3.3 V Slew Rate Limited, Half Duplex RS-485/RS-422 Transceiver ADM3493 Operates with 3.3 V supply Interoperable with 5 V logic EIA RS-422 and RS-485 compliant over full CM range Data rate: 250 kbps Half duplex transceiver Reduced slew rates for low EMI 2 nA supply current in shutdown mode Up to 256 transceivers on a bus −7 V to +12 V bus common-mode range Specified over −40°C to +85°C temperature range 8 ns skew Available in 8-lead SOIC FUNCTIONAL BLOCK DIAGRAM VCC ADM3493 R RO A RE DE DI B D GND 05715-001 FEATURES Figure 1. APPLICATIONS Low power RS-485 applications EMI sensitive systems DTE-DCE interfaces Industrial control Packet switching Local area networks Level translators GENERAL DESCRIPTION The ADM3493 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. The ADM3493 is suitable for communication on multipoint bus transmission lines. The device contains one driver and one receiver. Designed for half-duplex communication, the ADM3493 features a slew rate limited driver that minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission at data rates up to 250 kbps. The receiver input impedance is 96 kΩ, allowing up to 256 transceivers to be connected on the bus. A thermal shutdown circuit prevents excessive power dissipation caused by bus contention or by output shorting. If a significant temperature increase is detected in the internal driver circuitry during fault conditions then the thermal shutdown circuit forces the driver output into a high impedance state. The receiver contains a failsafe feature that results in a logic high output state, if the inputs are unconnected (floating). The ADM3493 is fully specified over the commercial and industrial temperature ranges and is available in an 8-lead SOIC. 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 ©2005 Analog Devices, Inc. All rights reserved. ADM3493 TABLE OF CONTENTS Features .............................................................................................. 1 Switching Characteristics .................................................................8 Applications....................................................................................... 1 Typical Performance Characteristics ..............................................9 Functional Block Diagram .............................................................. 1 Circuit Description......................................................................... 11 General Description ......................................................................... 1 Reduced EMI and Reflections .................................................. 11 Revision History ............................................................................... 2 Low Power Shutdown Mode..................................................... 11 Specifications..................................................................................... 3 Driver Output Protection.......................................................... 11 Timing Specifications .................................................................. 4 Propagation Delay ...................................................................... 11 Absolute Maximum Ratings............................................................ 5 Typical Applications................................................................... 11 ESD Caution.................................................................................. 5 Outline Dimensions ....................................................................... 12 Pin Configurations and Function Descriptions ........................... 6 Ordering Guide .......................................................................... 12 Test Circuits....................................................................................... 7 REVISION HISTORY 10/05—Rev. 0: Initial Version Rev. 0 | Page 2 of 12 ADM3493 SPECIFICATIONS VCC = 3.3 V ±0.3 V, TA = TMIN to TMAX, unless otherwise noted. Table 1. Parameter DRIVER Differential Output Voltage, VOD Δ |VOD| for Complementary Output States 1 Common-Mode Output Voltage, VOC Δ |VOC| for Common-Mode Output Voltage1 DRIVER INPUT LOGIC CMOS Input Logic Threshold Low, VIH CMOS Input Logic Threshold High, VIL CMOS Logic Input Current, IN1 Min Typ Units Test Conditions/Comments 2.0 V 1.5 1.5 V V 0.2 3 0.2 V V V RL = 100 Ω (RS-422), Vcc = 3.3 V ±5% (see Figure 3) RL = 54 Ω (RS-485) (see Figure 3) RL = 60 Ω (RS-485), Vcc = 3.3 V (see Figure 4) RL = 54 Ω or 100 Ω (see Figure 3) RL = 54 Ω or 100 Ω (see Figure 3) RL = 54 Ω or 100 Ω (see Figure 3) 0.8 V V μA DE, DI, RE DE, DI, RE DE, DI, RE 60 μA VIN = 12 V −60 μA VIN = −7 V 0.2 V mV V 0.4 V ±1 μA kΩ −7V < VCM < + 12 V VCM = 0 V IOUT = −1.5 mA, VID = 200 mV (see Figure 5) IOUT = 2.5mA, VID = 200mV (see Figure 5) Vcc = 3.6 V, 0 V ≤ VOUT ≤ Vcc −7 V < VCM < + 12 V 1.1 2.2 mA DE = VCC 0.95 1.9 mA 2.0 ±2 Input Current (A, B), IN2 RECEIVER Differential Input Threshold Voltage, VTH Input Hysteresis, Δ VTH CMOS Output Voltage High, VOH Max −0.2 50 Vcc – 0.4 CMOS Output Voltage Low, VOL Three-State Output Leakage Current, IOZR Input Resistance, RIN POWER SUPPLY CURRENT Supply Current 96 DE = 0 V VCC = 0 V or 3.6 V RE = 0 V or VCC DE = VCC No load, DI = 0 V or VCC RE = 0 V Supply Current in Shutdown Mode, ISHDN 0.002 Driver Short-Circuit Output Current, IOSD Receiver Short-Circuit Output Current, IOSR 1 ±8 ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when DI input changes state. Rev. 0 | Page 3 of 12 1 μA −250 250 ±60 mA mA mA DE = 0 V, RE = VCC, DI = VCC or 0 V VOUT = −7 V VOUT = 12 V 0 V < VRO < VCC ADM3493 TIMING SPECIFICATIONS VCC = 3.3 V, TA = 25°C, unless otherwise noted. Table 2. Parameter DRIVER Differential Output Delay, tDD Differential Output Transition Time, tTD Propagation Delay, Low-to-High Level, tPLH Propagation Delay, High-to-Low Level, tPHL |tPLH – tPHL| Propagation Delay Skew1, tPDS DRIVER OUTPUT ENABLE/DISABLE TIMES Output Enable Time to Low Level, tPZL Output Enable Time to High Level, tPZH Output Disable Time from High Level, tPHZ Min Typ Max Units Test Conditions/Comments 600 400 700 700 900 700 1000 1000 100 1400 1200 1500 1500 ns ns ns ns ns RL = 60 Ω (see Figure 6 and Figure 12) RL = 60 Ω (see Figure 6 and Figure 12) RL = 27 Ω (see Figure 7 and Figure 13) RL = 27 Ω (see Figure 7 and Figure 13) RL = 27 Ω (see Figure 7 and Figure 13) 1300 800 80 ns ns ns RL = 110 Ω (see Figure 9 and Figure 15) RL = 110 Ω (see Figure 8 and Figure 14) RL = 110 Ω (see Figure 8 and Figure 14) 900 600 50 Output Disable Time from Low Level, tPLZ 50 80 ns Output Enable Time from Shutdown to Low Level, tPSL Output Enable Time from Shutdown to High Level, tPSH RECEIVER Time to Shutdown2, tSHDN Propagation Delay, Low-to-High Level, tRPLH 1.9 2.7 μs RL = 110 Ω (see Figure 9 and Figure 15) RL = 110 Ω (see Figure 9 and Figure 15) 2.2 3.0 μs RL = 110 Ω (see Figure 8 and Figure 14) 80 25 190 75 300 180 ns ns Propagation Delay, High-to-Low Level, tRPHL 25 75 180 ns 50 ns 25 25 25 25 720 50 50 45 45 1400 ns ns ns ns ns CL = 15 pF (see Figure 11 and Figure 17) CL = 15 pF (see Figure 11 and Figure 17) CL = 15 pF (see Figure 11 and Figure 17) CL = 15 pF (see Figure 11 and Figure 17) CL = 15 pF (see Figure 11 and Figure 17) 720 1400 ns CL = 15 pF (see Figure 11 and Figure 17) |tPLH – tPHL| Propagation Delay Skew, tRPDS RECEIVER OUTPUT ENABLE/DISABLE TIMES Output Enable Time to Low Level, tPRZL Output Enable Time to High Level, tPRZH Output Disable Time from High Level, tPRHZ Output Disable Time from Low Level, tPRLZ Output Enable Time from Shutdown to Low Level, tPRSL Output Enable Time from Shutdown to High Level, tPRSH 1 2 VID = 0 V to 3.0 V, CL = 15 pF (see Figure 10 and Figure 16) VID = 0 V to 3.0 V, CL = 15 pF (see Figure 10 and Figure 16) VID = 0 V to 3.0 V, CL = 15 pF (see Figure 10 and Figure 16) Measured on |tPLH (A) − tPHL (A)| and |tPLH (B) − tPHL (B)|. The transceivers are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 80 ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 300 ns, the parts are guaranteed to enter shutdown. Rev. 0 | Page 4 of 12 ADM3493 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 3. Parameter VCC to GND Digital I/O Voltage (DE, RE, DI) Digital I/O Voltage (ROUT) Driver Output/Receiver Input Voltage Operating Temperature Range Storage Temperature Range θJA Thermal Impedance 8-Lead SOIC Lead Temperature Soldering (10 seconds) Vapor Phase (60 seconds) Infrared (15 seconds) Rating 7V −0.3 V to VCC + 0.3 V VCC − 0.5 V to VCC + 0.5 V −7.5 V to +12.5 V −40°C to +85°C −65°C to +125°C 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. 121°C/W 300°C 215°C 220°C 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. 0 | Page 5 of 12 ADM3493 RO 1 RE 2 DE 3 DI 4 ADM3493 TOP VIEW (Not to Scale) 8 VCC 7 B 6 A 5 GND 05715-002 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Figure 2. Pin Configuration Table 4. . Pin Function Descriptions Pin No. 1 Mnemonic RO 2 RE 3 DE 4 DI 5 6 7 8 GND A B VCC Description Receiver Output. When enabled, if A > B by 200 mV, then RO = high. If A < B by 200 mV, then RO = low. Receiver Output Enable. A low level enables the receiver output, RO. A high level places it in a high impedance state. If RE is high and DE is low, the device enters a low power shutdown mode. Driver Output Enable. A high level enables the driver differential Outputs A and B. A low level places it in a high impedance state. If RE is high and DE is low, the device enters a low power shutdown mode. Driver Input. When the driver is enabled, a logic low on DI forces A low and B high while a logic high on DI forces A high and B low. Ground. Noninverting Receiver Input A and Noninverting Driver Output A. Inverted Receiver Input B and Inverted Driver Output B. Power Supply, 3.3 V ± 0.3 V. Rev. 0 | Page 6 of 12 ADM3493 TEST CIRCUITS S1 A 0V OR 3V OUT CL = 50pF2 VOD VOC GENERATOR1 05715-003 RL/2 B RL = 110Ω 50Ω VOM = VOH + VOL Figure 3. Driver VOD and VOC 2 ≈ 1.5V 05715-008 RL/2 D 1PPR = 250kHz, 50% DUTY CYCLE, t ≤ 6.0ns, Z = 50Ω. R O 2C INCLUDES PROBE AND STRAY CAPACITANCE. L 375Ω Figure 8. Driver Enable and Disable Times (tPZH, tPSH, tPHZ) VOD RL VCC VCC RL = 110Ω 05715-004 D VCM = –7V TO +12V 375Ω S1 0V OR 3V CL = 50pF2 GENERATOR1 VID OUT D Figure 4. Driver VOD with Varying Common-Mode Voltage 50Ω R IOL (+) VOH IOH (–) 1PPR = 250kHz, 50% DUTY CYCLE, t ≤ 6.0ns, Z = 50Ω. R O 2C INCLUDES PROBE AND STRAY CAPACITANCE. L 05715-005 VOL Figure 9. Driver Enable and Disable Times (tPZL, tPSL, tPLZ) Figure 5. Receiver VOH and VOL CL VID RL = OUT 60Ω D GENERATOR1 R 50Ω OUT CL = 15pF2 50Ω CL = 15pF2 1.5V 1PPR = 250kHz, 50% DUTY CYCLE, t ≤ 6.0ns, Z = 50Ω. R O 2C INCLUDES PROBE AND STRAY CAPACITANCE. L VOM = 0 VCC 2 1PPR = 250kHz, 50% DUTY CYCLE, t ≤ 6.0ns, Z = 50Ω. R O 2C INCLUDES PROBE AND STRAY CAPACITANCE. L Figure 6. Driver Differential Output Delay and Transition Times 05715-010 VCC 05715-006 GENERATOR1 05715-009 0 Figure 10. Receiver Propagation Delay VOM +1.5V RL = 27Ω S1 S3 VID –1.5V R S1 CL = 15pF2 50Ω GENERATOR1 VCC VOH + VOL 2 ≈ 1.5V 1PPR = 250kHz, 50% DUTY CYCLE, t ≤ 6.0ns, Z = 50Ω. R O 2C INCLUDES PROBE AND STRAY CAPACITANCE. L 05715-007 VOM = 50Ω 1PPR = 250kHz, 50% DUTY CYCLE, t ≤ 6.0ns, Z = 50Ω. R O 2C INCLUDES PROBE AND STRAY CAPACITANCE. L Figure 7. Driver Propagation Delays Figure 11. Receiver Enable and Disable Times Rev. 0 | Page 7 of 12 05715-011 GENERATOR1 S2 CL2 OUT D VCC 1kΩ ADM3493 SWITCHING CHARACTERISTICS 3V +3V IN 1.5V 1.5V 1.5V 0 0 50% 10% 90% 90% tTD VCC ≈ +2V 50% 10% tTD ≈ –2V tPLZ OUT VOM 0.25V VOL Figure 15. Driver Enable and Disable Times (tPZL, tPSL, tPLZ) Figure 12. Driver Differential Output Delay and Transition Times 3V 3V IN 1.5V 1.5V IN 1.5V 1.5V 0 0V tPLH tRPLH tPHL tRPHL VOH A OUT VOM VCC VOM VOM OUT VOM VOL tPHL 0 tPLH Figure 16. Receiver Propagation Delay VOM VOM VOL 05715-013 VOH B OUT +3V +1.5V IN tPRZH tPRSH Figure 13. Driver Propagation Delays OUT 1.5V +1.5V IN +1.5V tPHZ +1.5V VOL S1 OPEN S2 CLOSED S3 = +1.5V +3V +1.5V IN 0 tPRHZ VOH 0 05715-014 VOM OUT +0.25V VCC OUT +0.25V Figure 17. Receiver Enable and Disable Times Rev. 0 | Page 8 of 12 S1 CLOSED S2 OPEN S3 = –1.5V tPRLZ VOH 0 Figure 14. Driver Enable and Disable Times (tPZH, tPSH, tPHZ) S1 CLOSED S2 OPEN S3 = –1.5V VCC OUT 0 0.25V 0 tPRZL tPRSL VOH +3V 0 OUT +3V IN 0 1.5V tPZH S1 OPEN S2 CLOSED S3 = +1.5V +1.5V 3V IN 0 VOL 05715-017 OUT tPSL tDD 05715-012 tDD 05715-015 1.5V 05715-016 IN ADM3493 TYPICAL PERFORMANCE CHARACTERISTICS 30 0.8 0.7 0.6 OUTPUT VOLTAGE (V) 20 15 10 0.5 0.4 0.3 0.2 5 05715-018 0 0.1 0 0.5 1.0 1.5 2.0 2.5 0 –40 –30 –20 –10 3.5 3.0 05715-021 OUTPUT CURRENT (mA) 25 0 OUTPUT VOLTAGE (V) 10 20 30 40 50 60 70 80 TEMPERATURE (°C) Figure 18. Output Current vs. Receiver Output Low Voltage Figure 21. Receiver Output Low Voltage vs. Temperature, IO = 2.5 mA –16 100 90 –14 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 80 –12 –10 –8 –6 –4 70 60 50 40 30 05715-019 0 0 0.5 1.0 1.5 2.0 2.5 10 0 3.5 3.0 05715-022 20 –2 0 0.5 1.0 OUTPUT VOLTAGE (V) 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V) Figure 19. Output Current vs. Receiver Output High Voltage Figure 22. Driver Output Current vs. Differential Output Voltage 3.30 2.6 2.5 2.4 OUTPUT VOLTAGE (V) 3.20 3.15 3.10 2.2 2.1 2.0 1.9 1.8 05715-020 3.05 3.00 –40 –30 –20 –10 2.3 0 10 20 30 40 50 60 70 1.7 1.6 –40 –30 –20 –10 80 TEMPERATURE (°C) Figure 20. Receiver Output High Voltage vs. Temperature, IO = 1.5 mA 05715-023 OUTPUT VOLTAGE (V) 3.25 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) Figure 23. Driver Differential Output Voltage vs. Temperature, RI = 54 Ω Rev. 0 | Page 9 of 12 ADM3493 140 1.2 1.1 120 SUPPLY CURRENT (mA) OUTPUT CURRENT (mA) 1.0 100 80 60 40 0.9 0.8 0.7 DE = RE = X* 0.6 0.5 05715-024 0 0 2 4 6 8 0.3 12 10 DE = RE = GND 0.2 –40 –30 –20 –10 *X = DON’T CARE 0 OUTPUT VOLTAGE (V) 30 40 50 60 70 80 70 80 Figure 26. Supply Current vs. Temperature –125 100 –115 90 –105 80 SHUTDOWN CURRENT (nA) –95 –85 –75 –65 –55 –45 –35 –25 70 60 50 40 30 20 –5 –6 –5 –4 –3 –2 –1 0 1 2 05715-027 10 –15 05715-025 OUTPUT CURRENT (mA) 20 TEMPERATURE (°C) Figure 24. Output Current vs. Driver Output Low Voltage –7 10 05715-026 0.4 20 0 –10 –40 –30 –20 –10 3 OUTPUT VOLTAGE (V) 0 10 20 30 40 50 60 TEMPERATURE (°C) Figure 25. Output Current vs. Driver Output High Voltage Figure 27. Shutdown Current vs. Temperature, VCC = 3.3 V Rev. 0 | Page 10 of 12 ADM3493 CIRCUIT DESCRIPTION The ADM3493 is a low power transceiver for RS-485 and RS-422 communications. The ADM3493 can transmit and receive at data rates up to 250 kbps in a half duplex configuration. Driver Enable (DE) and Receiver Enable (RE) pins are included when disabled; the driver and receiver outputs are high impedance. Table 5. Transmitting Truth Table Transmitting Inputs 2 DE DI X1 X1 0 1 1 1 0 0 1 0 X1 X1 0 1 High-Z2 High-Z2 Mode DRIVER OUTPUT PROTECTION 1 0 High-Z2 High-Z2 Normal Normal Normal Shutdown X = Don’t care. High-Z = High Impedance. Table 6. Receiving Truth Table Receiving Inputs RE DE A-B Receiving Outputs RO 0 0 0 1 0 0 0 0 ≥+0.2 V ≤−0.2 V Inputs Open X1 1 0 1 High-Z2 Mode Normal Normal Normal Shutdown 1 X = Don’t care. 2 High-Z = High Impedance REDUCED EMI AND REFLECTIONS The ADM3493 is a slew rate limited transceiver, minimizing EMI and reducing reflections caused by improperly terminated cables. R Two methods are implemented to prevent excessive output current and power dissipation caused by faults or by bus contention. Current limit protection on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Performance Characteristics). In addition, a thermal shutdown circuit forces the driver outputs into a high impedance state if the die temperature rises excessively. PROPAGATION DELAY Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle). The receiver skew time, |tPRLH - tPRHL|, is 20 ns for the ADM3493. The driver skew time is typically under 100 ns. TYPICAL APPLICATIONS The ADM3493 transceiver is designed for bidirectional data communications on multipoint bus transmission lines. Figure 22 shows a typical network application’s circuits. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew rate limited ADM3493 is tolerant of imperfect termination. MAXIMUM NUMBER OF TRANSCEIVERS ON BUS = 256 ADM3493 RO A low power shutdown mode is initiated by bringing both RE high and DE low. The ADM3493 does not shut down unless both the driver and receiver are disabled (high impedance). In shutdown, the ADM3493 typically draws only 2 nA of supply current. For the ADM3493, the tPSH and tPSL enable times assume the part was in the low power shutdown mode; the tPZH and tPZL enable times assume the receiver or driver was disabled, but the part was not shut down. ADM3493 VCC A R1 A R RO RE RT RE RT DE DI DE D B B R2 A A B ADM3493 R R D RE DI B ADM3493 RO D DE RO DI D RE DE DI NOTES 1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE. Figure 28. ADM3493 Typical Half Duplex RS-485 Network Rev. 0 | Page 11 of 12 05715-028 1 RE Transmitting Outputs B A LOW POWER SHUTDOWN MODE ADM3493 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 4.00 (0.1574) 3.80 (0.1497) 1 5 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 6.20 (0.2440) 4 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 0.50 (0.0196) × 45° 0.25 (0.0099) 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012-AA 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 29. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model ADM3493ARZ1 Temperature Range −40°C to +85°C Package Description 8-Lead Standard Small Outline Package [SOIC_N] Package Options R-8 ADM3493ARZ-REEL71 −40°C to +85°C 8-Lead Standard Small Outline Package [SOIC_N] R-8 1 Z = Pb-free part. © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05715-0-10/05(0) Rev. 0 | Page 12 of 12 Ordering Quantity 1,000