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Preliminary Technical Data
FEATURES
5 kV rms Signal & Power Isolated RS-485 Transceiver with 15 kV ESD Protection ADM2682E/ADM2687E
FUNCTIONAL BLOCK DIAGRAM
VCC isoPower DC-TO-DC CONVERTER VISOOUT
5 kV rms isolated RS-485/RS-422 transceiver, configurable as half or full duplex isoPower(R) integrated isolated dc-to-dc converter 15 kV ESD protection on RS-485 input/output pins Complies with ANSI/TIA/EIA-485-A-98 and ISO 8482:1987(E) Data rate: 16 Mbps (ADM2682E), 500 kbps (ADM2687E) 5 V or 3.3 V operation Connect up to 256 nodes on one bus Open- and short-circuit, fail-safe receiver inputs High common-mode transient immunity: >25 kV/s Thermal shutdown protection Safety and regulatory approvals UL recognition (pending) 5000 V rms for 1 minute per UL 1577 CSA Component Acceptance Notice #5A (pending) IEC 60601-1: 400 V rms (basic), 250 V rms (reinforced) IEC 60950-1: 600 V rms (basic), 380 V rms (reinforced) VDE Certificates of Conformity (pending) DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01 VIORM = 846 V peak Operating temperature range: -40C to +85C 16-lead wide-body SOIC with >8 mm creepage and clearance
OSCILLATOR
RECTIFIER
REGULATOR
VISOIN
DIGITAL ISOLATION iCoupler ENCODE DECODE
TRANSCEIVER Y
TxD
D Z
DE
ENCODE
DECODE
A RxD DECODE ENCODE R B
RE GND1
ADM2682E/ADM2687E
ISOLATION BARRIER GND2
Figure 1.
APPLICATIONS
Isolated RS-485/RS-422 interfaces Industrial field networks Multipoint data transmission systems
GENERAL DESCRIPTION
The ADM2682E/ADM2687E are fully integrated 5 kV rms signal and power isolated data transceivers with 15 kV ESD protection and are suitable for high speed communication on multipoint transmission lines. The ADM2682E/ADM2687E include an integrated 5 kV rms isolated dc-to-dc power supply, which eliminates the need for an external dc-to-dc isolation block. They are designed for balanced transmission lines and comply with ANSI/TIA/EIA-485-A-98 and ISO 8482:1987(E). The devices integrate Analog Devices, Inc., iCoupler(R) technology to combine a 3-channel isolator, a three-state differential line driver, a differential input receiver, and Analog Devices isoPower dc-todc converter into a single package. The devices are powered by a single 5 V or 3.3 V supply, realizing a fully integrated signal and power isolated RS-485 solution.
Rev. PrE
The ADM2682E/ADM2687E driver has an active high enable. An active low receiver enable is also provided, which causes the receiver output to enter a high impedance state when disabled. The devices have current limiting and thermal shutdown features to protect against output short circuits and situations where bus contention may cause excessive power dissipation. The parts are fully specified over the industrial temperature range and are available in a highly integrated, 16-lead, widebody SOIC package with >8 mm creepage and clearance. The ADM2682E/ADM2687E contain isoPower technology that uses high frequency switching elements to transfer power through the transformer. Special care must be taken during printed circuit board (PCB) layout to meet emissions standards. Refer to Application Note AN-0971, Control of Radiated Emissions with isoPower Devices, for details on board layout considerations.
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
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ADM2682E/ADM2687E TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Specifications..................................................................................... 3 ADM2682E Timing Specifications ............................................ 4 ADM2687E Timing Specifications ............................................ 4 ADM2682E/ADM2687E Package Characteristics ................... 4 ADM2682E/ADM2687E Regulatory Information .................. 5 ADM2682E/ADM2687E Insulation and Safety-Related Specifications ................................................................................ 5 ADM2682E/ADM2687E VDE 0884 Insulation Characteristics (Pending) ............................................................ 6 Absolute Maximum Ratings............................................................ 7 ESD Caution .................................................................................. 7 Pin Configuration and Function Descriptions ............................. 8 Typical Performance Characteristics ............................................. 9
Preliminary Technical Data
Test Circuits..................................................................................... 13 Switching Characteristics .............................................................. 14 Circuit Description......................................................................... 15 Signal Isolation ........................................................................... 15 Power Isolation ........................................................................... 15 Truth Tables................................................................................. 15 Thermal Shutdown .................................................................... 15 Open- and Short-Circuit, Fail-Safe Receiver Inputs.............. 15 DC Correctness and Magnetic Field Immunity .......................... 16 Applications Information .............................................................. 17 PCB Layout ................................................................................. 17 EMI Considerations ................................................................... 17 Insulation Lifetime ..................................................................... 17 Typical Applications ................................................................... 18 Outline Dimensions ....................................................................... 20 Ordering Guide .......................................................................... 20
Rev. PrE | Page 2 of 20
Preliminary Technical Data SPECIFICATIONS
ADM2682E/ADM2687E
All voltages are relative to their respective ground; 3.0 VCC 5.5 V. All minimum/maximum specifications apply over the entire recommended operation range, unless otherwise noted. All typical specifications are at TA = 25C, VCC = 5 V unless otherwise noted. Table 1.
Parameter ADM2687E SUPPLY CURRENT Data Rate 500 kbps Symbol ICC Min Typ 90 72 125 98 120 ADM2682E SUPPLY CURRENT Data Rate = 16 Mbps ISOLATED SUPPLY VOLTAGE DRIVER Differential Outputs Differential Output Voltage, Loaded ICC 150 230 VISOUT 3.3 mA mA 120 load between Y and Z 54 load between Y and Z Max Unit mA mA mA mA mA Test Conditions VCC = 3.3 V, 100 load between Y and Z VCC = 5 V, 100 load between Y and Z VCC = 3.3 V, 54 load between Y and Z VCC = 5 V, 54 load between Y and Z 120 load between Y and Z
|VOD2| |VOD3| |VOD| VOC |VOC| IOS IO
2.0 1.5 1.5
|VOD| for Complementary Output States Common-Mode Output Voltage |VOC| for Complementary Output States Short-Circuit Output Current Output Leakage Current (Y, Z) Logic Inputs DE, RE, TxD Input Threshold Low Input Threshold High Input Current RECEIVER Differential Inputs Differential Input Threshold Voltage Input Voltage Hysteresis Input Current (A, B) Line Input Resistance Logic Outputs Output Voltage Low Output Voltage High Short-Circuit Current COMMON-MODE TRANSIENT IMMUNITY 1
1
3.6 3.6 3.6 0.2 3.0 0.2 200 30
V V V V V V mA A A
-30
DE = 0 V, = 0 V, VCC = 0 V or 3.6 V, RE VIN = 12 V DE = 0 V, = 0 V, VCC = 0 V or 3.6 V, RE VIN = -7 V DE, RE, TxD DE, RE, TxD DE, RE, TxD
RL = 100 (RS-422), see Figure 23 RL = 54 (RS-485), see Figure 23 -7 V VTEST1 12 V, see Figure 24 RL = 54 or 100 , see Figure 23 RL = 54 or 100 , see Figure 23 RL = 54 or 100 , see Figure 23
VIL VIH II
0.3 x VCC -10 0.01 0.7 x VCC 10
V V A
VTH VHYS II RIN VOL VOH
-200
-125 15
-30 125
-100 96 0.2 VCC - 0.2 0.4 100 25
mV mV A A k V V mA kV/s
-7 V < VCM < +12 V VOC = 0 V DE = 0 V, VCC = 0 V or 3.6 V, VIN = 12 V DE = 0 V, VCC = 0 V or 3.6 V, VIN = -7 V -7 V < VCM < +12 V IO = 1.5 mA, VA - VB = -0.2 V IO = -1.5 mA, VA - VB = 0.2 V VCM = 1 kV, transient magnitude = 800 V
VCC - 0.3
CM is the maximum common-mode voltage slew rate that can be sustained while maintaining specification-compliant operation. VCM is the common-mode potential difference between the logic and bus sides. The transient magnitude is the range over which the common-mode is slewed. The common-mode voltage slew rates apply to both rising and falling common-mode voltage edges.
Rev. PrE | Page 3 of 20
ADM2682E/ADM2687E
ADM2682E TIMING SPECIFICATIONS
TA = -40C to +85C. Table 2.
Parameter DRIVER Maximum Data Rate Propagation Delay, Low to High Propagation Delay, High to Low Output Skew Rise Time/Fall Time Enable Time Disable Time RECEIVER Propagation Delay, Low to High Propagation Delay, High to Low Output Skew 1 Enable Time Disable Time
1
Preliminary Technical Data
Symbol
Min 16
Typ
Max
Unit Mbps ns ns ns ns ns ns ns ns ns ns ns
Test Conditions
tDPLH tDPHL tSKEW tDR, tDF tZL, tZH tLZ, tHZ tRPLH tRPHL tSKEW tZL, tZH tLZ, tHZ
63 64 1
100 100 8 15 120 150 110 110 12 15 15
RL = 54 , CL1 = C L2 = 100 pF, see Figure 25 and Figure 29 RL = 54 , CL1 = C L2 = 100 pF, see Figure 25 and Figure 29 RL = 54 , CL1 = CL2 = 100 pF, see Figure 25 and Figure 29 RL = 54 , CL1 = CL2 = 100 pF, see Figure 25 and Figure 29 RL = 110 , CL = 50 pF, see Figure 26 and Figure 31 RL = 110 , CL = 50 pF, see Figure 26 and Figure 31 CL = 15 pF, see Figure 27 and Figure 30 CL = 15 pF, see Figure 27 and Figure 30 CL = 15 pF, see Figure 27 and Figure 30 RL = 1 k, CL = 15 pF, see Figure 28 and Figure 32 RL = 1 k, CL = 15 pF, see Figure 28 and Figure 32
94 95 1
Guaranteed by design.
ADM2687E TIMING SPECIFICATIONS
TA = -40C to +85C. Table 3.
Parameter DRIVER Maximum Data Rate Propagation Delay, Low to High Propagation Delay, High to Low Output Skew Rise Time/Fall Time Enable Time Disable Time RECEIVER Propagation Delay, Low to High Propagation Delay, High to Low Output Skew Enable Time Disable Time Symbol Min 500 250 250 200 Typ Max Unit kbps ns ns ns ns s ns ns ns ns ns ns Test Conditions
tDPLH tDPHL tSKEW tDR, tDF tZL, tZH tLZ, tHZ tRPLH tRPHL tSKEW tZL, tZH tLZ, tHZ
503 510 7
700 700 100 1100 2.5 200 200 200 30 15 15
RL = 54 , CL1 = C L2 = 100 pF, see Figure 25 and Figure 29 RL = 54 , CL1 = C L2 = 100 pF, see Figure 25 and Figure 29 RL = 54 , CL1 = CL2 = 100 pF, see Figure 25 and Figure 29 RL = 54 , CL1 = CL2 = 100 pF, see Figure 25 and Figure 29 RL = 110 , CL = 50 pF, see Figure 26 and Figure 31 RL = 110 , CL = 50 pF, see Figure 26 and Figure 31 CL = 15 pF, see Figure 27 and Figure 30 CL = 15 pF, see Figure 27 and Figure 30 CL = 15 pF, see Figure 27 and Figure 30 RL = 1 k, CL = 15 pF, see Figure 28 and Figure 32 RL = 1 k, CL = 15 pF, see Figure 28 and Figure 32
91 95 4
ADM2682E/ADM2687E PACKAGE CHARACTERISTICS
Table 4.
Parameter Resistance (Input-to-Output) 1 Capacitance (Input-to-Output)1 Input Capacitance 2
1 2
Symbol RI-O CI-O CI
Min
Typ 1012 3 4
Max
Unit pF pF
Test Conditions f = 1 MHz
Device considered a 2-terminal device: short together Pin 1 to Pin 8 and short together Pin 9 to Pin 16. Input capacitance is from any input data pin to ground.
Rev. PrE | Page 4 of 20
Preliminary Technical Data
ADM2682E/ADM2687E REGULATORY INFORMATION
Table 5. ADM2682E/ADM2687E Approvals
Organization UL (Pending)
ADM2682E/ADM2687E
Approval Type To be recognized under the UL 1577 Component Recognition Program of Underwriters Laboratories, Inc. Single Protection, 5000 V rms isolation voltage In accordance with UL 1577, each ADM2682E/ADM2687E is proof tested by applying an insulation test voltage 6000 V rms for 1 second. To be approved under CSA Component Acceptance Notice #5A Reinforced insulation per IEC 60601-1, 250 V rms(353 V peak) maximum working voltage Basic insulation per IEC 60601-1, 400 V rms (566 V peak) maximum working voltage Reinforced insulation per CSA 60950-1-03 and IEC 60950-1, 380 V rms (537 V peak) maximum working voltage Basic insulation per CSA 60950-1-03 and IEC 60950-1, 600 V rms (848 V peak) maximum working voltage To be certified according to DIN EN 60747-5-2 (VDE 0884 Rev. 2): 2003-01 In accordance with DIN EN 60747-5-2, each ADM2682E/ADM2687E is proof tested by applying an insulation test voltage 1590 VPEAK for 1 second.
CSA (Pending)
VDE (Pending)
ADM2682E/ADM2687E INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 6.
Parameter Rated Dielectric Insulation Voltage Minimum External Air Gap (Clearance) Minimum External Tracking (Creepage) Minimum Internal Gap (Internal Clearance) Tracking Resistance (Comparative Tracking Index) Isolation Group Symbol L(I01) L(I02) Value 5000 >8.0 >8.0 0.017 min >175 IIIa Unit V rms mm mm mm V Conditions 1-minute duration Measured from input terminals to output terminals, shortest distance through air Measured from input terminals to output terminals, shortest distance along body Insulation distance through insulation DIN IEC 112/VDE 0303-1 Material Group (DIN VDE 0110: 1989-01, Table 1)
CTI
Rev. PrE | Page 5 of 20
ADM2682E/ADM2687E
Preliminary Technical Data
ADM2682E/ADM2687E VDE 0884 INSULATION CHARACTERISTICS (PENDING)
This isolator is suitable for reinforced electrical isolation only within the safety limit data. Maintenance of the safety data must be ensured by means of protective circuits. Table 7.
Description CLASSIFICATIONS Installation Classification per DIN VDE 0110 for Rated Mains Voltage 300 V rms 450 V rms 600 V rms Climatic Classification Pollution Degree VOLTAGE Maximum Working Insulation Voltage Input-to-Output Test Voltage Method b1 Method a After Environmental Tests, Subgroup 1 After Input and/or Safety Test, Subgroup 2/Subgroup 3 Highest Allowable Overvoltage SAFETY-LIMITING VALUES Case Temperature Input Current Output Current Insulation Resistance at TS Conditions Symbol Characteristic Unit
DIN VDE 0110, see Table 1 VIORM VPR VIORM x 1.875 = VPR, 100% production tested, tm = 1 sec, partial discharge < 5 pC VIORM x 1.6 = VPR, tm = 60 sec, partial discharge < 5 pC VIORM x 1.2 = VPR, tm = 60 sec, partial discharge < 5 pC Transient overvoltage, tTR = 10 sec Maximum value allowed in the event of a failure VTR TS IS, INPUT IS, OUTPUT RS
I to IV I to III I to II 40/85/21 2 846 1590 V peak V peak
1375 1018 6000 150 265 335 >109
V peak V peak V peak C mA mA
VIO = 500 V
Rev. PrE | Page 6 of 20
Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS
TA = 25C, unless otherwise noted. All voltages are relative to their respective ground. Table 8.
Parameter VCC Digital Input Voltage (DE, , TxD) RE Digital Output Voltage (RxD) Driver Output/Receiver Input Voltage Operating Temperature Range Storage Temperature Range ESD (Human Body Model) on A, B, Y, and Z pins ESD (Human Body Model) on Other Pins Thermal Resistance JA Lead Temperature Soldering (10 sec) Vapor Phase (60 sec) Infrared (15 sec) Rating -0.5 V to +7 V -0.5 V to VDD + 0.5 V -0.5 V to VDD + 0.5 V -9 V to +14 V -40C to +85C -55C to +150C 15 kV 2 kV 52C/W 260C 215C 220C
ADM2682E/ADM2687E
Table 9. Maximum Continuous Working Voltage1
Parameter AC Voltage Bipolar Waveform Max 424 Unit V peak Reference Standard All certifications, 50-year minimum lifetime
Unipolar Waveform Basic Insulation Reinforced Insulation
600 537
V peak V peak
Maximum approved working voltage per IEC 60950-1
DC Voltage Basic Insulation Reinforced Insulation
600 537
V peak V peak
Maximum approved working voltage per IEC 60950-1
1
Refers to continuous voltage magnitude imposed across the isolation barrier. See the Insulation Lifetime section for more details.
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ESD CAUTION
Rev. PrE | Page 7 of 20
ADM2682E/ADM2687E PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
GND1 1 VCC 2 RxD 3 RE 4
16 GND2 15 VISOIN 14 A
Preliminary Technical Data
13 B TOP VIEW DE 5 (Not to Scale) 12 Z 11 Y 10 VISOOUT 9
ADM2682E ADM2687E
TxD 6 VCC 7 GND1 8
GND2
NOTES: 1. PIN 10 AND PIN 15 MUST BE CONNECTED EXTERNALLY
Figure 2. Pin Configuration
Table 10. Pin Function Description
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Mnemonic GND1 VCC RE RxD Description Ground, Logic Side. Logic Side Power Supply. It is recommended that a 0.1 F and a 0.01 F decoupling capacitor be fitted between Pin 2 and Pin 1. Receiver Output Data. This output is high when (A - B) -30 mV and low when (A - B) -200 mV. The output is tristated when the receiver is disabled, that is, when RE is driven high. Receiver Enable Input. This is an active-low input. Driving this input low enables the receiver; driving it high disables the receiver. Driver Enable Input. Driving this input high enables the driver; driving it low disables the driver. Driver Input. Data to be transmitted by the driver is applied to this input. Logic Side Power Supply. It is recommended that a 0.1 F and a 10 F decoupling capacitor be fitted between Pin 7 and Pin 8. Ground, Logic Side. Ground, Bus Side. Isolated Power Supply Output. This pin must be connected externally to VISOIN. It is recommended that a reservoir capacitor of 10 F and a decoupling capacitor of 0.1 F be fitted between Pin 10 and Pin 9. Driver Noninverting Output Driver Inverting Output Receiver Inverting Input. Receiver Noninverting Input. Isolated Power Supply Input. This pin must be connected externally to VISOOUT. It is recommended that a 0.1 F and a 0.01 F decoupling capacitor be fitted between Pin 15 and Pin 16. Ground, Bus Side.
DE TxD VCC GND1 GND2 VISOOUT Y Z B A VISOIN GND2
Rev. PrE | Page 8 of 20
Preliminary Technical Data TYPICAL PERFORMANCE CHARACTERISTICS
180 160
ADM2682E/ADM2687E
140 120 RL = 54
SUPPLY CURRENT, ICC (mA)
SUPPLY CURRENT, ICC (mA)
140 120
RL = 54
100 80 60 40 NO LOAD 20 0 -40
RL = 120 100 80 60 40 20
08111-103
RL = 120
NO LOAD
-15
10 35 TEMPERATURE (C)
60
85
-15
10 35 TEMPERATURE (C)
60
85
Figure 3. ADM2682E Supply Current (ICC) vs. Temperature (Data Rate = 16 Mbps, DE = 3.3 V, VCC = 3.3 V)
140 120 RL = 54
Figure 6. ADM2687E Supply Current (ICC) vs. Temperature (Data Rate = 500 kbps, DE = 3.3 V, VCC = 3.3 V)
72 70
DRIVER PROPAGATION DELAY (ns)
68 66 64 62 60 58 56 54 52
SUPPLY CURRENT, ICC (mA)
100 RL = 120 80 60 NO LOAD 40 20 0 -40
tDPHL tDPLH
08111-104
-15
10 35 TEMPERATURE (C)
60
85
-15
10 35 TEMPERATURE (C)
60
85
Figure 4. ADM2682E Supply Current (ICC) vs. Temperature (Data Rate = 16 Mbps, DE = 5 V, VCC = 5 V)
120
Figure 7. ADM2682E Differential Driver Propagation Delay vs. Temperature
600 580
100
DRIVER PROPAGATION DELAY (ns)
SUPPLY CURRENT, ICC (mA)
RL = 54 80 RL = 120
560 540
tDPLH
520 500 480 460 440 420
tDPHL
60
40 NO LOAD 20
08111-106
-15
10 35 TEMPERATURE (C)
60
85
-15
10 35 TEMPERATURE (C)
60
85
Figure 5. ADM2687E Supply Current (ICC) vs. Temperature (Data Rate = 500 kbps, DE = 5 V, VCC = 5 V)
Figure 8. ADM2687E Differential Driver Propagation Delay vs. Temperature
Rev. PrE | Page 9 of 20
08111-108
0 -40
400 -40
08111-107
50 -40
08111-105
0 -40
ADM2682E/ADM2687E
60
TxD
Preliminary Technical Data
50
OUTPUT CURRENT (mA)
08111-109
40
1
30
Z Y
3
20
10
0
1
2 3 OUTPUT VOLTAGE (V)
4
5
Figure 9. ADM2682E Driver Propagation Delay
Figure 12. Receiver Output Current vs. Receiver Output Low Voltage
4.75 4.74 4.73
OUTPUT VOLTAGE(V)
4.72 4.71 4.70 4.69 4.68 4.67 4.66
TxD
1
Z Y
3
08111-110
-15
10 35 TEMPERATURE (C)
60
85
Figure 10. ADM2687E Driver Propagation Delay
0
Figure 13. Receiver Output High Voltage vs. Temperature
0.32
-10
0.30
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
-20
0.28
-30
0.26
-40
0.24
-50
-60
0.22
08111-111
0
1
2 3 OUTPUT VOLTAGE (V)
4
5
-15
10 35 TEMPERATURE (C)
60
85
Figure 11. Receiver Output Current vs. Receiver Output High Voltage
Figure 14. Receiver Output Low Voltage vs. Temperature
Rev. PrE | Page 10 of 20
08111-114
-70
0.20 -40
08111-113
CH1 2.0V CH3 2.0V
CH2 2.0V
M200ns
A CH1
2.56V
4.65 -40
08111-112
CH1 2.0V CH3 2.0V
CH2 2.0V
M10.00ns
A CH1
1.28V
0
Preliminary Technical Data
100
B
ADM2682E/ADM2687E
RECEIVER PROPAGATION DELAY (ns)
99 98 97 96 95 94 93 92 91
08111-118
A
1
tRPHL
RxD
3
tRPLH
CH1 2.0V CH3 2.0V
CH2 2.0V
M10.00ns
A CH1
2.56V
08111-115
90 -40
-15
10 35 TEMPERATURE (C)
60
85
Figure 15. ADM2682E Receiver Propagation Delay
Figure 18. ADM2687E Receiver Propagation Delay vs. Temperature
3.33
A
ISOLATED SUPPLY VOLTAGE (V)
3.32
3.31
B
1
3.30
3.29 NO LOAD RL = 120 RL = 54
3.28
RxD
3
3.27
08111-116
CH1 2.0V CH3 2.0V
CH2 2.0V
M10.00ns
A CH1
2.56V
-15
10 35 TEMPERATURE (C)
60
85
Figure 16. ADM2687E Receiver Propagation Delay
98
Figure 19. ADM2682E Isolated Supply Voltage vs. Temperature (VCC = 3.3 V, Data Rate = 16 Mbps)
3.36 3.35
RECEIVER PROPAGATION DELAY (ns)
ISOLATED SUPPLY VOLTAGE (V)
97
3.34 3.33 3.32 3.31 3.30 3.29 3.28 3.27 NO LOAD RL = 120 RL = 54 -15 10 35 TEMPERATURE (C) 60 85
08111-120
96
tRPHL
95
tRPLH
94
93
-15
10 35 TEMPERATURE (C)
60
85
Figure 17. ADM2682E Receiver Propagation Delay vs. Temperature
08111-117
92 -40
3.26 -40
Figure 20. ADM2682E Isolated Supply Voltage vs. Temperature (VCC = 5 V, Data Rate = 16 Mbps)
Rev. PrE | Page 11 of 20
08111-119
3.26 -40
ADM2682E/ADM2687E
60 RL = 54 40 35
Preliminary Technical Data
RL = 54
ISOLATED SUPPLY CURRENT (mA)
50
ISOLATED SUPPLY CURRENT (mA)
30 25 20 15 10 NO LOAD 5 RL = 120
40 RL = 120 30
20
NO LOAD
10
-15
10 35 TEMPERATURE (C)
60
85
08111-121
-15
10 35 TEMPERATURE (C)
60
85
Figure 21. ADM2682E Isolated Supply Current vs. Temperature (VCC = 3.3 V, Data Rate = 16 Mbps)
Figure 22. ADM2687E Isolated Supply Current vs. Temperature (VCC = 3.3 V, Data Rate = 500 kbps)
Rev. PrE | Page 12 of 20
08111-122
0 -40
0 -40
Preliminary Technical Data TEST CIRCUITS
Y
TxD VOD2 RL 2 RL 2
ADM2682E/ADM2687E
VOUT Y
VOC
VCC
Z
TxD
08111-003
RL 110 S1 S2
08111-006
DE
Z
CL 50pF
Figure 23. Driver Voltage Measurement
Figure 26. Driver Enable/Disable
Y
TxD VOD3 60
375
A
Z
375
08111-004
VTEST
Figure 24. Driver Voltage Measurement
Figure 27. Receiver Propagation Delay
Y
TxD RL
CL
+1.5V S1 RL RE
08111-005
VCC
Z
CL
-1.5V CL VOUT
08111-007
B
RE
VOUT CL
S2
08111-008
RE IN
Figure 25. Driver Propagation Delay
Figure 28. Receiver Enable/Disable
Rev. PrE | Page 13 of 20
ADM2682E/ADM2687E SWITCHING CHARACTERISTICS
VCC VCC/2 0V VCC/2
Preliminary Technical Data
tDPLH
Z 1/2VO VO Y
tDPHL
DE
VCC
0.5VCC
0.5VCC 0V
tZL
2.3V
tLZ
+VO VDIFF -VO
Y, Z
90% POINT
VDIFF = V(Y) - V(Z)
90% POINT
VOL + 0.5V
VOL
tZH
08111-009
2.3V
tHZ
VOH VOH - 0.5V
08111-011
10% POINT
10% POINT
tDR
tDF
Y, Z
tSKEW = tDPHL - tDPLH
Figure 29. Driver Propagation Delay, Rise/Fall Timing
Figure 31. Driver Enable/Disable Timing
0.7VCC
RE
A-B 0V 0V
0.5VCC
0.5VCC
0.3VCC
tZL
1.5V
tLZ
tRPLH
tRPHL
VOH
RO
OUTPUT LOW
VOL + 0.5V VOL
tZH
OUTPUT HIGH
RO 0V
tHZ
VOH - 0.5V VOH
08111-012
RxD
1.5V
tSKEW = |tRPLH - tRPHL |
1.5V
VOL
08111-010
1.5V
Figure 30. Receiver Propagation Delay
Figure 32. Receiver Enable/Disable Timing
Rev. PrE | Page 14 of 20
Preliminary Technical Data CIRCUIT DESCRIPTION
SIGNAL ISOLATION
The ADM2682E/ADM2687E signal isolation of 5 kV rms is implemented on the logic side of the interface. The part achieves signal isolation by having a digital isolation section and a transceiver section (see Figure 1). Data applied to the TxD and DE pins and referenced to logic ground (GND1) are coupled across an isolation barrier to appear at the transceiver section referenced to isolated ground (GND2). Similarly, the single-ended receiver output signal, referenced to isolated ground in the transceiver section, is coupled across the isolation barrier to appear at the RXD pin referenced to logic ground.
ADM2682E/ADM2687E
Table 13. Receiving (see Table 11 for Abbreviations)
Inputs A-B -0.03 V -0.2 V -0.2 V < A - B < -0.03 V Inputs open X RE L or NC L or NC L or NC L or NC H Output RxD H L I H Z
THERMAL SHUTDOWN
The ADM2682E/ADM2687E contain thermal shutdown circuitry that protects the parts from excessive power dissipation during fault conditions. Shorting the driver outputs to a low impedance source can result in high driver currents. The thermal sensing circuitry detects the increase in die temperature under this condition and disables the driver outputs. This circuitry is designed to disable the driver outputs when a die temperature of 150C is reached. As the device cools, the drivers are reenabled at a temperature of 140C.
POWER ISOLATION
The ADM2682E/ADM2687E power isolation of 5 kV rms is implemented using an isoPower integrated isolated dc-to-dc converter. The dc-to-dc converter section of the ADM2682E/ADM2687E works on principles that are common to most modern power supplies. It is a secondary side controller architecture with isolated pulse-width modulation (PWM) feedback. VCC power is supplied to an oscillating circuit that switches current into a chip-scale air core transformer. Power transferred to the secondary side is rectified and regulated to 3.3 V. The secondary (VISO) side controller regulates the output by creating a PWM control signal that is sent to the primary (VCC) side by a dedicated iCoupler (5 kV rms signal isolated) data channel. The PWM modulates the oscillator circuit to control the power being sent to the secondary side. Feedback allows for significantly higher power and efficiency.
OPEN- AND SHORT-CIRCUIT, FAIL-SAFE RECEIVER INPUTS
The receiver inputs have open- and short-circuit, fail-safe features that ensure that the receiver output is high when the inputs are open or shorted. During line-idle conditions, when no driver on the bus is enabled, the voltage across a terminating resistance at the receiver input decays to 0 V. With traditional transceivers, receiver input thresholds specified between -200 mV and +200 mV mean that external bias resistors are required on the A and B pins to ensure that the receiver outputs are in a known state. The short-circuit, fail-safe receiver input feature eliminates the need for bias resistors by specifying the receiver input threshold between -30 mV and -200 mV. The guaranteed negative threshold means that when the voltage between A and B decays to 0 V, the receiver output is guaranteed to be high.
TRUTH TABLES
The truth tables in this section use the abbreviations found in Table 11. Table 11. Truth Table Abbreviations
Letter H L X I Z NC Description High level Low level Don't care Indeterminate High impedance (off ) Disconnected
Table 12. Transmitting (see Table 11 for Abbreviations)
Inputs DE H H L X TxD H L X X Y H L Z Z Outputs Z L H Z Z
Rev. PrE | Page 15 of 20
ADM2682E/ADM2687E
The digital signals transmit across the isolation barrier using iCoupler technology. This technique uses chip-scale transformer windings to couple the digital signals magnetically from one side of the barrier to the other. Digital inputs are encoded into waveforms that are capable of exciting the primary transformer winding. At the secondary winding, the induced waveforms are decoded into the binary value that was originally transmitted. Positive and negative logic transitions at the isolator input cause narrow (~1 ns) pulses to be sent to the decoder via the transformer. The decoder is bistable and is, therefore, either set or reset by the pulses, indicating input logic transitions. In the absence of logic transitions at the input for more than 1 s, periodic sets of refresh pulses indicative of the correct input state are sent to ensure dc correctness at the output. If the decoder receives no internal pulses of more than approximately 5 s, the input side is assumed to be unpowered or nonfunctional, in which case, the isolator output is forced to a default state by the watchdog timer circuit. This situation should occur in the ADM2682E/ADM2687E devices only during power-up and power-down operations. The limitation on the ADM2682E/ADM2687E magnetic field immunity is set by the condition in which induced voltage in the transformer receiving coil is sufficiently large to either falsely set or reset the decoder. The following analysis defines the conditions under which this can occur. The 3.3 V operating condition of the ADM2682E/ADM2687E is examined because it represents the most susceptible mode of operation. The pulses at the transformer output have an amplitude of >1.0 V. The decoder has a sensing threshold of about 0.5 V, thus establishing a 0.5 V margin in which induced voltages can be tolerated. The voltage induced across the receiving coil is given by V = (-d/dt)rn2; n = 1, 2, ... , N where: is magnetic flux density (gauss). N is the number of turns in the receiving coil. rn is the radius of the nth turn in the receiving coil (cm). Given the geometry of the receiving coil in the ADM2682E/ ADM2687E and an imposed requirement that the induced voltage be, at most, 50% of the 0.5 V margin at the decoder, a maximum allowable magnetic field is calculated as shown in Figure 33.
MAXIMUM ALLOWABLE MAGNETIC FLUX DENSITY (kGauss)
Preliminary Technical Data
100
DC CORRECTNESS AND MAGNETIC FIELD IMMUNITY
10
1
0.1
0.01
1M 10k 10M 100k MAGNETIC FIELD FREQUENCY (Hz)
100M
Figure 33. Maximum Allowable External Magnetic Flux Density
For example, at a magnetic field frequency of 1 MHz, the maximum allowable magnetic field of 0.2 kgauss induces a voltage of 0.25 V at the receiving coil. This is about 50% of the sensing threshold and does not cause a faulty output transition. Similarly, if such an event occurs during a transmitted pulse (and is of the worst-case polarity), it reduces the received pulse from >1.0 V to 0.75 V, which is still well above the 0.5 V sensing threshold of the decoder. The preceding magnetic flux density values correspond to specific current magnitudes at given distances from the ADM2682E/ADM2687E transformers. Figure 34 expresses these allowable current magnitudes as a function of frequency for selected distances. As shown in Figure 34, the ADM2682E/ ADM2687E are extremely immune and can be affected only by extremely large currents operated at high frequency very close to the component. For the 1 MHz example, a 0.5 kA current must be placed 5 mm away from the ADM2682E/ADM2687E to affect component operation.
1k
MAXIMUM ALLOWABLE CURRENT (kA)
DISTANCE = 1m 100
10 DISTANCE = 100mm 1 DISTANCE = 5mm 0.1
0.01 MAGNETIC FIELD FREQUENCY (Hz)
08111-020
1k
10k
100k
1M
10M
100M
Figure 34. Maximum Allowable Current for Various Current-toADM2682E/ADM2687E Spacings
Note that in combinations of strong magnetic field and high frequency, any loops formed by printed circuit board (PCB) traces can induce error voltages sufficiently large to trigger the thresholds of succeeding circuitry. Take care in the layout of such traces to avoid this possibility.
Rev. PrE | Page 16 of 20
08111-019
0.001 1k
Preliminary Technical Data APPLICATIONS INFORMATION
PCB LAYOUT
The ADM2682E/ADM2687E isolated RS-422/RS-485 transceiver contains an isoPower integrated dc-to-dc converter, requiring no external interface circuitry for the logic interfaces. Power supply bypassing is required at the input and output supply pins (see Figure 35). The power supply section of the ADM2682E/ ADM2687E uses an 180 MHz oscillator frequency to pass power efficiently through its chip-scale transformers. In addition, the normal operation of the data section of the iCoupler introduces switching transients on the power supply pins. Bypass capacitors are required for several operating frequencies. Noise suppression requires a low inductance, high frequency capacitor, whereas ripple suppression and proper regulation require a large value capacitor. These capacitors are connected between Pin 1 (GND1) and Pin 2 (VCC) and Pin 7 (VCC) and Pin 8 (GND1) for VCC. The VISOIN and VISOOUT capacitors are connected between Pin 9 (GND2) and Pin 10 (VISOOUT) and Pin 15 (VISOIN) and Pin 16 (GND2). To suppress noise and reduce ripple, a parallel combination of at least two capacitors is required with the smaller of the two capacitors located closest to the device. The recommended capacitor values are 0.1 F and 10 F for VISOOUT at Pin 9 and 10 and VCC at Pin 7 and 8. Capacitor values of 0.01 F and 0.1 F are recommended for VISOIN at Pin 15 and 16 and VCC at Pin 1 and 2. The recommended best practice is to use a very low inductance ceramic capacitor, or its equivalent, for the smaller value capacitors. The total lead length between both ends of the capacitor and the input power supply pin should not exceed 10 mm.
10nF 100nF GND1 VCC RxD RE DE TxD VCC GND1 10F 100nF
1 2 3 4 5 6 7 8 16 15 14
ADM2682E/ADM2687E
devices are used at high ambient temperatures, provide a thermal path from the GND pins to the PCB ground plane. The board layout in Figure 35 shows enlarged pads for Pin 1, Pin 8, Pin 9, and Pin 16. Implement multiple vias from the pad to the ground plane to reduce the temperature inside the chip significantly. The dimensions of the expanded pads are at the discretion of the designer and dependent on the available board space.
EMI CONSIDERATIONS
The dc-to-dc converter section of the ADM2682E/ADM2687E components must, of necessity, operate at very high frequency to allow efficient power transfer through the small transformers. This creates high frequency currents that can propagate in circuit board ground and power planes, causing edge and dipole radiation. Grounded enclosures are recommended for applications that use these devices. If grounded enclosures are not possible, good RF design practices should be followed in the layout of the PCB. See Application Note AN-0971, Control of Radiated Emissions with isoPower Devices, for more information.
INSULATION LIFETIME
All insulation structures eventually break down when subjected to voltage stress over a sufficiently long period. The rate of insulation degradation is dependent on the characteristics of the voltage waveform applied across the insulation. Analog Devices conducts an extensive set of evaluations to determine the lifetime of the insulation structure within the ADM2682E/ADM2687E. Accelerated life testing is performed using voltage levels higher than the rated continuous working voltage. Acceleration factors for several operating conditions are determined, allowing calculation of the time to failure at the working voltage of interest. The values shown in Table 9 summarize the peak voltages for 50 years of service life in several operating conditions. In many cases, the working voltage approved by agency testing is higher than the 50-year service life voltage. Operation at working voltages higher than the service life voltage listed leads to premature insulation failure. The insulation lifetime of the ADM2682E/ADM2687E depends on the voltage waveform type imposed across the isolation barrier. The iCoupler insulation structure degrades at different rates, depending on whether the waveform is bipolar ac, unipolar ac, or dc. Figure 36, Figure 37, and Figure 38 illustrate these different isolation voltage waveforms. Bipolar ac voltage is the most stringent environment. A 50-year operating lifetime under the bipolar ac condition determines the Analog Devices recommended maximum working voltage. In the case of unipolar ac or dc voltage, the stress on the insulation is significantly lower. This allows operation at higher working voltages while still achieving a 50-year service life. The working
10nF 100nF GND2 VISOIN A B Z Y VISOOUT GND2 10F 100nF
ADM2682E ADM2687E
13 12 11 10 9
Figure 35. Recommended PCB Layout
In applications involving high common-mode transients, ensure that board coupling across the isolation barrier is minimized. Furthermore, design the board layout such that any coupling that does occur equally affects all pins on a given component side. Failure to ensure this can cause voltage differentials between pins exceeding the absolute maximum ratings for the device, thereby leading to latch-up and/or permanent damage. The ADM2682E/ADM2687E dissipate approximately 650 mW of power when fully loaded. Because it is not possible to apply a heat sink to an isolation device, the devices primarily depend on heat dissipation into the PCB through the GND pins. If the
Rev. PrE | Page 17 of 20
ADM2682E/ADM2687E
voltages listed in Table 9 can be applied while maintaining the 50-year minimum lifetime, provided the voltage conforms to either the unipolar ac or dc voltage cases. Any crossinsulation voltage waveform that does not conform to Figure 37 or Figure 38 should be treated as a bipolar ac waveform, and its peak voltage should be limited to the 50-year lifetime voltage value listed in Table 9.
RATED PEAK VOLTAGE 0V
08111-021
Preliminary Technical Data
TYPICAL APPLICATIONS
An example application of the ADM2682E/ADM2687E for a full-duplex RS-485 node is shown in the circuit diagram of Figure 39. Refer to the section PCB Layout for the recommended placement of the capacitors shown in this circuit diagram. Note that resistors RT are only included at the nodes on either end of the bus and depend on the network configuration. Figure 40 and Figure 41 show typical applications of the ADM2682E/ ADM2687E in half duplex and full duplex RS-485 network configurations. Up to 256 transceivers can be connected to the RS-485 bus. To minimize reflections, terminate the line at the receiving end in its characteristic impedance, and keep stub lengths off the main line as short as possible. For half-duplex operation, this means that both ends of the line must be terminated because either end can be the receiving end.
Figure 36. Bipolar AC Waveform
RATED PEAK VOLTAGE
08111-023
0V
Figure 37. DC Waveform
RATED PEAK VOLTAGE
Figure 38. Unipolar AC Waveform
3.3V/5V POWER SUPPLY
100nF
10F
100nF
10nF 100nF 10F
VCC VCC isoPower DC-TO-DC CONVERTER OSCILLATOR RECTIFIER
08111-022
0V NOTES 1. THE VOLTAGE IS SHOWN AS SINUSODIAL FOR ILLUSTRATION PURPOSES ONLY. IT IS MEANT TO REPRESENT ANY VOLTAGE WAVEFORM VARYING BETWEEN 0 AND SOME LIMITING VALUE. THE LIMITING VALUE CAN BE POSITIVE OR NEGATIVE, BUT THE VOLTAGE CANNOT CROSS 0V.
VISOOUT
VISOIN REGULATOR 100nF 10nF
DIGITAL ISOLATION iCoupler TxD ENCODE DECODE
TRANSCEIVER D
Y Z
MICROCONTROLLER AND UART
DE
ENCODE
DECODE A
RxD DECODE ENCODE R B
RT
RE GND1
ADM2682E/ADM2687E
ISOLATION BARRIER GND2
GND1
Figure 39. Example Circuit Diagram Using the ADM2682E/ADM2687E
Rev. PrE | Page 18 of 20
Preliminary Technical Data
MAXIMUM NUMBER OF TRANSCEIVERS ON BUS = 256
ADM2682E/ADM2687E
ADM2682E/ ADM2687E
RxD RE
A B
RT
A B RT Z Y A B Z Y A B Z Y
ADM2682E/ ADM2687E
R
RxD RE
R
DE TxD
Z D Y
DE
D
TxD
R
R D
ADM2682E/ ADM2687E
RxD RE
ADM2682E/ ADM2687E
RxD RE
D
DE TxD
DE TxD
NOTES 1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE. 2. ISOLATION NOT SHOWN.
Figure 40. ADM2682E/ADM2687E Typical Half Duplex RS-485 Network
MASTER
MAXIMUM NUMBER OF NODES = 256
A Y
SLAVE
RxD RE DE TxD
R B Z D Y
RT
D Z
TxD DE
B
RE
RT
A
R
RxD
ADM2682E/ ADM2687E
A
SLAVE
ADM2682E/ ADM2687E
B Z Y A B Z Y
SLAVE
R D
R D
ADM2682E/ ADM2687E
RxD RE DE TxD RxD RE DE TxD
ADM2682E/ ADM2687E
NOTES 1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE. 2. ISOLATION NOT SHOWN.
Figure 41. ADM2682E/ADM2687E Typical Full Duplex RS-485 Network
Rev. PrE | Page 19 of 20
ADM2682E/ADM2687E OUTLINE DIMENSIONS
13.00 (0.5118) 12.60 (0.4961)
Preliminary Technical Data
16
9
7.60 (0.2992) 7.40 (0.2913)
1 8
10.65 (0.4193) 10.00 (0.3937)
0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10
2.65 (0.1043) 2.35 (0.0925)
0.75 (0.0295) 45 0.25 (0.0098)
8 0 1.27 (0.0500) 0.40 (0.0157)
1.27 (0.0500) BSC
0.51 (0.0201) 0.31 (0.0122)
SEATING PLANE 0.33 (0.0130) 0.20 (0.0079)
COMPLIANT TO JEDEC STANDARDS MS-013-AC CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 42. 16-Lead Standard Small Outline Package with Increased Creepage [SOIC_IC] Wide Body, (RI-16) Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model 1 ADM2682EBRIZ ADM2682EBRIZ-RL7 ADM2687EBRIZ ADM2687EBRIZ-RL7
1
Data Rate (Mbps) 16 16 0.5 0.5
Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Description 16-Lead SOIC_IC 16-Lead SOIC_IC 16-Lead SOIC_IC 16-Lead SOIC_IC
Package Option RI-16 RI-16 RI-16 RI-16
Z = RoHS Compliant Part.
(c)2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR09927-0-5/11(PrE)
Rev. PrE | Page 20 of 20
10-12-2010-A

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