3.3 V, Full-Duplex, 840 A, 20 Mbps, EIA RS-485 Transceiver ADM3491 Operates with 3.3 V supply EIA RS-422 and RS-485 compliant over full CM range 19 k input impedance Up to 50 transceivers on bus 20 Mbps data rate Short circuit protection Specified over full temperature range Thermal shutdown Interoperable with 5 V logic 840 A supply current 2 nA shutdown current Also available in TSSOP package Meets IEC1000-4-4 (>1 kV) 8 ns skew Upgrade for MAX 3491, SN75ALS180 APPLICATIONS Telecommunications DTE-DCE interface Packet switching Local area networks Data concentration Data multiplexers Integrated services digital network (ISDN) AppleTalk Industrial controls GENERAL DESCRIPTION The ADM3491 is a low power, differential line transceiver designed to operate using a single 3.3 V power supply. Low power consumption, coupled with a shutdown mode, makes it ideal for power-sensitive applications. It is suitable for communication on multipoint bus transmission lines. FUNCTIONAL BLOCK DIAGRAM ADM3491 A RO R B RE DE Z DI D Y 05234-001 FEATURES Figure 1. The ADM3491 is intended for balanced data transmission and complies with both EIA Standards RS-485 and RS-422. It contains a differential line driver and a differential line receiver, making it suitable for full-duplex data transfer. The input impedance is 19 k, allowing up to 50 transceivers to be connected on the bus. Excessive power dissipation caused by bus contention or by output shorting is prevented by a thermal shutdown circuit. This feature forces the driver output into a high impedance state, if a significant temperature increase is detected in the internal driver circuitry during fault conditions. The receiver contains a fail-safe feature that results in a logic high output state, if the inputs are unconnected (floating). The ADM3491 is fabricated on BiCMOS, an advanced mixed technology process combining low power CMOS with fast switching bipolar technology. The ADM3491 is fully specified over the industrial temperature range and is available in DIP and SOIC packages, as well as the space-saving TSSOP package. Rev. A 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) 2004 Analog Devices, Inc. All rights reserved. ADM3491 TABLE OF CONTENTS Specifications..................................................................................... 3 Typical Performance Characteristics ..............................................9 Timing Specifications .................................................................. 4 Applications Information .............................................................. 11 Absolute Maximum Ratings............................................................ 5 Differential Data Transmission ................................................ 11 ESD Caution.................................................................................. 5 Cable and Data Rate................................................................... 11 Pin Configurations and Function Descriptions ........................... 6 Receiver Open-Circuit Fail-Safe Feature ................................ 11 Test Circuits....................................................................................... 7 Outline Dimensions ....................................................................... 12 Switching Characteristics ................................................................ 8 Ordering Guide .......................................................................... 13 REVISION HISTORY 11/04--Rev. 0 to Rev. A Format Updated..................................................................Universal Changes to Specifications Section.................................................. 3 Changes to Ordering Guide .......................................................... 13 1/98--Revision 0: Initial Version Rev. A | Page 2 of 16 ADM3491 SPECIFICATIONS VCC = 3.3 V 0.3 V. All specifications TMIN to TMAX, unless otherwise noted. Table 1. Parameter DRIVER Differential Output Voltage, VOD |VOD| for Complementary Output States Common-Mode Output Voltage, VOC |VOC| for Complementary Output States CMOS Input Logic Threshold Low, VINL CMOS Input Logic Threshold High, VINH Logic Input Current (DE, DI, RE) Output Leakage (Y, Z) Current Output Short-Circuit Current RECEIVER Differential Input Threshold Voltage, VTH Input Voltage Hysteresis, VTH Input Resistance Input Current (A, B) Logic Enable Input Current (RE) Output Voltage Low, VOL Output Voltage High, VOH Short-Circuit Output Current Three-State Output Leakage Current POWER SUPPLY CURRENT ICC Supply Current in Shutdown Min Typ Max Unit Test Conditions/Comments V V V V V V V V A A mA RL = 100 , Figure 4, VCC > 3.1 V RL = 54 , Figure 4 RL = 60 , Figure 5, -7 V < VTST < +12 V R = 54 or 100 , Figure 4 R = 54 or 100 , Figure 4 R = 54 or 100 , Figure 4 -7 V < VCM < +12 V VCM = 0 V -7 V < VCM < +12 V VIN = 12 V VIN = -7 V 60 1.0 V mV k mA mA A V V mA A 1.5 1.5 1 mA mA A 2.0 1.5 1.5 0.2 3 0.2 0.8 2.0 1.0 3 250 -0.2 12 +0.2 50 19 1 -0.8 1 0.4 VCC - 0.4 V 0.84 0.84 0.002 Rev. A | Page 3 of 16 VO = -7 V or +12 V, VCC = 0 V or 3.6 V VO = -7 V or +12 V IOUT = 2.5 mA IOUT = -1.5 mA VOUT = GND or VCC VCC = 3.6 V, 0 V < VOUT < VCC Outputs unloaded DE = VCC, RE = 0 V DE = 0 V, RE = 0 V DE = 0 V, RE = VCC ADM3491 TIMING SPECIFICATIONS VCC = 3.3 V, TA = 25C. Table 2. Parameter DRIVER Differential Output Delay, TDD Differential Output Transition Time Propagation Delay Input to Output, TPLH, TPHL Driver Output to Output, TSKEW ENABLE/DISABLE Driver Enable to Output Valid Driver Disable Timing Driver Enable from Shutdown RECEIVER Time to Shutdown Propagation Delay Input to Output, TPLH, TPHL Skew, TPLH - TPHL Receiver Enable, TEN Receiver Disable, TDEN Receiver Enable from Shutdown Min Typ Max Unit Test Conditions/ Comments 1 1 7 8 22 35 15 35 8 ns ns ns ns RL = 60 , CL1 = CL2 = 15 pF, Figure 8 RL = 60 , CL1 = CL2 = 15 pF, Figure 8 RL = 27 , CL1 = CL2 = 15 pF, Figure 9 RL = 54 , CL1 = CL2 = 15 pF, Figure 9 45 40 650 90 80 110 ns ns ns RL = 110 , CL = 50 pF, Figure 6 RL = 110 , CL = 50 pF, Figure 6 RL = 110 , CL = 15 pF, Figure 6 190 65 300 90 10 50 45 500 ns ns ns ns ns ns CL = 15 pF, Figure 11 CL = 15 pF, Figure 11 CL = 15 pF, Figure 7 CL = 15 pF, Figure 7 CL = 15 pF, Figure 7 80 25 25 25 VCC = 3.3 V 0.3 V, TA = TMIN to TMAX. Table 3. Parameter DRIVER Differential Output Delay, TDD Differential Output Transition Time Propagation Delay Input to Output, TPLH, TPHL Driver Output to Output, TSKEW ENABLE/DISABLE Driver Enable to Output Valid Driver Disable Timing Driver Enable from Shutdown RECEIVER Time to Shutdown Propagation Delay Input to Output, TPLH, TPHL Skew, TPLH - TPHL Receiver Enable, TEN Receiver Disable, TDEN Receiver Enable from Shutdown Min Typ Max Unit Test Conditions/ Comments 1 2 7 8 22 70 15 70 10 ns ns ns ns RL = 60 , CL1 = CL2 = 15 pF, Figure 8 RL = 60 , CL1 = CL2 = 15 pF, Figure 8 RL = 27 , CL1 = CL2 = 15 pF, Figure 9 RL = 54 , CL1 = CL2 = 15 pF, Figure 9 45 40 650 110 110 110 ns ns ns RL = 110 , CL = 50 pF, Figure 6 RL = 110 , CL = 50 pF, Figure 6 RL = 110 , CL = 15 pF, Figure 6 190 65 500 115 20 50 50 600 ns ns ns ns ns ns CL = 15 pF, Figure 11 CL = 15 pF, Figure 11 CL = 15 pF, Figure 7 CL = 15 pF, Figure 7 CL = 15 pF, Figure 7 50 25 25 25 Rev. A | Page 4 of 16 ADM3491 ABSOLUTE MAXIMUM RATINGS TA = 25C, unless otherwise noted. Table 4. Parameter VCC Inputs Driver Input (DI) Control Inputs (DE, RE) Receiver Inputs (A, B) Outputs Driver Outputs Receiver Output 14-Lead DIP, Power Dissipation JA, Thermal Impedance 14-Lead SOIC, Power Dissipation JA, Thermal Impedance 16-Lead TSSOP, Power Dissipation JA, Thermal Impedance Operating Temperature Range Industrial (A Version) Storage Temperature Range Lead Temperature (Soldering, 10 s) Vapor Phase (60 s) Infrared (15 s) ESD Rating EFT Rating (IEC1000-4-4) Min 7V -0.3 V to VCC + 0.3 V -0.3 V to VCC + 0.3 V -7.5 V to +12.5 V Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and 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. -7.5 V to +12.5 V -0.5 V to VCC + 0.5 V 800 mW 140C/W 650 mW 115C/W 500 mW 158C/W -40C to +85C -65C to +150C 300C 215C 220C >2 kV >1 kV 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. A | Page 5 of 16 ADM3491 VCC 1 NC 16 NC 2 15 A ADM3491 14 B TOP VIEW (Not to Scale) 13 NC NC 1 14 VCC RO 3 RO 2 13 VCC RE 4 DE 5 12 Z DI 6 11 Y NC 7 10 NC GND 8 9 NC RE 3 ADM3491 12 A TOP VIEW 11 B (Not to Scale) DI 5 10 Z DE 4 9 GND 7 8 NC = NO CONNECT Y NC 05234-002 GND 6 NC = NO CONNECT Figure 2. DIP/SOIC Pin Configuration 05234-003 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS Figure 3. TSSOP Pin Configuration Table 5. Pin Function Descriptions Pin Number DIP/ SOIC 1, 8 TSSOP 2, 7, 9, 10, 13, 16 Mnemonic NC Description No Connect. 2 3 3 4 RO Receiver Output. High when A > B by 200 mV; low when A < B by 200 mV. RE 4 5 DE Receiver Output Enable. When RE is low, the receiver output RO is enabled. When RE is high, the output is high impedance. If RE is high and DE is low, the ADM3491 enters a shutdown state. Driver Output Enable. A high level enables the driver differential outputs, Y and Z. A low level places the part in a high impedance state. 5 6 DI Driver Input. When the driver is enabled, a logic low on DI forces Y low and Z high; a logic high on DI forces Y high and Z low. 6, 7 9 10 11 12 13, 14 8 11 12 14 15 1 GND Y Z B A VCC Ground Connection, 0 V. Noninverting Driver Output Y. Inverting Driver Output Z. Inverting Receiver Input B. Noninverting Receiver Input A. Power Supply, 3.3 V 0.3 V. Rev. A | Page 6 of 16 ADM3491 TEST CIRCUITS 375 R/2 05234-004 375 Figure 4. Driver Voltage Measurement Test Circuit Figure 8. Driver Voltage Measurement Test Circuit 2 VCC DE RL S1 CL VOUT DE IN RL S1 S2 05234-005 0V OR 3V VCC +1.5V RE -1.5V RE IN Figure 5. Driver Enable/Disable Test Circuit S2 CL VOUT 05234-009 VOC R/2 VCC VTST RL 05234-008 VOD3 VOD Figure 9. Receiver Enable/Disable Test Circuit VOM RL CL1 IN VOUT CL2 VOUT CL 05234-010 RLDIFF D S1 DE 05234-006 DI VCC Figure 6. Driver Differential Output Delay Test Circuit Figure 10. Driver Propagation Delay Test Circuit 3V RLDIFF B CL2 RO R RE VID 1.5V RE CL VOUT 05234-011 CL1 D 05234-007 DI 0V A Figure 11. Receiver Propagation Delay Test Circuit Figure 7. Driver/Receiver Propagation Delay Test Circuit Rev. A | Page 7 of 16 ADM3491 SWITCHING CHARACTERISTICS 3V 3V 1.5V 1.5V tPLH 0V Z RE 1.5V 1.5V 0V tPHL tZL tLZ 1/2VO VO 1.5V R tSKEW tSKEW VO 90% POINT VOL + 0.25V VOL tHZ tZH 90% POINT 0V VOH tR tF 05234-012 O/P HIGH 10% POINT 10% POINT R VOH - 0.25V 1.5V 0V Figure 14. Driver Enable/Disable Timing Figure 12. Driver Propagation Delay, Rise/Fall Timing 3V RE 1.5V 1.5V 0V tZL tLZ 0V 0V 1.5V R tPLH tPHL VOL + 0.25V VOL tHZ tZH VOH 1.5V O/P LOW VOH O/P HIGH 1.5V RO VOL R 1.5V VOH - 0.25V 0V Figure 13. Receiver Propagation Delay Figure 15. Receiver Enable/Disable Timing Rev. A | Page 8 of 16 05234-015 A-B 05234-013 -VO O/P LOW 05234-014 Y ADM3491 14 14 12 12 OUTPUT CURRENT (mA) 10 8 6 4 0 0 0.5 1 1.5 2 2.5 3 8 6 4 2 05234-016 2 10 0 3.5 05234-019 OUTPUT CURRENT (mA) TYPICAL PERFORMANCE CHARACTERISTICS 0 0.5 OUTPUT VOLTAGE (V) 1.5 2 2.5 3 3.5 4 OUTPUT HIGH VOLTAGE (V) Figure 16. Receiver Output Low Voltage vs. Output Current Figure 19. Receiver Output High Voltage vs. Output Current 3.3 0.8 0.7 3.25 0.6 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1 0.5 IRO = 2.5mA 0.4 0.3 3.2 IRO = -1.5mA 3.15 3.1 0.2 05234-017 0 -40 -20 0 20 40 60 80 3 -40 100 05234-020 3.05 0.1 -20 0 20 40 60 80 100 TEMPERATURE (C) TEMPERATURE (C) Figure 17. Receiver Output Low Voltage vs. Temperature Figure 20. Receiver Output High Voltage vs. Temperature 2.6 120 2.5 2.4 OUTPUT VOLTAGE (V) OUTPUT CURRENT (mA) 100 80 60 40 2.3 2.2 2.1 2.0 1.9 1.7 05234-018 0 0 0.5 1 1.5 2 DIFFERENTIAL O/P VOLTAGE (V) 2.5 05234-021 1.8 20 1.6 -40 3 -20 0 20 40 60 80 100 TEMPERATURE (C) Figure 21. Driver Differential Output Voltage vs. Temperature Figure 18. Driver Differential Output Voltage vs. Output Current Rev. A | Page 9 of 16 ADM3491 [ 1.2 ] 100FT CAT 5 CABLE T 1.1 3 T 1 T 0.9 1 2 0.7 -40 -20 0 20 40 60 80 T 4 100 CH1 1.00V CH3 2.00V TEMPERATURE (C) Figure 22. Supply Current vs. Temperature [ T 05234-024 05234-022 0.8 CH2 1.00V CH4 2.00V M40.0ns CH3 640mV Figure 24. Driving 100 ft. Cable H-L Transition ] 100 3 SHUTDOWN CURRENT (mA) 90 100FT CABLE T T 1 2 T T 80 70 60 50 40 30 4 CH1 1.00V CH3 2.00V CH2 1.00V CH4 2.00V M40.0ns CH3 05234-025 20 05234-023 SUPPLY CURRENT (mA) T 10 0 -40 640mV -20 0 20 40 TEMPERATURE (C) 60 Figure 25. Shutdown Current vs. Temperature Figure 23. Driving 100 ft. Cable L-H Transition Rev. A | Page 10 of 16 80 ADM3491 APPLICATIONS INFORMATION DIFFERENTIAL DATA TRANSMISSION Differential data transmission is used to reliably transmit data at high rates over long distances and through noisy environments. Differential transmission nullifies the effects of ground shifts and noise signals, which appear as common-mode voltages on the line. The two main standards approved by the Electronics Industries Association (EIA) specify the electrical characteristics of transceivers used in differential data transmission: * * RS-422 standard specifies data rates up to 10 MBaud and line lengths up to 4000 ft. A single driver can drive a transmission line with up to 10 receivers. As with any transmission line, it is important that reflections be minimized. This can be achieved by terminating the extreme ends of the line using resistors equal to the characteristic impedance of the line. Stub lengths of the main line should also be kept as short as possible. A properly terminated transmission line appears purely resistive to the driver. RECEIVER OPEN-CIRCUIT FAIL-SAFE FEATURE The receiver input includes a fail-safe feature that guarantees a logic high on the receiver when the inputs are open circuit or floating. 3.3V 3.3V 0.1F RS-485 standard was defined to cater to true multipoint communications. This standard meets or exceeds all the requirements of RS-422, but also allows multiple drivers and receivers to be connected to a single bus. An extended common-mode range of -7 V to +12 V is defined. RE 0.1F VCC VCC A Y B Z DE DI RO R ADM3491 RS-485/RS-422 LINK D ADM3491 Z B Y A RO DI D The most significant differentiator of the RS-485 standard is that the drivers can be disabled, thereby allowing more than one to be connected to a single line. Only one driver should be enabled at a time, but the RS-485 standard contains additional specifications to guarantee device safety in the event of line contention. Table 6. Comparison of RS-422 and RS-485 Interface Standards Specification Transmission Type Maximum Cable Length Minimum Driver Output Voltage Driver Load Impedance Receiver Input Resistance Receiver Input Sensitivity Receiver Input Voltage Range RS-422 Differential 4000 ft. 2 V 100 4 k min 200 mV -7 V to +7 V R RE DE GND 05234-026 GND Figure 26. ADM3491 Full-Duplex Data Link Table 7. Transmitting Truth Table Transmitting RS-485 Inputs Differential 4000 ft. 1.5 V 54 12 k min 200 mV -7 V to +12 V RE X X 0 1 DE 1 1 0 0 Outputs DI 1 0 X X Z 0 1 Hi-Z Hi-Z Y 1 0 Hi-Z Hi-Z Table 8. Receiving Truth Table Receiving Inputs CABLE AND DATA RATE The transmission line of choice for RS-485 communications is a twisted pair. Twisted pair cable tends to cancel common-mode noise and also causes cancellation of the magnetic fields generated by the current flowing through each wire, thereby reducing the effective inductance of the pair. RE 0 0 0 1 The ADM3491 is designed for bidirectional data communications on multipoint transmission lines. A typical application showing a multipoint transmission network is illustrated in Figure 26. Only one driver can transmit at a particular time, but multiple receivers can be enabled simultaneously. Rev. A | Page 11 of 16 DE X X X X A-B > +0.2 V < -0.2 V Inputs O/C X Outputs RO 0 0 1 Hi-Z ADM3491 OUTLINE DIMENSIONS 0.685 (17.40) 0.665 (16.89) 0.645 (16.38) 14 8 1 7 0.295 (7.49) 0.285 (7.24) 0.275 (6.99) 0.100 (2.54) BSC 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.015 (0.38) MIN 0.180 (4.57) MAX 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) SEATING 0.022 (0.56) 0.060 (1.52) PLANE 0.018 (0.46) 0.050 (1.27) 0.014 (0.36) 0.045 (1.14) 0.150 (3.81) 0.135 (3.43) 0.120 (3.05) 0.015 (0.38) 0.010 (0.25) 0.008 (0.20) COMPLIANT TO JEDEC STANDARDS MO-095-AB CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN Figure 27. 14-Lead Plastic DIP (N-14) Dimensions shown in inches and (millimeters) 8.75 (0.3445) 8.55 (0.3366) 4.00 (0.1575) 3.80 (0.1496) 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 14 8 1 7 1.27 (0.0500) BSC 0.51 (0.0201) 0.31 (0.0122) 6.20 (0.2441) 5.80 (0.2283) 1.75 (0.0689) 1.35 (0.0531) SEATING PLANE 0.50 (0.0197) x 45 0.25 (0.0098) 8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012AB 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 28. 14-Lead Narrow Body Small Outline (SOIC) (R-14) Dimensions shown in inches and (millimeters) Rev. A | Page 12 of 16 ADM3491 5.10 5.00 4.90 16 9 4.50 4.40 4.30 6.40 BSC 1 8 PIN 1 1.20 MAX 0.15 0.05 0.20 0.09 0.30 0.19 0.65 BSC COPLANARITY 0.10 SEATING PLANE 8 0 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MO-153AB Figure 29. 16-Lead Thin Shrink Small Outline (TSSOP) (RU-16) Dimensions shown in inches and (millimeters) ORDERING GUIDE Model ADM3491AN ADM3491AR ADM3491AR-REEL ADM3491AR-REEL7 ADM3491ARZ1 ADM3491ARZ-REEL1 ADM3491ARZ-REEL71 ADM3491ARU ADM3491ARU-REEL ADM3491ARU-REEL7 ADM3491ARUZ1 ADM3491ARUZ-REEL1 ADM3491ARUZ-REEL71 1 Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C Package Description 14-Lead Plastic DIP 14-Lead Narrow Body Small Outline (SOIC) 14-Lead Narrow Body Small Outline (SOIC) 14-Lead Narrow Body Small Outline (SOIC) 14-Lead Narrow Body Small Outline (SOIC) 14-Lead Narrow Body Small Outline (SOIC) 14-Lead Narrow Body Small Outline (SOIC) 16-Lead Thin Shrink Small Outline (TSSOP) 16-Lead Thin Shrink Small Outline (TSSOP) 16-Lead Thin Shrink Small Outline (TSSOP) 16-Lead Thin Shrink Small Outline (TSSOP) 16-Lead Thin Shrink Small Outline (TSSOP) 16-Lead Thin Shrink Small Outline (TSSOP) Z = Pb-free part. Rev. A | Page 13 of 16 Package Options N-14 R-14 R-14 R-14 R-14 R-14 R-14 RU-16 RU-16 RU-16 RU-16 RU-16 RU-16 ADM3491 NOTES Rev. A | Page 14 of 16 ADM3491 NOTES Rev. A | Page 15 of 16 ADM3491 NOTES (c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C05234-0-11/04(A) Rev. A | Page 16 of 16