5 kV rms Signal and Power Isolated RS-485 Transceiver with 15 kV ESD ADM2682E/ADM2687E FEATURES FUNCTIONAL BLOCK DIAGRAM VCC VISOOUT isoPower DC-TO-DC CONVERTER OSCILLATOR RECTIFIER VISOIN REGULATOR TRANSCEIVER DIGITAL ISOLATION iCoupler Y TxD ENCODE DECODE D Z DE ENCODE DECODE RxD DECODE ENCODE A R B ADM2682E/ADM2687E RE GND1 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 that 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(R) dc-to-dc 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. The ADM2682E/ADM2687E drivers have 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 AN-0971 Application Note, Recommendations for Control of Radiated Emissions with isoPower Devices, for details on board layout considerations. Rev. 0 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: 781.461.3113 (c)2011 Analog Devices, Inc. All rights reserved. 09927-001 5 kV rms isolated RS-485/RS-422 transceiver, configurable as half or full duplex isoPower 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 ADM2682E/ADM2687E TABLE OF CONTENTS Features .............................................................................................. 1 Switching Characteristics .............................................................. 15 Applications....................................................................................... 1 Circuit Description......................................................................... 16 Functional Block Diagram .............................................................. 1 Signal Isolation ........................................................................... 16 General Description ......................................................................... 1 Power Isolation ........................................................................... 16 Revision History ............................................................................... 2 Truth Tables................................................................................. 16 Specifications..................................................................................... 3 Thermal Shutdown .................................................................... 16 ADM2682E Timing Specifications ............................................ 4 Open- and Short-Circuit, Fail-Safe Receiver Inputs.............. 16 ADM2687E Timing Specifications ............................................ 4 DC Correctness and Magnetic Field Immunity........................... 16 Package Characteristics ............................................................... 4 Applications Information .............................................................. 18 Regulatory Information............................................................... 5 PCB Layout ................................................................................. 18 Insulation and Safety-Related Specifications............................ 5 EMI Considerations................................................................... 18 VDE 0884 Insulation Characteristics (Pending)...................... 6 Insulation Lifetime ..................................................................... 19 Absolute Maximum Ratings............................................................ 7 Isolated Supply Considerations ................................................ 19 ESD Caution.................................................................................. 7 Typical Applications................................................................... 20 Pin Configuration and Function Descriptions............................. 8 Outline Dimensions ....................................................................... 22 Typical Performance Characteristics ............................................. 9 Ordering Guide .......................................................................... 22 Test Circuits..................................................................................... 14 REVISION HISTORY 7/11--Revision 0: Initial Version Rev. 0 | Page 2 of 24 ADM2682E/ADM2687E SPECIFICATIONS 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 ADM2682E SUPPLY CURRENT Data Rate = 16 Mbps ICC Min Typ |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 Unit Test Conditions/Comments 140 mA mA mA mA mA 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 175 260 130 200 mA mA mA mA V 120 load between Y and Z 54 load between Y and Z 120 load between Y and Z 54 load between Y and Z 3.6 3.6 3.6 0.2 3.0 0.2 200 30 V V V V V V mA A RL = 100 (RS-422), see Figure 29 RL = 54 (RS-485), see Figure 29 -7 V VTEST1 12 V, see Figure 30 RL = 54 or 100 , see Figure 29 RL = 54 or 100 , see Figure 29 RL = 54 or 100 , see Figure 29 90 72 125 98 Data Rate = 16 Mbps, 4.5 VCC 5.5 V ISOLATED SUPPLY VOLTAGE DRIVER Differential Outputs Differential Output Voltage, Loaded Max VISOOUT |VOD2| |VOD3| |VOD| VOC |VOC| IOS IO 3.3 2.0 1.5 1.5 DE = 0 V, RE = 0 V, VCC = 0 V or 3.6 V, VIN = 12 V DE = 0 V, RE = 0 V, VCC = 0 V or 3.6 V, VIN = -7 V -30 A VIL VIH II 0.27 VCC -10 0.01 V V A DE, RE, TxD DE, RE, TxD DE, RE, TxD VTH VHYS II -200 -125 15 mV mV A A k -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 V V mA kV/s IO = 1.5 mA, VA - VB = -0.2 V IO = -1.5 mA, VA - VB = 0.2 V 0.7 VCC 10 -30 125 RIN -100 96 VOL VOH VCC - 0.3 0.2 VCC - 0.2 0.4 100 25 VCM = 1 kV, transient magnitude = 800 V 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. 0 | Page 3 of 24 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 Symbol Min Typ Max Unit Test Conditions/Comments tDPLH tDPHL tSKEW tDR, tDF tZL, tZH tLZ, tHZ 63 64 1 100 100 8 15 120 150 Mbps ns ns ns ns ns ns RL = 54 , CL1 = C L2 = 100 pF, see Figure 31 and Figure 35 RL = 54 , CL1 = C L2 = 100 pF, see Figure 31 and Figure 35 RL = 54 , CL1 = CL2 = 100 pF, see Figure 31 and Figure 35 RL = 54 , CL1 = CL2 = 100 pF, see Figure 31 and Figure 35 RL = 110 , CL = 50 pF, see Figure 32 and Figure 37 RL = 110 , CL = 50 pF, see Figure 32 and Figure 37 tRPLH tRPHL tSKEW tZL, tZH tLZ, tHZ 94 95 1 110 110 12 15 15 ns ns ns ns ns CL = 15 pF, see Figure 33 and Figure 36 CL = 15 pF, see Figure 33 and Figure 36 CL = 15 pF, see Figure 33 and Figure 36 RL = 1 k, CL = 15 pF, see Figure 34 and Figure 38 RL = 1 k, CL = 15 pF, see Figure 34 and Figure 38 Typ Max Unit Test Conditions/Comments 503 510 7 700 700 100 1100 2.5 200 kbps ns ns ns ns s ns RL = 54 , CL1 = C L2 = 100 pF, see Figure 31 and Figure 35 RL = 54 , CL1 = C L2 = 100 pF, see Figure 31 and Figure 35 RL = 54 , CL1 = CL2 = 100 pF, see Figure 31 and Figure 35 RL = 54 , CL1 = CL2 = 100 pF, see Figure 31 and Figure 35 RL = 110 , CL = 50 pF, see Figure 32 and Figure 37 RL = 110 , CL = 50 pF, see Figure 32 and Figure 37 91 95 4 200 200 30 15 15 ns ns ns ns ns CL = 15 pF, see Figure 33 and Figure 36 CL = 15 pF, see Figure 33 and Figure 36 CL = 15 pF, see Figure 33 and Figure 36 RL = 1 k, CL = 15 pF, see Figure 34 and Figure 38 RL = 1 k, CL = 15 pF, see Figure 34 and Figure 38 Typ 1012 3 4 Max 16 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 tDPLH tDPHL tSKEW tDR, tDF tZL, tZH tLZ, tHZ Min 500 250 250 200 tRPLH tRPHL tSKEW tZL, tZH tLZ, tHZ 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 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. 0 | Page 4 of 24 Unit pF pF Test Conditions/Comments f = 1 MHz ADM2682E/ADM2687E REGULATORY INFORMATION Table 5. ADM2682E/ADM2687E Approvals (Pending) Organization UL (Pending) CSA (Pending) VDE (Pending) 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 60950-1-07 and IEC 60950-1, 380 V rms (537 V peak) maximum working voltage. Basic insulation per CSA 60950-1-07 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 Part 2):2003-01. In accordance with DIN EN 60747-5-2, each ADM2682E/ADM2687E is proof tested by applying an insulation test voltage 1590 V peak for 1 second. INSULATION AND SAFETY-RELATED SPECIFICATIONS Table 6. Parameter Rated Dielectric Insulation Voltage Minimum External Air Gap (Clearance) Symbol L(I01) Value 5000 >8.0 Unit V rms mm Minimum External Tracking (Creepage) L(I02) >8.0 mm Minimum Internal Gap (Internal Clearance) Tracking Resistance (Comparative Tracking Index) Isolation Group CTI 0.017 min >175 IIIa mm V Rev. 0 | Page 5 of 24 Test Conditions/Comments 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) ADM2682E/ADM2687E VDE 0884 INSULATION CHARACTERISTICS (PENDING) 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. 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 Test Conditions/Comments Symbol Characteristic Unit I to IV I to III I to II 40/85/21 2 Table 1 of DIN VDE 0110 VIORM VPR 846 V peak VIORM x 1.875 = VPR, 100% production tested, tm = 1 sec, partial discharge < 5 pC 1590 V peak VIORM x 1.6 = VPR, tm = 60 sec, partial discharge < 5 pC VIORM x 1.2 = VPR, tm = 60 sec, partial discharge < 5 pC 1375 1018 V peak V peak VTR 6000 V peak TS IS, INPUT IS, OUTPUT RS 150 265 335 >109 C mA mA Transient overvoltage, tTR = 10 sec Maximum value allowed in the event of a failure VIO = 500 V Rev. 0 | Page 6 of 24 ADM2682E/ADM2687E ABSOLUTE MAXIMUM RATINGS TA = 25C, unless otherwise noted. All voltages are relative to their respective ground. Table 8. Parameter VCC Digital Input Voltage (DE, RE, TxD) 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 Table 9. Maximum Continuous Working Voltage1 Parameter AC Voltage Bipolar Waveform Unipolar Waveform Basic Insulation Reinforced Insulation DC Voltage Basic Insulation Reinforced Insulation 1 260C 215C 220C 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. Max Unit Reference Standard 424 V peak All certifications, 50-year minimum lifetime 600 537 V peak V peak 600 537 V peak V peak Maximum approved working voltage per IEC 60950-1 Maximum approved working voltage per IEC 60950-1 Refers to continuous voltage magnitude imposed across the isolation barrier. See the Insulation Lifetime section for more details. ESD CAUTION Rev. 0 | Page 7 of 24 ADM2682E/ADM2687E PIN CONFIGURATION AND FUNCTION DESCRIPTIONS GND1 1 16 GND2 VCC 2 RE 4 DE 5 TxD 6 VCC 7 ADM2682E/ ADM2687E TOP VIEW (Not to Scale) 14 A 13 B 12 Z 11 Y 10 VISOOUT GND1 8 9 GND2 NOTES 1. PIN 10 AND PIN 15 MUST BE CONNECTED EXTERNALLY. 09927-002 RxD 3 15 VISOIN Figure 2. Pin Configuration Table 10. Pin Function Descriptions Pin No. 1 2 Mnemonic GND1 VCC 3 RxD 4 RE 5 6 7 DE TxD VCC 8 9 10 GND1 GND2 VISOOUT 11 12 13 14 15 Y Z B A VISOIN 16 GND2 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, while driving it high disables the receiver. Driver Enable Input. Driving this input high enables the driver, while 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. Rev. 0 | Page 8 of 24 ADM2682E/ADM2687E TYPICAL PERFORMANCE CHARACTERISTICS 200 140 120 160 SUPPLY CURRENT, ICC (mA) RL = 54 140 120 RL = 120 100 80 60 NO LOAD 40 RL = 54 100 80 RL = 120 60 40 -15 10 35 60 85 TEMPERATURE (C) 0 09927-203 0 -40 1 7 10 13 16 DATA RATE (Mbps) Figure 3. ADM2682E Supply Current (ICC) vs. Temperature (Data Rate = 16 Mbps, DE = 3.3 V, VCC = 3.3 V) Figure 6. ADM2682E Supply Current (ICC) vs. Data Rate (TA = 25C, DE = 5 V, VCC = 5 V) 160 120 140 100 RL = 54 120 100 SUPPLY CURRENT, ICC (mA) RL = 120 80 60 NO LOAD 40 RL = 54 80 RL = 120 60 40 NO LOAD 20 20 -15 10 35 60 85 TEMPERATURE (C) 0 -40 09927-204 0 -40 -15 10 35 60 85 TEMPERATURE (C) Figure 4. ADM2682E Supply Current (ICC) vs. Temperature (Data Rate = 16 Mbps, DE = 5 V, VCC = 5 V) 09927-207 SUPPLY CURRENT, ICC (mA) 4 09927-206 20 20 Figure 7. ADM2687E Supply Current (ICC) vs. Temperature (Data Rate = 500 kbps, DE = 5 V, VCC = 5 V) 180 160 160 140 SUPPLY CURRENT, ICC (mA) RL = 54 140 120 RL = 120 100 80 60 40 NO LOAD 20 0 1 4 7 120 RL = 54 100 80 RL = 120 60 40 NO LOAD 20 10 13 DATA RATE (Mbps) 16 09927-205 SUPPLY CURRENT, ICC (mA) NO LOAD Figure 5. ADM2682E Supply Current (ICC) vs. Data Rate (TA = 25C, DE = 3.3 V, VCC = 3.3 V) 0 -40 -15 10 35 60 TEMPERATURE (C) Figure 8. ADM2687E Supply Current (ICC) vs. Temperature (Data Rate = 500 kbps, DE = 3.3 V, VCC = 3.3 V) Rev. 0 | Page 9 of 24 85 09927-208 SUPPLY CURRENT, ICC (mA) 180 ADM2682E/ADM2687E 140 600 RL = 54 580 DRIVER PROPAGATION DELAY (ns) SUPPLY CURRENT, ICC (mA) 120 100 RL = 120 80 60 40 NO LOAD 20 560 540 tDPLH 520 tDPHL 500 480 460 440 200 275 350 425 400 -40 09927-209 125 500 DATA RATE (kbps) Figure 9. ADM2687E Supply Current (ICC) vs. Data Rate (TA = 25C, DE = 3.3 V, VCC = 3.3 V) -15 10 35 TEMPERATURE (C) 60 85 Figure 12. ADM2687E Differential Driver Propagation Delay vs. Temperature 120 RL = 54 TxD 80 RL = 120 1 60 Z 40 Y NO LOAD 20 0 50 125 200 275 350 425 500 DATA RATE (kbps) CH1 2.0V CH3 2.0V Figure 10. ADM2687E Supply Current (ICC) vs. Data Rate (TA = 25C, DE = 5 V, VCC = 5 V) CH2 2.0V M10.00ns A CH1 1.28V 09927-109 3 09927-210 SUPPLY CURRENT, ICC (mA) 100 Figure 13. ADM2682E Driver Propagation Delay 72 DRIVER PROPAGATION DELAY (ns) 70 68 66 64 tDPHL 62 TxD 1 tDPLH 60 58 Z 56 Y 54 3 10 35 TEMPERATURE (C) 60 85 Figure 11. ADM2682E Differential Driver Propagation Delay vs. Temperature Rev. 0 | Page 10 of 24 CH1 2.0V CH3 2.0V CH2 2.0V M200ns A CH1 2.56V Figure 14. ADM2687E Driver Propagation Delay 09927-110 -15 09927-107 52 50 -40 09927-108 420 0 50 ADM2682E/ADM2687E 0.32 0 0.30 OUTPUT LOW VOLTAGE (V) -20 -30 -40 -50 0.26 0.24 0.22 0 1 2 3 OUTPUT HIGH VOLTAGE (V) 4 5 09927-111 -60 -70 0.28 0.20 -40 -15 10 35 TEMPERATURE (C) 60 85 Figure 18. Receiver Output Low Voltage vs. Temperature Figure 15. Receiver Output Current vs. Receiver Output High Voltage 60 B 40 A 1 30 RxD 20 10 3 0 1 2 3 OUTPUT LOW VOLTAGE (V) 4 5 CH1 2.0V CH3 2.0V 09927-112 0 Figure 16. Receiver Output Current vs. Receiver Output Low Voltage CH2 2.0V M10.00ns A CH1 2.56V 09927-115 OUTPUT CURRENT (mA) 50 Figure 19. ADM2682E Receiver Propagation Delay 4.75 A 4.73 4.72 4.71 B 1 4.70 4.69 4.68 4.67 RxD 4.65 -40 -15 10 35 TEMPERATURE (C) 60 85 Figure 17. Receiver Output High Voltage vs. Temperature CH1 2.0V CH3 2.0V CH2 2.0V M10.00ns A CH1 2.56V Figure 20. ADM2687E Receiver Propagation Delay Rev. 0 | Page 11 of 24 09927-116 3 4.66 09927-113 OUTPUT HIGH VOLTAGE (V) 4.74 09927-114 OUTPUT CURRENT (mA) -10 ADM2682E/ADM2687E 3.44 3.43 ISOLATED SUPPLY VOLTAGE (V) 97 96 tRPHL 95 tRPLH 94 93 3.41 3.40 NO LOAD 3.39 3.38 RL = 120 3.37 RL = 54 3.36 10 35 TEMPERATURE (C) 60 85 3.34 -40 -15 10 35 60 85 TEMPERATURE (C) 09927-224 -15 Figure 24. ADM2682E Isolated Supply Voltage vs. Temperature (VCC = 5 V, Data Rate = 16 Mbps) Figure 21. ADM2682E Receiver Propagation Delay vs. Temperature 3.37 100 ISOLATED SUPPLY VOLTAGE (V) 99 98 97 96 tRPHL 95 94 93 92 tRPLH 3.36 3.35 NO LOAD 3.34 RL = 120 3.33 RL = 54 3.32 3.31 90 -40 -15 10 35 TEMPERATURE (C) 60 85 3.30 -40 -15 10 35 60 85 TEMPERATURE (C) 09927-225 91 09927-118 RECEIVER PROPAGATION DELAY (ns) 3.42 3.35 92 -40 09927-117 RECEIVER PROPAGATION DELAY (ns) 98 Figure 25. ADM2687E Isolated Supply Voltage vs. Temperature (VCC = 3.3 V, Data Rate = 500 kbps) Figure 22. ADM2687E Receiver Propagation Delay vs. Temperature 3.39 3.39 ISOLATED SUPPLY VOLTAGE (V) NO LOAD 3.37 RL = 120 3.36 RL = 54 3.35 3.34 3.36 NO LOAD 3.35 RL = 120 3.34 RL = 54 3.33 -15 10 35 60 85 TEMPERATURE (C) 3.31 -40 -15 10 35 60 85 TEMPERATURE (C) Figure 26. ADM2687E Isolated Supply Voltage vs. Temperature (VCC = 5 V, Data Rate = 500 kbps Figure 23. ADM2682E Isolated Supply Voltage vs. Temperature (VCC = 3.3 V, Data Rate = 16 Mbps) Rev. 0 | Page 12 of 24 09927-226 3.33 -40 3.37 3.32 09927-223 ISOLATED SUPPLY VOLTAGE (V) 3.38 3.38 ADM2682E/ADM2687E 60 40 40 RL = 120 30 20 NO LOAD 10 0 -40 -15 10 35 60 85 TEMPERATURE (C) Figure 27. ADM2682E Isolated Supply Current vs. Temperature (VCC = 3.3 V, Data Rate = 16 Mbps) 35 30 RL = 120 25 20 15 10 NO LOAD 5 0 -40 -15 10 35 60 85 TEMPERATURE (C) Figure 28. ADM2687E Isolated Supply Current vs. Temperature (VCC = 3.3 V, Data Rate = 500 kbps) Rev. 0 | Page 13 of 24 09927-228 ISOLATED SUPPLY CURRENT (mA) 50 09927-227 ISOLATED SUPPLY CURRENT (mA) RL = 54 RL = 54 ADM2682E/ADM2687E TEST CIRCUITS RL 2 VOD2 RL 2 VOC TxD 09927-003 Z VOUT Y Figure 32. Driver Enable/Disable 375 A 60 Z RxD VTEST B TxD VCC +1.5V CL S1 RL -1.5V CL 09927-005 Z CL Figure 33. Receiver Propagation Delay Figure 30. Driver Voltage Measurement over Common Mode Y VOUT RE RE RxD RL CL VOUT S2 RE IN Figure 31. Driver Propagation Delay Figure 34. Receiver Enable/Disable Rev. 0 | Page 14 of 24 09927-008 375 09927-004 VOD3 TxD S2 CL 50pF Z Figure 29. Driver Voltage Measurement Y RL 110 S1 DE VCC 09927-007 TxD 09927-006 Y ADM2682E/ADM2687E SWITCHING CHARACTERISTICS VCC VCC/2 VCC/2 0V tDPLH tDPHL VCC Z 1/2VO DE 90% POINT VDIFF tLZ 2.3V Y, Z 90% POINT VDIFF = V(Y) - V(Z) VOL + 0.5V VOL 10% POINT tZH 10% POINT tDF tDR tSKEW = tDPHL - tDPLH tHZ 2.3V VOH VOH - 0.5V Y, Z 09927-009 -VO 0.5VCC 0V tZL Y +VO 0.5VCC 09927-011 VO Figure 37. Driver Enable/Disable Timing Figure 35. Driver Propagation Delay, Rise/Fall Timing VIH RE 0.5VCC 0.5VCC VIL 0V 0V tRPLH tRPHL tZL 1.5V RxD VOH tLZ VOL + 0.5V OUTPUT LOW tZH OUTPUT HIGH 1.5V tSKEW = |tRPLH - tRPHL | 1.5V VOL 09927-010 RxD RxD 1.5V VOH - 0.5V 0V Figure 38. Receiver Enable/Disable Timing Figure 36. Receiver Propagation Delay Rev. 0 | Page 15 of 24 VOL tHZ VOH 09927-012 A-B ADM2682E/ADM2687E CIRCUIT DESCRIPTION SIGNAL ISOLATION Table 13. Receiving (see Table 11 for Abbreviations) 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. 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. 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 Inputs TxD H L X X Y H L Z Z Output RE L or NC L or NC L or NC L or NC H 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. 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. DC CORRECTNESS AND MAGNETIC FIELD IMMUNITY Table 12. Transmitting (see Table 11 for Abbreviations) DE H H L X Inputs A-B -0.03 V -0.2 V -0.2 V < A - B < -0.03 V Inputs open X Outputs Z L H Z Z 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 Rev. 0 | Page 16 of 24 ADM2682E/ADM2687E 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 The preceding magnetic flux density values correspond to specific current magnitudes at given distances from the ADM2682E/ADM2687E transformers. Figure 40 expresses these allowable current magnitudes as a function of frequency for selected distances. As shown in Figure 40, 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 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 39. 100 DISTANCE = 1m 100 10 DISTANCE = 100mm 1 DISTANCE = 5mm 0.1 0.01 10 10k 100k 1M 10M 100M MAGNETIC FIELD FREQUENCY (Hz) Figure 40. Maximum Allowable Current for Various Current-toADM2682E/ADM2687E Spacings 1 Note that in combinations of strong magnetic field and high frequency, any loops formed by 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. 0.1 10k 1M 10M 100k MAGNETIC FIELD FREQUENCY (Hz) 100M 09927-019 0.01 0.001 1k 1k 09927-020 MAXIMUM ALLOWABLE CURRENT (kA) 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). MAXIMUM ALLOWABLE MAGNETIC FLUX DENSITY (kgauss) 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. Figure 39. Maximum Allowable External Magnetic Flux Density Rev. 0 | Page 17 of 24 ADM2682E/ADM2687E 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 41). 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 Pin 10 and VCC at Pin 7 and Pin 8. Capacitor values of 0.01 F and 0.1 F are recommended for VISOIN at Pin 15 and Pin 16 and VCC at Pin 1 and Pin 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 1 16 VCC 2 15 RxD 3 ADM2682E/ ADM2687E GND2 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 the AN-0971 Application Note, Recommendations for Control of Radiated Emissions with isoPower Devices, for more information. VISOIN 14 A RE 4 13 B DE 5 12 Z TxD 6 11 Y VCC 7 10 GND1 8 9 10F 100nF The ADM2682E/ADM2687E dissipate approximately 675 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 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 41 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. VISOOUT GND2 10F 100nF 09927-125 10nF 100nF 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. Figure 41. Recommended PCB Layout Rev. 0 | Page 18 of 24 ADM2682E/ADM2687E INSULATION LIFETIME waveform that does not conform to Figure 43 or Figure 44 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. 0V 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. 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 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 cross-insulation voltage Figure 42. Bipolar AC Waveform RATED PEAK VOLTAGE 0V Figure 43. DC Waveform RATED PEAK VOLTAGE 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. 09927-022 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 42, Figure 43, and Figure 44 illustrate these different isolation voltage waveforms. 09927-021 RATED PEAK VOLTAGE 09927-023 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. Figure 44. Unipolar AC Waveform ISOLATED SUPPLY CONSIDERATIONS The typical output voltage of the integrated isoPower dc-to-dc isolated supply is 3.3 V. The isolated supply in the ADM2682E/ ADM2687E is typically capable of supplying a current of 55 mA when the junction temperature of the device is kept below 130C. This includes the current required by the internal RS-485 circuitry, and typically, no additional current is available on VISOOUT for external applications. Rev. 0 | Page 19 of 24 ADM2682E/ADM2687E TYPICAL APPLICATIONS Figure 46 and Figure 47 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. An example application of the ADM2682E/ADM2687E for a fullduplex RS-485 node is shown in the circuit diagram of Figure 45. Refer to the PCB Layout section for the recommended placement of the capacitors shown in this circuit diagram. Placement of the RT termination resistors depends on the location of the node and the network configuration. Refer to AN-960 Application Note, RS-485/RS-422 Circuit Implementation Guide, for guidance on termination. 3.3V/5V POWER SUPPLY 100nF 10F 100nF 10nF VCC VCC VISOOUT 100nF 10F isoPower DC-TO-DC CONVERTER OSCILLATOR RECTIFIER VISOIN 100nF REGULATOR DIGITAL ISOLATION iCoupler TxD DE ENCODE DECODE ENCODE DECODE DECODE ENCODE D Y Z A RxD RE R B RT ADM2682E/ADM2687E GND1 ISOLATION BARRIER GND2 GND1 Figure 45. Example Circuit Diagram Using the ADM2682E/ADM2687E Rev. 0 | Page 20 of 24 09927-124 MICROCONTROLLER AND UART TRANSCEIVER 10nF ADM2682E/ADM2687E MAXIMUM NUMBER OF TRANSCEIVERS ON BUS = 256 ADM2582E/ ADM2587E RxD R A A B B RE TxD RE Z D RxD R RT RT DE ADM2682E/ ADM2687E DE Z Y D Y A B ADM2682E/ ADM2687E R Z Y A D RxD RE B ADM2682E/ ADM2687E DE TxD R Z TxD Y D RxD RE DE TxD 09927-027 NOTES 1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE. 2. ISOLATION NOT SHOWN. Figure 46. ADM2682E/ADM2687E Typical Half Duplex RS-485 Network MAXIMUM NUMBER OF NODES = 256 MASTER SLAVE A R RxD B Y D RT RE DE Z D B RT Y A ADM2682E/ ADM2687E RE R RxD ADM2682E/ ADM2687E A B Z Y A B Z Y SLAVE SLAVE R ADM2682E/ ADM2687E RxD RE R D RxD RE DE TxD D ADM2682E/ ADM2687E DE TxD NOTES 1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE. 2. ISOLATION NOT SHOWN. Figure 47. ADM2682E/ADM2687E Typical Full Duplex RS-485 Network Rev. 0 | Page 21 of 24 09927-028 DE TxD TxD Z ADM2682E/ADM2687E OUTLINE DIMENSIONS 13.00 (0.5118) 12.60 (0.4961) 16 9 7.60 (0.2992) 7.40 (0.2913) 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10 10.65 (0.4193) 10.00 (0.3937) 8 2.65 (0.1043) 2.35 (0.0925) 1.27 (0.0500) BSC 0.51 (0.0201) 0.31 (0.0122) 0.75 (0.0295) 45 0.25 (0.0098) 8 0 SEATING PLANE 0.33 (0.0130) 0.20 (0.0079) 1.27 (0.0500) 0.40 (0.0157) 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. 10-12-2010-A 1 Figure 48. 16-Lead Standard Small Outline Package with Increased Creepage [SOIC_IC] Wide Body, (RI-16-1) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model 1 ADM2682EBRIZ ADM2682EBRIZ-RL7 ADM2687EBRIZ ADM2687EBRIZ-RL7 EVAL-ADM2682EEBZ EVAL-ADM2687EEBZ 1 Data Rate (Mbps) 16 16 0.5 0.5 Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C Z = RoHS Compliant Part. Rev. 0 | Page 22 of 24 Package Description 16-Lead SOIC_IC 16-Lead SOIC_IC 16-Lead SOIC_IC 16-Lead SOIC_IC ADM2682E Evaluation Board ADM2687E Evaluation Board Package Option RI-16-1 RI-16-1 RI-16-1 RI-16-1 ADM2682E/ADM2687E NOTES Rev. 0 | Page 23 of 24 ADM2682E/ADM2687E NOTES (c)2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09927-0-7/11(0) Rev. 0 | Page 24 of 24