REF_CLK IN timing applies to the case when nINTSEL is floated or pulled-high on the LAN8720. In this mode, a 50MHz clock must be provided to the LAN8720 CLKIN pin. For more information on REF_CLK IN Mode, see Section 4.7.1.
6.2.1
6.2.1.1
RMII 100Base-T TX/RX Timings (50MHz REF_CLK IN)
100M RMII Receive Timing (50MHz REF_CLK IN)
Clock In CLKIN T6.1 Data Out RXD[1:0] CRS_DV Valid Data
Figure 6.2 100M RMII Receive Timing Diagram (50MHz REF_CLK IN)
Table 6.2 100M RMII Receive Timing Values (50MHz REF_CLK IN) PARAMETER T6.1 DESCRIPTION Output delay from rising edge of CLKIN to receive signals output valid CLKIN frequency MIN 3 TYP MAX 10 UNITS ns NOTES
50
MHz
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6.2.1.2
100M RMII Transmit Timing (50MHz REF_CLK IN)
Clock In CLKIN T8.1 Data In TXD[1:0] TX_EN T8.2 Valid Data
Figure 6.3 100M RMII Transmit Timing Diagram (50MHz REF_CLK IN)
Table 6.3 100M RMII Transmit Timing Values (50MHz REF_CLK IN) PARAMETER T8.1 T8.2 DESCRIPTION Transmit signals required setup to rising edge of CLKIN Transmit signals required hold after rising edge of CLKIN CLKIN frequency MIN 4 2 50 TYP MAX UNITS ns ns MHz NOTES
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6.2.2
6.2.2.1
RMII 10Base-T TX/RX Timings (50MHz REF_CLK IN)
10M RMII Receive Timing (50MHz REF_CLK IN)
Clock In CLKIN T9.1 Data Out RXD[1:0] CRS_DV Valid Data
Figure 6.4 10M RMII Receive Timing Diagram (50MHz REF_CLK IN) Table 6.4 10M RMII Receive Timing Values (50MHz REF_CLK IN) PARAMETER T9.1 DESCRIPTION Output delay from rising edge of CLKIN to receive signals output valid CLKIN frequency MIN 3 TYP MAX 10 UNITS ns NOTES
50
MHz
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6.2.2.2
10M RMII Transmit Timing (50MHz REF_CLK IN)
Clock In CLKIN T 10.1 Data In TXD[1:0] TX_EN T 10.2 Valid Data
Figure 6.5 10M RMII Transmit Timing Diagram (50MHz REF_CLK IN)
Table 6.5 10M RMII Transmit Timing Values (50MHz REF_CLK IN) PARAMETER T10.1 T10.2 DESCRIPTION Transmit signals required setup to rising edge of CLKIN Transmit signals required hold after rising edge of CLKIN CLKIN frequency MIN 4 2 50 TYP MAX UNITS ns ns MHz NOTES
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6.3
RMII 10/100Base-TX/RX Timings (50MHz REF_CLK OUT)
The 50MHz REF_CLK OUT timing applies to the case when LED/nINTSEL is pulled-low on the LAN8720. In this mode, a 25MHz crystal or clock oscillator must be provided to the LAN8720. For more information on 50MHz REF_CLK OUT mode, see Section 4.7.2
6.3.1
6.3.1.1
RMII 100Base-T TX/RX Timings (50MHz REF_CLK OUT)
100M RMII Receive Timing (50MHz REF_CLK OUT)
REFCLKO T11.1 Data Out RXD[1:0] CRS_DV Valid Data
Figure 6.6 100M RMII Receive Timing Diagram (50MHz REF_CLK OUT)
Table 6.6 100M RMII Receive Timing Values (50MHz REF_CLK OUT) PARAMETER T11.1 DESCRIPTION Output delay from rising edge of REFCLKO to receive signals output valid REFCLKO frequency MIN 1.5 TYP MAX 5 UNITS ns NOTES
50
MHz
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6.3.1.2
100M RMII Transmit Timing (50MHz REF_CLK OUT)
REFCLKO T12.1 Data In TXD[1:0] TX_EN T12.2 Valid Data
Figure 6.7 100M RMII Transmit Timing Diagram (50MHz REF_CLK OUT)
Table 6.7 100M RMII Transmit Timing Values (50MHz REF_CLK OUT) PARAMETER T12.1 T12.2 DESCRIPTION Transmit signals required setup to rising edge of REFCLKO Transmit signals required hold after rising edge of REFCLKO REFCLKO frequency MIN 7 2.5 50 TYP MAX UNITS ns ns MHz NOTES
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6.3.2
6.3.2.1
RMII 10Base-T TX/RX Timings (50MHz REF_CLK OUT)
10M RMII Receive Timing (50MHz REF_CLK OUT)
REFCLKO T13.1 Data Out RXD[1:0] CRS_DV Valid Data
Figure 6.8 10M RMII Receive Timing Diagram (50MHz REF_CLK OUT) Table 6.8 10M RMII Receive Timing Values (50MHz REF_CLK OUT) PARAMETER T13.1 DESCRIPTION Output delay from rising edge of REFCLKO to receive signals output valid REFCLKO frequency MIN 1.5 TYP MAX 5 UNITS ns NOTES
50
MHz
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6.3.2.2
10M RMII Transmit Timing (50MHz REF_CLK OUT)
REFCLKO T 14.1 Data In TXD[1:0] TX_EN T 14.2 Valid Data
Figure 6.9 10M RMII Transmit Timing Diagram (50MHz REF_CLK OUT)
Table 6.9 10M RMII Transmit Timing Values (50MHz REF_CLK OUT) PARAMETER T14.1 T14.2 DESCRIPTION Transmit signals required setup to rising edge of REFCLKO Transmit signals required hold after rising edge of REFCLKO CLKIN frequency MIN 7 2.5 50 TYP MAX UNITS ns ns MHz NOTES
6.4
RMII CLKIN Requirements
Table 6.10 RMII CLKIN (REF_CLK) Timing Values
PARAMETER
DESCRIPTION CLKIN frequency CLKIN Frequency Drift CLKIN Duty Cycle CLKIN Jitter
MIN
TYP 50
MAX
UNITS MHz
NOTES
50 40 60 150
ppm % psec p-p - not RMS
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6.5
Reset Timing
T 11.1 nRST T 11.2 Configuration Signals T 11.4 O utput drive T 11.3
Figure 6.10 Reset Timing Diagram
Table 6.11 Reset Timing Values PARAMETER T11.1 T11.2 T11.3 T11.4 DESCRIPTION Reset Pulse Width Configuration input setup to nRST rising Configuration input hold after nRST rising Output Drive after nRST rising MIN 100 200 10 20 800 TYP MAX UNITS us ns ns ns 20 clock cycles for 25 MHz clock or 40 clock cycles for 50MHz clock NOTES
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6.6
Clock Circuit
LAN8720/LAN8720i can accept either a 25MHz crystal or a 25MHz single-ended clock oscillator (50ppm) input. If the single-ended clock oscillator method is implemented, XTAL2 should be left unconnected and XTAL1/CLKIN should be driven with a nominal 0-3.3V clock signal. See Table 6.12 for the recommended crystal specifications.
Table 6.12 LAN8720/LAN8720i Crystal Specifications PARAMETER Crystal Cut Crystal Oscillation Mode Crystal Calibration Mode Frequency Frequency Tolerance @ 25oC Frequency Stability Over Temp Frequency Deviation Over Time Total Allowable PPM Budget Shunt Capacitance Load Capacitance Drive Level Equivalent Series Resistance Operating Temperature Range LAN8720/LAN8720i XTAL1/CLKIN Pin Capacitance LAN8720/LAN8720i XTAL2 Pin Capacitance Note 6.1 CO CL PW R1 Ffund Ftol Ftemp Fage SYMBOL MIN NOM AT, typ Fundamental Mode Parallel Resonant Mode 300 Note 6.4 25.000 +/-3 to 5 7 typ 20 typ 3 typ 3 typ 50 50 50 30 Note 6.5 MHz PPM PPM PPM PPM pF pF uW Ohm
oC
MAX
UNITS
NOTES
Note 6.1 Note 6.1 Note 6.2 Note 6.3
pF pF
Note 6.6 Note 6.6
The maximum allowable values for Frequency Tolerance and Frequency Stability are application dependant. Since any particular application must meet the IEEE 50 PPM Total PPM Budget, the combination of these two values must be approximately 45 PPM (allowing for aging). Frequency Deviation Over Time is also referred to as Aging. The total deviation for the Transmitter Clock Frequency is specified by IEEE 802.3u as 100 PPM. 0oC for extended commercial version, -40oC for industrial version. +85oC for extended commercial version, +85oC for industrial version. This number includes the pad, the bond wire and the lead frame. PCB capacitance is not included in this value. The XTAL1/CLKIN pin, XTAL2 pin and PCB capacitance values are required to accurately calculate the value of the two external load capacitors. The total load capacitance must be equivalent to what the crystal expects to see in the circuit so that the crystal oscillator will operate at 25.000 MHz.
Note 6.2 Note 6.3 Note 6.4 Note 6.5 Note 6.6
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Chapter 7 DC Electrical Characteristics
7.1
7.1.1
DC Characteristics
Maximum Guaranteed Ratings
Stresses beyond those listed in may cause permanent damage to the device. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Table 7.1 Maximum Conditions PARAMETER VDD1A, VDD2A, VDDIO Digital IO VSS Junction to Ambient (JA) Junction to Case (JC) Operating Temperature Operating Temperature Storage Temperature LAN8720-AEZG LAN8720i-AEZG 0 -40 -55 CONDITIONS Power pins to all other pins. MIN -0.5 TYP MAX +3.6 UNITS V COMMENT
To VSS ground VSS to all other pins Thermal vias per Layout Guidelines.
-0.5 -0.5
+3.6 +0.5 59.8 12.6 +85 +85 +150
V V
Table 7.6
C/W C/W
oC oC oC
Extended commercial temperature components. Industrial temperature components.
Table 7.2 ESD and LATCH-UP Performance PARAMETER CONDITIONS MIN TYP MAX UNITS COMMENTS
ESD PERFORMANCE All Pins System System Human Body Model IED61000-4-2 Contact Discharge IEC61000-4-2 Air-gap Discharge LATCH-UP PERFORMANCE All Pins EIA/JESD 78, Class II 150 mA 5 15 15 kV kV kV Device 3rd party system test 3rd party system test
7.1.1.1
Human Body Model (HBM) Performance
HBM testing verifies the ability to withstand the ESD strikes like those that occur during handling and manufacturing, and is done without power applied to the IC. To pass the test, the device must have
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no change in operation or performance due to the event. All pins on the LAN8720 provide +/-5kV HBM protection.
7.1.1.2
IEC61000-4-2 Performance
The IEC61000-4-2 ESD specification is an international standard that addresses system-level immunity to ESD strikes while the end equipment is operational. In contrast, the HBM ESD tests are performed at the device level with the device powered down. SMSC contracts with Independent laboratories to test the LAN8720 to IEC61000-4-2 in a working system. Reports are available upon request. Please contact your SMSC representative, and request information on 3rd party ESD test results. The reports show that systems designed with the LAN8720 can safely dissipate 15kV air discharges and 15kV contact discharges per the IEC61000-4-2 specification without additional board level protection. In addition to defining the ESD tests, IEC 61000-4-2 also categorizes the impact to equipment operation when the strike occurs (ESD Result Classification). The LAN8720 maintains an ESD Result Classification 1 or 2 when subjected to an IEC 61000-4-2 (level 4) ESD strike. Both air discharge and contact discharge test techniques for applying stress conditions are defined by the IEC61000-4-2 ESD document. AIR DISCHARGE To perform this test, a charged electrode is moved close to the system being tested until a spark is generated. This test is difficult to reproduce because the discharge is influenced by such factors as humidity, the speed of approach of the electrode, and construction of the test equipment. CONTACT DISCHARGE The uncharged electrode first contacts the pin to prepare this test, and then the probe tip is energized. This yields more repeatable results, and is the preferred test method. The independent test laboratories contracted by SMSC provide test results for both types of discharge methods.
7.1.2
Operating Conditions
Table 7.3 Recommended Operating Conditions
PARAMETER VDD1A, VDD2A VDDIO Input Voltage on Digital Pins Voltage on Analog I/O pins (RXP, RXN) Ambient Temperature
CONDITIONS To VSS ground To VSS ground
MIN 3.0 1.6 0.0 0.0
TYP 3.3 3.3
MAX 3.6 3.6 VDDIO +3.6V +85 +85
UNITS V V V V
o
COMMENT
TA LAN8720-AEZG TA LAN8720i-AEZG
0 -40
C
For Extended Commercial Temperature For Industrial Temperature
oC
7.1.3
7.1.3.1
Power Consumption
Power Consumption Device Only REF_CLK IN Mode
Power measurements taken over the operating conditions specified. See Section 5.3.5 for a description of the power down modes. For more information on REF_CLK IN Mode, see Section 4.7.1.
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Table 7.4 Power Consumption Device Only (REF_CLK IN MODE) VDDA3.3 POWER PINS(MA) Max 100BASE-T /W TRAFFIC Typical Min Max 10BASE-T /W TRAFFIC Typical Min Max ENERGY DETECT POWER DOWN Typical Min Max GENERAL POWER DOWN Typical Min 27.1 25.7 22.4 9.7 8.9 8.3 4.2 4.1 3.9 0.4 0.3 0.3 VDDCR POWER PIN(MA) 20.4 18.5 17.4 13 11.8 11.1 3 1.9 1.9 2.8 1.8 1.7 VDDIO POWER PIN(MA) 0.6 0.5 0.3 0.6 0.5 0.3 0.2 0.2 0 0.2 0.2 0 TOTAL CURRENT (MA) 48.1 44.7 40.1 23.3 21.2 19.7 7.4 6.2 5.8 3.4 2.3 2 TOTAL POWER (MW) 158.7 147.5 95.3 Note 7.1 76.9 70 41.3 Note 7.1 24.4 20.4 15.2 Note 7.1 11.2 7.6 3 Note 7.1
POWER PIN GROUP
Note: The current at VDDCR is either supplied by the internal regulator from current entering at VDD2A, or from an external 1.2V supply when the internal regulator is disabled. Note 7.1 Note 7.2 This is calculated with full flexPWR features activated: VDDIO = 1.8V and internal regulator disabled. Current measurements do not include power applied to the magnetics or the optional external LEDs.
7.1.3.2
Power Consumption Device Only 50MHz REF_CLK OUT Mode
Power measurements taken over the operating conditions specified. See Section 5.3.5 for a description of the power down modes. For more information on 50MHz REF_CLK OUT mode, see Section 4.7.2
.
Table 7.5 Power Consumption Device Only (50MHz REF_CLK OUT MODE) VDDA3.3 POWER PINS(MA) Max 100BASE-T /W TRAFFIC Typical Min 27.7 25.8 21.2 VDDCR POWER PIN(MA) 20 18.1 14.1 VDDIO POWER PIN(MA) 6.3 5.8 2.9 TOTAL CURRENT (MA) 54 49.7 38.2 TOTAL POWER (MW) 178.2 164 92.1 Note 7.3
POWER PIN GROUP
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Table 7.5 Power Consumption Device Only (50MHz REF_CLK OUT MODE) Max 10BASE-T /W TRAFFIC Typical Min Max ENERGY DETECT POWER DOWN Typical Min Max GENERAL POWER DOWN Typical Min 9.9 8.8 7.1 4.5 4 3.9 0.4 0.4 0.4 12.8 11.3 9.7 2.7 1.5 1.2 2.5 1.3 1 6.4 5.6 3 0.3 0.2 0 0.2 0.2 0 29.1 25.7 19.8 7.5 5.7 5.1 3.1 1.9 1.4 96 84.8 40.5 Note 7.3 24.8 18.8 14.3 Note 7.3 10.2 6.3 2.5 Note 7.3
Note: The current at VDDCR is either supplied by the internal regulator from current entering at VDD2A, or from an external 1.2V supply when the internal regulator is disabled. Note 7.3 Note 7.4 This is calculated with full flexPWR features activated: VDDIO = 1.8V and internal regulator disabled. Current measurements do not include power applied to the magnetics or the optional external LEDs.
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7.1.4
DC Characteristics - Input and Output Buffers
Table 7.6 RMII Bus Interface Signals NAME TXD0 TXD1 TXEN TXCLK RXD0/MODE0 RXD1/MODE1 RXER/PHYAD0 CRS_DV/MODE2 MDC MDIO nINT/REFCLKO 0.68 * VDDIO 0.68 * VDDIO 0.4 * VDDIO 0.4 * VDDIO -8 mA -8 mA +8 mA +8 mA +0.4 +0.4 VDDIO - +0.4 3.6 VIH (V) 0.68 * VDDIO 0.68 * VDDIO 0.68 * VDDIO VIL (V) 0.4 * VDDIO 0.4 * VDDIO 0.4 * VDDIO -8 mA -8 mA -8 mA -8 mA -8 mA +8 mA +8 mA +8 mA +8 mA +8 mA +0.4 +0.4 +0.4 +0.4 +0.4 VDDIO - +0.4 VDDIO - +0.4 VDDIO - +0.4 VDDIO - +0.4 VDDIO - +0.4 IOH IOL VOL (V) VOH (V)
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Table 7.7 LAN Interface Signals NAME TXP TXN RXP RXN See Table 7.12, "100Base-TX Transceiver Characteristics," on page 72 and Table 7.13, "10BASE-T Transceiver Characteristics," on page 72. VIH VIL IOH IOL VOL VOH
Table 7.8 LED Signals NAME LED1/REGOFF LED2/nINTSEL VIH (V) 0.63 * VDD2A 0.63 * VDD2A VIL (V) 0.39 * VDD2A 0.39 * VDD2A IOH -12 mA -12 mA IOL +12 mA +12 mA VOL (V) +0.4 +0.4 VOH (V) VDD2A - +0.4 VDD2A - +0.4
Table 7.9 Configuration Inputs NAME RXD0/MODE0 RXD1/MODE1 RXER/PHYAD0 CRS_DV/MODE2 VIH (V) 0.68 * VDDIO 0.68 * VDDIO 0.68 * VDDIO 0.68 * VDDIO VIL (V) 0.39 * VDDIO 0.39 * VDDIO 0.39 * VDDIO 0.39 * VDDIO IOH -8 mA -8 mA -8 mA -8 mA IOL +8 mA +8 mA +8 mA +8 mA VOL (V) +0.4 +0.4 +0.4 +0.4 VOH (V) VDDIO - +0.4 VDDIO - +0.4 VDDIO - +0.4 VDDIO - +0.4
Table 7.10 General Signals NAME nINT/REFCLKO nRST XTAL1/CLKIN (Note 7.5) XTAL2 Note 7.5 0.63 * VDDIO +1.40 V 0.39 * VDDIO 0.39 * VDD2A VIH (V) VIL (V) IOH -8 mA IOL +8 mA VOL (V) +0.4 VOH (V) VDDIO - +0.4
These levels apply when a 0-3.3V Clock is driven into XTAL1/CLKIN and XTAL2 is floating. The maximum input voltage on XTAL1/CLKIN is VDD2A + 0.4V.
Table 7.11 Internal Pull-Up / Pull-Down Configurations NAME TXEN RXD0/MODE0
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Table 7.11 Internal Pull-Up / Pull-Down Configurations (continued) NAME RXD1/MODE1 RXER/PHYAD0 CRS_DV/MODE2 LED1/REGOFF LED2/nINTSEL MDIO nINT/REFCLKO nRST PULL-UP OR PULL-DOWN Pull-up Pull-down Pull-up Pull-down Pull-up Pull-up Pull-up Pull-up Table 7.12 100Base-TX Transceiver Characteristics PARAMETER Peak Differential Output Voltage High Peak Differential Output Voltage Low Signal Amplitude Symmetry Signal Rise & Fall Time Rise & Fall Time Symmetry Duty Cycle Distortion Overshoot & Undershoot Jitter Note 7.6 Note 7.7 Note 7.8 SYMBOL VPPH VPPL VSS TRF TRFS DCD VOS MIN 950 -950 98 3.0 35 TYP 50 MAX 1050 -1050 102 5.0 0.5 65 5 1.4 UNITS mVpk mVpk % nS nS % % nS Note 7.8 NOTES Note 7.6 Note 7.6 Note 7.6 Note 7.6 Note 7.6 Note 7.7
Measured at the line side of the transformer, line replaced by 100 ( 1%) resistor. Offset from 16 nS pulse width at 50% of pulse peak Measured differentially.
Table 7.13 10BASE-T Transceiver Characteristics PARAMETER Transmitter Peak Differential Output Voltage Receiver Differential Squelch Threshold Note 7.9 SYMBOL VOUT VDS MIN 2.2 300 TYP 2.5 420 MAX 2.8 585 UNITS V mV NOTES Note 7.9
Min/max voltages guaranteed as measured with 100 resistive load.
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Chapter 8 Application Notes
8.1 Application Diagram
The LAN8720 requires few external components. The voltage on the magnetics center tap can range from 2.5 - 3.3V.
8.1.1
RMII Diagram
RMII
MDIO MDC nINT
LAN8720 10/100 PHY 24-QFN RMII Mag
TXP TXN RXP RXN
RJ45
TXD[1:0] 2 TXEN RXD[1:0] 2 RXER
XTAL1/CLKIN LED[2:1]
25MHz
2 nRST Interface XTAL2
Figure 8.1 Simplified Application Diagram
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8.1.2
Power Supply Diagram
Analog Supply 3.3V Power to magnetics interface.
6 1uF
LAN8720 24-QFN
VDDCR VDD1A
19 CBYPASS
VDDDIO Supply 1.8 - 3.3V CF R
9 CBYPASS
VDDIO
VDD2A
1 CBYPASS
15 C
RBIAS nRST
24
VSS
12k
Figure 8.3 High-Level System Diagram for Power
8.1.3
Twisted-Pair Interface Diagram
LAN8720 24-QFN
1
Analog Supply 3.3V
49.9 Resistors
Magnetic Supply 2.5 - 3.3V
VDD2A
CBYPASS 19 CBYPASS 21 75 Magnetics RJ45 TXP
1 2 3 4 5 6 7 8
VDD1A
TXN RXP
20 23 75
RXN
22
CBYPASS
1000 pF 3 kV
Figure 8.5 Copper Interface Diagram
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8.2
Magnetics Selection
For a list of magnetics selected to operate with the SMSC LAN8720, please refer to the Application note "AN 8-13 Suggested Magnetics". http://www.smsc.com/main/appnotes.html#Ethernet%20Products
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Chapter 9 Package Outline
Figure 9.1 LAN8720/LAN8720i-EZK 24-QFN Package Outline, 4 x 4 x 0.9 mm Body (Lead-Free)
Table 9.1 24 Terminal QFN Package Parameters MIN 0.70 0 ~ 3.85 3.55 2.40 3.85 3.55 2.40 0.30 0.18 ~ NOMINAL ~ 0.02 ~ 4.0 ~ 2.50 4.0 ~ 2.50 ~ 0.50 BSC 0.25 ~ MAX 1.00 0.05 0.90 4.15 3.95 2.60 4.15 3.95 2.60 0.50 0.30 0.08 REMARKS Overall Package Height Standoff Mold Thickness X Overall Size X Mold Cap Size X exposed Pad Size Y Overall Size Y Mold Cap Size Y exposed Pad Size Terminal Length Terminal Pitch Terminal Width Coplanarity
A A1 A2 D D1 D2 E E1 E2 L e b ccc
Notes: 1. Controlling Unit: millimeter. 2. Dimension b applies to plated terminals and is measured between 0.15mm and 0.30mm from the terminal tip. Tolerance on the true position of the leads is 0.05 mm at maximum material conditions (MMC). 3. Details of terminal #1 identifier are optional but must be located within the zone indicated. 4. Coplanarity zone applies to exposed pad and terminals.
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Figure 9.1 QFN, 4x4 Taping Dimensions and Part Orientation
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Figure 9.2 Reel Dimensions
Note: Standard reel size is 4000 pieces per reel.
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Chapter 10 Revision History
Table 10.1 Customer Revision History REVISION LEVEL & DATE Rev. 1.0 (05-28-09) Rev. 1.0 (04-15-09) Initial Release SECTION/FIGURE/ENTRY CORRECTION Revised LAN8720 ordering information.
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