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Preliminary Technical Data
FEATURES
High Speed ESD Protected Full-Duplex iCoupler(R) Isolated RS-485 Transceiver ADM2490E
FUNCTIONAL BLOCK DIAGRAM
Isolated Full Duplex RS-485/RS-422 transceiver 8kV ESD protection on RS-485 I/O pins 16Mbps Data Rate Complies with ANSI TIA/EIA RS-485-A-1998 and ISO 8482:1987(E) Suitable for 5 V or 3 V operation (VDD1) High common mode transient immunity: >25kV/ s Receiver open-circuit fail-safe design Thermal shutdown protection Safety and regulatory approvals pending UL recognition: 2500 V rms for 1 minute per UL 1577 CSA component acceptance notice #5A VDE certificate of conformity DIN EN 60747-5-2 (VDE 0884 Part 2):2003-01 DIN EN 60950 (VDE 0805):2001-12;EN 60950:2000 VIORM = 560 V peak Operating Temperature Range: -40 to 105C Wide body 16-lead SOIC package
Figure 1. Functional Block Diagram
GENERAL DESCRIPTION
The ADM2490E is an isolated data transceiver with 8kV ESD protection suitable for high-speed full-duplex communication on multipoint transmission lines. It is designed for balanced transmission lines and complies with ANSI TIA/EIA RS-485-A and ISO 8482:1987(E). The device employs Analog Devices' iCoupler technology to combine a 2-channel isolator, a 3-state differential line driver and a differential input receiver into a single package. The differential transmitter outputs and receiver inputs feature electrostatic discharge circuitry which provides protection to 8kV using the Human Body Model (HBM). The logic side of the device can be powered with either a 5 V or a 3 V supply while an isolated 5V supply is required for the bus side. The device has current-limiting and thermal shutdown features to protect against output short circuits and situations where bus contention might cause excessive power dissipation.
APPLICATIONS
Isolated RS-485/RS-422 Interfaces Industrial field networks INTERBUS Multipoint data transmission systems
Rev. PrI
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2005 Analog Devices, Inc. All rights reserved.
ADM2490E ADM2490E--SPECIFICATIONS
Preliminary Technical Data
Table 1. All voltages are relative to their respective ground; 2.7 VDD1 5.5 V, 4.5 V VDD2 5.5 V. All min/max specifications apply over the entire recommended operation range unless otherwise noted. All typical specifications are at TA = 25C, VDD1=VDD2=5.0 V unless otherwise noted.
Parameter SUPPLY CURRENT Power Supply Current Logic Side TxD/RxD Data Rate < 2 Mbps Bus Side Power Supply Current Bus Side DRIVER Differential Outputs Differential Output Voltage, Loaded Symbol Min Typ Max Unit Test Conditions
IDD1 IDD2
3.0 4.0
mA mA
2.7VVDD15.5V Unloaded
|VOD2| |VOD4| |VOD| VOC |VOC| IOS VILTxD VIHTRxD ITxD
2.0 1.5 1.5
|VOD| for Complementary Output States Common Mode Output Voltage |VOC| for Complementary Output States Short Circuit Output Current Logic Inputs Input Threshold Low Input Threshold High TxD 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
5.0 5.0 5.0 0.2 3.0 0.2 200
V V V V V V mA V V A
R=50, (RS-422), Fig. 3 R = 27 (RS-485), Fig 3 -7VVtest112V, Fig. 4 RL=54 or 100, Fig. 3 RL=54 or 100, Fig. 3 RL=54 or 100, Fig. 3
0.25VDD1 -10 0.01 0.7VDD1 10
VTH VHYS II RIN VOLRxD VOHRxD
-0.2 70
0.2 1.0
-0.8 12 0.0 VDD1-0.2 0.4
V mV mA mA k V V
VOC=0V VOC=12V VOC=-7V
VDD1 - 0.3
IORxD=4mA, VA-VB=-0.2V IORxD=-1.5 mA, VA-VB=0.2V
Rev. PrI | Page 2 of 13
Preliminary Technical Data TIMING SPECIFICATIONS (T
Parameter DRIVER Maximum Data Rate Propagation Delay Pulse Width Distortion, PWD=|tPYLH-tPYHL|, PWD=|tPZLH-tPZHL| Single Ended Output Rise/Fall Time RECEIVER Propagation Delay Pulse Width Distortion, PWD=|tPLH-tPHL|,
ADM2490E
A
= -40C to +85C)
Symbol Min. 16 tPLH, tPHL tPWD, tPWD tR, tF tPLH, tPHL, tPWD, 45 60 7 20 60 10 Typ Max Unit Mbps ns ns ns ns ns Test Conditions
RL=54, CL1=C L2=100pF, Fig. 5 RL=54, CL1=C L2=100pF, Fig. 5 RL=54, CL1=C L2=100pF, Fig. 5 CL=15pF, Fig. 6 CL=15pF, Fig. 6
TIMING SPECIFICATIONS (T
Parameter DRIVER Maximum Data Rate Propagation Delay Pulse Width Distortion, PWD=|tPYLH-tPYHL|, PWD=|tPZLH-tPZHL| Single Ended Output Rise/Fall Time RECEIVER Propagation Delay Pulse Width Distortion, PWD=|tPLH-tPHL|,
A
= -40C to +105C)
Symbol Min. 10 tPYLH, tPYHL, tPZLH, tPZHL tPWD, tPWD tR, tF tPLH, tPHL, tPWD, 45 60 9 35 60 10 Typ Max Unit Mbps ns ns ns ns ns Test Conditions
RL=54, CL1=C L2=100pF, Fig. 5 RL=54, CL1=C L2=100pF, Fig. 5 RL=54, CL1=C L2=100pF, Fig. 5 CL=15pF, Fig. 6 CL=15pF, Fig. 6
ABSOLUTE MAXIMUM RATINGS
Table 2. Ambient temperature = 25 C unless otherwise noted. All voltages are relative to their respective ground.
Parameter Storage temperature Ambient operating temperature VDD1 VDD2 Logic input voltages Bus terminal voltages Logic output voltages Average output current, per pin ESD (human body model) on A,B,Y and Z pins JA Thermal Impedance Rating -55C to 150C -40C to 105C -0.5 V to +7 V -0.5 V to +6 V -0.5V to VDD1 + 0.5V -9V to 14V -0.5V to VDD1 + 0.5V 35mA 8kV 73C/W
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 listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Absolute maximum ratings apply individually only, not in combination.
Rev. PrI | Page 3 of 13
ADM2490E ADM2490E CHARACTERISTICS
PACKAGE CHARACTERISTICS
Table 3.
Parameter Resistance (Input-Output)1 Capacitance (Input-Output)1 Input Capacitance2 Input IC Junction-to-Case Thermal Resistance Output IC Junction-to-Case Thermal Resistance
1 2
Preliminary Technical Data
Symbol RI-O CI-O CI JCI JCO
Min
Typ 1012 3 4 33 28
Max
Unit pF pF C/W C/W
Test Conditions f = 1 MHz Thermocouple located at center of package underside
Device considered a two-terminal device: Pins 1, 2, 3, 4, 5, 6, 7, and 8 shorted together, and Pins 9, 10, 11, 12, 13, 14, 15, and 16 shorted together. Input capacitance is from any input data pin to ground.
REGULATORY INFORMATION
The ADM2490E is to be approved by the following organizations: Table 4.
Organization UL Approval Type To be recognized under 1577 component recognition program. Notes In accordance with UL1577, each ADM2490E is proof-tested by applying an insulation test voltage 3000 V rms for 1 second (current leakage detection limit = 5 A). In accordance with VDE 0884, each ADM2490E is proof-tested by applying an insulation test voltage 1050 VPEAK for 1 second (partial discharge detection limit = 5 pC).
CSA VDE
To be approved under CSA Component Acceptance Notice #5A. To be certified according to DIN EN 60747-5-2 (VDE 0884 Part 2): 2003-01
INSULATION AND SAFETY-RELATED SPECIFICATIONS
Table 5.
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 2500 7.45 min 8.1 min 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 Part 1. Material Group (DIN VDE 0110, 1/89,).
CTI
Rev. PrI | Page 4 of 13
Preliminary Technical Data
VDE 0884 INSULATION CHARACTERISTICS
ADM2490E
This isolator is suitable for basic electrical isolation only within the safety limit data. Maintenance of the safety data must be ensured by means of protective circuits. An asterisk (*) on packages denotes VDE 0884 approval for 560 V peak working voltage. Table 6.
Description Installation classification per DIN VDE 0110 for rated mains voltage 150 V rms 300 V rms 400 V rms Climatic classification Pollution degree (DIN VDE 0110, Table 1) Maximum working insulation voltage Input to output test voltage, Method b1 VIORM x 1.875 = VPR, 100% production tested, tm = 1 sec, partial discharge < 5 pC Input to output test voltage, Method a (After environmental tests, Subgroup 1) VIORM x 1.6 = VPR, tm = 60 sec, partial discharge < 5 pC (After input and/or safety test, Subgroup 2/3) VIORM x 1.2 = VPR, tm = 60 sec, partial discharge < 5 pC Highest allowable overvoltage (Transient overvoltage, tTR = 10 sec) Safety-limiting values (maximum value allowed in the event of a failure. See thermal derating curve) Case temperature Input current Output current Insulation resistance at Ts, VIO = 500 V Symbol Characteristic I to IV I to III I to II 40/85/21 2 560 1050 Unit
VIORM VPR
VPEAK VPEAK
896 VPR VTR 672 4000
VPEAK VPEAK VPEAK
TS IS, INPUT IS, OUTPUT Rs
150 265 335 >109
C mA mA
Rev. PrI | Page 5 of 13
ADM2490E PIN CONFIGURATION AND FUNCTIONAL DESCRIPTIONS
VDD1 1 GND1 2 RxD 3 NC 4 GND1 5 TxD 6 NC 7 GND1 8
16 VDD2 15 GND2
Preliminary Technical Data
ADM2490E
T OP V IEW
( Not t o Scale)
14 A 13 B 12 NC 11 Z 10 Y 9
GND2
Figure 2. ADM2490E Pin Out
Table 7.Preliminary Pin Function Description
Pin(s) 1 2,5,8 3 4,7,12 6 9,15 16 9, 15 11 10 13 14 Mnemonic VDD1 GND1 RxD NC TxD GND2 VDD2 GND2 Z Y B A Function Power supply, logic side. Decoupling capacitor to GND1 required, capacitor value should be between 0.01 F and 0.1 F. Ground, logic side Receiver output. No Connect, pins must be left floating Transmit data Ground, bus side Power supply, bus side. Decoupling capacitor to GND2 required, capacitor value should be between 0.01 F and 0.1 F. Ground, bus side Driver Inverting Output Driver Non-inverting Output Receiver Inverting Input Receiver Non-inverting Input
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. PrI | Page 6 of 13
Preliminary Technical Data TEST CIRCUITS
R VOD R VOC
A Y RLDIFF CL1
ADM2490E
Z B
CL2
Figure 3. Driver Voltage Measurement
Figure 5. Driver Propagation Delay
375
A
VOD3 60 375 VTST
B
4CL
VOUT
Figure 4. Driver Voltage Measurement
Figure 6. Receiver Propagation Delay
SWITCHING CHARACTERISTICS
A, B
0V
0V
t PLH
t PHL VOH
RO
1.5V
1.5V
VOL
Figure 7. Driver Propagation Delay, Rise/Fall Timing
Figure 8. Receiver Propagation Delay
Rev. PrI | Page 7 of 13
ADM2490E TYPICAL PERFORMANCE CHARACTERISTICS
Preliminary Technical Data
Figure 3. Unloaded Supply Current vs. Temperature
Figure 6. Driver/Receiver Propagation Delay, Low to High (RLDiff = 54 , CL1 = CL2 = 100 pF)
Figure 4. Driver Propagation Delay vs. Temperature
Figure 7. Driver/Receiver Propagation Delay, High to Low (RLDiff = 54 , CL1 = CL2 = 100 pF)
Figure 5. Receiver Propagation Delay vs. Temperature
Figure 8. Thermal Derating Curve, Dependence of Safety-Limiting Values with Case Temperature per VDE 0884
Rev. PrI | Page 8 of 13
Preliminary Technical Data
ADM2490E
Figure 9. Output Current vs. Receiver Output High Voltage
Figure 12. Receiver Output Low Voltage vs. Temperature IRxD = -4 mA
Figure 10. Output Current vs. Receiver Output Low Voltage
Figure 11. Receiver Output High Voltage vs. Temperature IRxD = -4 mA
Rev. PrI | Page 9 of 13
ADM2490E CIRCUIT DESCRIPTION
ELECTRICAL ISOLATION
In the ADM2490, electrical isolation is implemented on the logic side of the interface. Therefore, the part has two main sections: a digital isolation section and a transceiver section (see Figure 9). Driver input signal, applied to the TxD pin, 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 receiver output, referenced to isolated ground in the transceiver section, is coupled across the isolation barrier to appear at the RxD pin referenced to logic ground.
Preliminary Technical Data
TRUTH TABLES
The truth tables in this section use these abbreviations:
Letter H I L X Z NC Description High level Indeterminate Low level Irrelevant High impedance (off) Disconnected
iCoupler Technology
The digital signals are transmitted 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 then decoded into the binary value that was originally transmitted.
V DD1 ISOLATION BARRIER Y TxD ENCODE DECODE D Z A RxD DECODE ENCODE R B V DD2
Table 8. Transmitting
Supply Status VDD1 VDD2 On On On On Inputs TxD H L Output Y Z H L L H
Table 9. Receiving
Supply Status VDD1 VDD2 On On On On On On On On On Off Off On Off Off Inputs A-B (V) >0.2 <-0.2 -0.2 < A - B < 0.2 Inputs open X X X Output RxD H L I H H H L
DIGITAL ISOLATION
TRANSCEIVER
GND 1
GND 2
Figure 9. ADM2490E Digital Isolation and Transceiver Sections
Rev. PrI | Page 10 of 13
Preliminary Technical Data
THERMAL SHUTDOWN
MAXIMUM ALLOWABLE MAGNETIC FLUX DENSITY (kGAUSS) 100
ADM2490E
The ADM2490E contains thermal shutdown circuitry that protects the part 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 re-enabled at a temperature of 140C.
10
1
0.1
0.01
The receiver input includes a fail-safe feature that guarantees a logic high on the RxD pin when the A and B inputs are floating or open-circuited.
10k 100k 1M 10M MAGNETIC FIELD FREQUENCY (Hz)
100M
Figure10. Maximum Allowable External Magnetic Flux Density
MAGNETIC FIELD IMMUNITY
Because iCouplers use a coreless technology, no magnetic components are present, and the problem of magnetic saturation of the core material does not exist. Therefore, iCouplers have essentially infinite dc field immunity. The analysis below defines the conditions under which this may occur. The ADM2409E's 3 V operating condition is examined because it represents the most susceptible mode of operation. The limitation on the iCoupler's ac magnetic field immunity is set by the condition in which the induced error voltage in the receiving coil (the bottom coil in this case) is made sufficiently large, either to falsely set or reset the decoder. The voltage induced across the bottom coil is given by
- d 2 V = rn ; n = 1, 2, . . . , N dt
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 the worst-case polarity, it reduces the received pulse from >1.0 V to 0.75 V--still well above the 0.5 V sensing threshold of the decoder. Figure 11 shows the magnetic flux density values in terms of more familiar quantities such as maximum allowable current flow at given distances away from the ADM2490E transformers.
1000 DISTANCE = 1m 100 DISTANCE = 5mm 10
10k 100k 1M 10M MAGNETIC FIELD FREQUENCY (Hz)
100M
Figure11. Maximum Allowable Current for Various Current-to-ADM2490E Spacings
At combinations of strong magnetic field and high frequency, any loops formed by printed circuit board traces could induce sufficiently large error voltages to trigger the thresholds of succeeding circuitry. Care should be taken in the layout of such traces to avoid this possibility.
Rev. PrI | Page 11 of 13
04604-017
where, if the pulses at the transformer output are greater than 1.0 V in amplitude: = magnetic flux density (gauss) N = number of turns in receiving coil rn = radius of nth turn in receiving coil (cm) The decoder has a sensing threshold of about 0.5 V; therefore, there is a 0.5 V margin in which induced voltages can be tolerated. Given the geometry of the receiving coil and an imposed requirement that the induced voltage is, at most, 50% of the 0.5 V margin at the decoder, a maximum allowable magnetic field is calculated, as shown in Figure 10.
MAXIMUM ALLOWABLE CURRENT (kA)
DISTANCE = 100mm 1
0.1
0.01 1k
04604-016
RECEIVER FAIL-SAFE INPUTS
0.001 1k
ADM2490E APPLICATIONS INFORMATION
ISOLATED POWER SUPPLY CIRCUIT
The ADM2490E requires isolated power capable of 5 V at 100 mA to be supplied between the VDD2 and the GND2 pins. A transformer driver circuit with a center-tapped transformer and LDO can be used to generate the isolated 5V supply as shown in figure 12 below. The center-tapped transformer provides electrical isolation of the 5V isolated power supply. The primary winding of the transformer is excited with a pair of square waveforms that are 180 out of phase with each other. A pair of Schottky diodes and a smoothing capacitor are used to create a rectified signal from the secondary winding. The ADP667 linear voltage regulator provides a regulated power supply to the ADM2490E's bus-side circuitry (VDD2).
ISOLATION BARRIER Vcc SD103C IN OUT V CC 22F +5V 10F
Preliminary Technical Data
PC BOARD LAYOUT
The ADM2490E isolated RS-485 transceiver requires no external interface circuitry for the logic interfaces. Power supply bypassing is strongly recommended at the input and output supply pins (Figure 13). Bypass capacitors are most conveniently connected between Pins 1 and 2 for VDD1 and between Pins 15 and 16 for VDD2. The capacitor value should be between 0.01 F and 0.1 F. The total lead length between both ends of the capacitor and the input power supply pin should not exceed 20 mm. Bypass-ing between Pins 1 and 8 and between Pins 9 and 16 should also be considered unless the ground pair on each package side is connected close to the package.
VDD1 GND1 RxD NC GND1 TxD NC GND1 VDD2 GND2 A B NC Z Y GND2
ADM2490E
Transformer Driver
ADP667
SET GND SHDN
78253
SD103C
NC = NO CONNECT
VCC V DD1 V DD2
Figure13. Recommended Printed Circuit Board Layout In applications involving high common-mode transients, care should be taken to ensure that board coupling across the isolation barrier is minimized. Furthermore, the board layout should be designed such that any coupling that does occur equally affects all pins on a given component side. Failure to ensure this could cause voltage differentials between pins exceeding the device's Absolute Maximum Ratings, thereby leading to latch-up or permanent damage.
ADM2490E
GND 1 GND 2
Figure 12. Isolated Power Supply Circuit
Rev. PrI | Page 12 of 13
Product Concept Document OUTLINE DIMENSIONS
0.413 (10.50)
16 9
ADM2490E
0.299 (7.60)
1 8
0.419 (10.65)
PIN 1 0.012 (0.3) 0.05 (1.27) BSC 0.019 (0.49) 0.014 (2.65) SEATING PLANE
0.030 (0.75)
0.013 (0.32)
0.042 (1.07)
Figure 14. 16-Lead Wide-Body Small Outline Package [SOIC] (RW-16) Dimensions shown in millimeters
ORDERING GUIDE
Model ADM2490EWRWZ1 ADM2490EWRWZ-REEL71 Temperature Range -40C to +105C -40C to +105C Package Description 16-Lead Wide Body SOIC 16-Lead Wide Body SOIC Package Option RW-16 RW-16
1
Z = Pb-free part.
(c) 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.
PR05889-0-1/06(PrI)
Rev. PrI | Page 13 of 13

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