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| 5 V Low Power, Slew-Rate Limited RS-485/RS-422 Transceiver ADM483 FEATURES EIA RS-485/RS-422-compliant Data rates up to 250 kbps Slew-rate limited for low EMI 100 nA supply current in shutdown mode Low power consumption (120 A) Up to 32 transceivers on one bus Outputs high-z when disabled or powered off -7 V to +12 V bus common-mode range Thermal shutdown and short-circuit protection Pin-compatible with MAX483 Specified over -40C to +85C temperature range Available in 8-lead SOIC package FUNCTIONAL BLOCK DIAGRAM VCC ADM483 RO RE DE DI D 05079-001 R A B GND 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 ADM483 is a low power differential line transceiver suitable for half-duplex data communication on multipoint bus transmission lines. It is designed for balanced data transmission, and complies with EIA Standards RS-485 and RS-422.The part contains a differential line driver and a differential line receiver. Both share the same differential pins, with either the driver or the receiver being enabled at any given time. The device has an input impedance of 12 k, allowing up to 32 transceivers on one bus. Since only one driver should be enabled at any time, the output of a disabled or powered-down driver is three-stated to avoid overloading the bus. This high impedance driver output is maintained over the entire common-mode voltage range from -7 V to +12 V. The receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating). The driver outputs are slew-rate limited to reduce EMI and data errors caused by reflections from improperly terminated buses. Excessive power dissipation caused by bus contention or by output shorting is prevented by a thermal shutdown circuit. The part is fully specified over the industrial temperature range, and is available in an 8-lead SOIC package. 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: 781.326.8703 (c) 2004 Analog Devices, Inc. All rights reserved. ADM483 TABLE OF CONTENTS Specifications..................................................................................... 3 Timing Specifications....................................................................... 4 Absolute Maximum Ratings............................................................ 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Descriptions............................. 6 Test Circuits....................................................................................... 7 Switching Characteristics ................................................................ 8 Typical Performance Characteristics ............................................. 9 Applications..................................................................................... 11 Differential Data Transmission ................................................ 11 Cable and Data Rate................................................................... 11 Thermal Shutdown .................................................................... 12 Receiver Open-Circuit Fail-Safe............................................... 12 Outline Dimensions ....................................................................... 13 Ordering Guide .......................................................................... 13 REVISION HISTORY 10/04--Revision 0: Initial Version Rev. 0 | Page 2 of 16 ADM483 SPECIFICATIONS VCC = 5 V 5%, TA = TMIN to TMAX, unless otherwise noted. Table 1. Parameter DRIVER Differential Output Voltage, VOD Min Typ Max 5 2.0 1.5 1.5 |VOD| for Complementary Output States Common-Mode Output Voltage, VOC |VOC| for Complementary Output States Output Short-Circuit Current, VOUT = High Output Short-Circuit Current, VOUT = Low DRIVER INPUT LOGIC CMOS Input Logic Threshold Low CMOS Input Logic Threshold High CMOS Logic Input Current (DI) DE Input Resistance to GND RECEIVER Differential Input Threshold Voltage, VTH Input Hysteresis Input Resistance (A, B) Input Current (A, B) CMOS Logic Input Current (RE) CMOS Output Voltage Low CMOS Output Voltage High Output Short-Circuit Current Three-State Output Leakage Current POWER SUPPLY CURRENT 5 5 0.2 3 0.2 250 250 0.8 2.0 2 220 -200 70 12 1 -0.8 2 0.4 3.5 7 0.1 120 350 95 2 10 250 650 +200 Unit V V V V V V V mA mA V V A k mV mV k mA mA A V V mA A A A A -7 V < VCM < +12 V VCM = 0V -7 V < VCM < +12 V VIN = +12 V VIN = -7 V IOUT = 4 mA IOUT = -4 mA 0 V < VOUT < VCC 0.4 VOUT 2.4 V DE = 0 V, RE = VCC (shutdown) DE = 0 V, RE = 0 V DE = VCC Test Conditions/Comments R = , Figure 3 R = 50 (RS-422), Figure 3 R = 27 (RS-485), Figure 3 VTST = -7 V to 12 V, Figure 4 R = 27 or 50 , Figure 3 R = 27 or 50 , Figure 3 R = 27 or 50 , Figure 3 -7 V < VOUT < +12 V -7 V < VOUT < +12 V 35 35 Rev. 0 | Page 3 of 16 ADM483 TIMING SPECIFICATIONS VCC = 5 V 5%, TA = TMIN to TMAX, unless otherwise noted. Table 2. Parameter DRIVER Maximum Data Rate Propagation Delay tPLH, tPHL Skew tSKEW Rise/Fall Time tR, tF Enable Time Disable Time Enable Time from Shutdown RECEIVER Propagation Delay tPLH, tPHL Differential Skew tSKEW Enable Time Disable Time Enable Time from Shutdown Time to Shutdown1 Min 250 250 200 125 125 Typ Max Unit kbps ns ns ns ns ns ns ns ns ns ns ns ns Test Conditions/Comments 800 100 2000 800 2000 2000 3000 5000 2000 RLDIFF = 54 , CL1 = CL2 = 100 pF, Figure 5 RLDIFF = 54 , CL1 = CL2 = 100 pF, Figure 5 RLDIFF = 54 , CL1 = CL2 = 100 pF, Figure 5 RL = 500 , CL = 100 pF, Figure 6 RL = 500 , CL = 15 pF, Figure 6 RL = 500 , CL = 100 pF, Figure 6 CL = 15 pF, Figure 7 CL = 15 pF, Figure 7 RL = 1 k, CL = 15 pF, Figure 8 RL = 1 k, CL = 15 pF, Figure 8 RL = 1 k, CL = 15 pF, Figure 8 250 100 20 20 50 330 50 50 5000 3000 1 The device is put into shutdown mode by driving RE high and DE low. If these inputs are in this state for less than 50 ns, the device is guaranteed not to enter shutdown mode. If the enable inputs are in this state for at least 3000 ns, the device is guaranteed to have entered shutdown mode. Rev. 0 | Page 4 of 16 ADM483 ABSOLUTE MAXIMUM RATINGS TA = 25C, unless otherwise noted. Table 3. Parameter VCC to GND Digital I/O Voltage (DE, RE, DI, ROUT) Driver Output/Receiver Input Voltage Operating Temperature Range Storage Temperature Range JA Thermal Impedance (SOIC) Lead Temperature Soldering (10 s) Vapor Phase (60 s) Infrared (15 s) Rating 6V -0.3 V to VCC + 0.3 V -9 V to +14 V -40C to +85C -65C to +125C 110C/W 300C 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. 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 16 ADM483 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS RO 1 RE 2 DE 3 8 VCC B 05079-002 ADM483 7 6A TOP VIEW (Not to Scale) 5 GND DI 4 Figure 2. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1 2 3 4 5 6 7 8 Mnemonic RO RE DE DI 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. Driver Output Enable. A high level enables the driver differential inputs A and B. A low level places it in a high impedance state. 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/Driver Output A. Inverting Receiver Input B/Driver Output B. 5 V Power Supply. Rev. 0 | Page 6 of 16 ADM483 TEST CIRCUITS VCC R VOD 05079-003 A 0V OR 3V DE DE IN S1 B CL RL VOUT S2 05079-006 R VOC Figure 3. Driver Voltage Measurement Figure 6. Driver Enable/Disable 375 VOD3 05079-004 60 VTST A 05079-007 B RE VOUT CL 375 Figure 4. Driver Voltage Measurement over Common-Mode Voltage Range Figure 7. Receiver Propagation Delay +1.5V VCC S1 A RLDIFF B CL1 05079-005 -1.5V RE CL RE IN RL VOUT S2 05079-008 CL2 Figure 5. Driver Propagation Delay Figure 8. Receiver Enable/Disable Rev. 0 | Page 7 of 16 ADM483 SWITCHING CHARACTERISTICS 3V 1.5V 0V B VO A 1.5V 3V DE 1.5V 1.5V 0V tPLH 1/2VO tPHL tZL 2.3V tLZ A, B VOL +0.5V VOL tSKEW = |tPLH -tPHL| 5V 90% POINT 10% POINT 90% POINT tZH A, B 2.3V tHZ VOH 05079-011 05079-012 VOH -0.5V 0V 0V 10% POINT tR tF 05079-009 Figure 11. Driver Enable/Disable Timing Figure 9. Driver Propagation Delay, Rise/Fall Timing 3V RE 1.5V 1.5V 0V A, B 0V 0V tZL 1.5V O/P LOW tLZ tPLH tPHL VOH R VOL +0.5V VOL tZH 05079-010 O/P HIGH 1.5V tHZ VOH VOH -0.5V RO 1.5V tSKEW = |tPLH -tPHL| 1.5V VOL R 0V Figure 10. Receiver Propagation Delay Figure 12. Receiver Enable/Disable Timing Rev. 0 | Page 8 of 16 ADM483 TYPICAL PERFORMANCE CHARACTERISTICS 400 350 0.35 0.40 UNLOADED SUPPLY CURRENT (A) 300 250 200 150 100 05079-013 OUTPUT LOW VOLTAGE (V) 0.30 DE = VCC 0.25 0.20 05079-016 50 0 -50 -25 0 DE = GND 25 50 75 TEMPERATURE (C) 100 125 0.15 -50 -25 0 25 50 TEMPERATURE (C) 75 100 125 Figure 13. Supply Current vs. Temperature 50 45 RECEIVER OUTPUT CURRENT (mA) Figure 16. Receiver Output Low Voltage vs. Temperature 4.6 40 35 30 25 20 15 10 05079-014 4.5 OUTPUT HIGH VOLTAGE (V) 4.4 4.3 4.2 4.1 05079-017 5 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 RECEIVER OUTPUT LOW VOLTAGE (V) 1.8 2.0 4.0 -50 -25 0 25 50 TEMPERATURE (C) 75 100 125 Figure 14. Output Current vs. Receiver Output Low Voltage Figure 17. Receiver Output High Voltage vs. Temperature 90 RECEIVER OUTPUT CURRENT (mA) 5 DRIVER OUTPUT CURRENT (mA) 05079-015 80 70 60 50 40 30 20 10 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 DIFFERENTIAL OUTPUT VOLTAGE (V) 4.5 05079-018 0 -5 -10 -15 -20 3.5 4.0 4.5 5.0 RECEIVER OUTPUT HIGH VOLTAGE (V) 5.5 5.0 Figure 15. Output Current vs. Receiver Output High Voltage Figure 18. Driver Output Current vs. Differential Output Voltage Rev. 0 | Page 9 of 16 ADM483 120 800 700 100 PROPAGATION DELAY (ns) OUTPUT CURRENT (mA) 600 500 400 300 200 05079-022 80 60 40 20 05079-019 100 0 -50 -25 0 25 50 75 TEMPERATURE (C) 100 125 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V) 4.0 4.5 5.0 Figure 19. Output Current vs. Driver Output Low Voltage Figure 22. Receiver Propagation Delay vs. Temperature -10 OUTPUT CURRENT (mA) -30 3 -50 -70 -90 05079-020 4 -110 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V) 4.0 4.5 5.0 CH1 1.00VBW CH3 2.00VBW CH2 1.00VBW CH4 5.00V M 400ns CH3 2.00V Figure 20. Output Current vs. Driver Output High Voltage Figure 23. Driver/Receiver Propagation Delay 450 400 PROPAGATION DELAY (ns) 350 300 250 200 150 100 50 0 -50 -25 0 25 50 75 TEMPERATURE (C) 100 125 05079-021 Figure 21. Driver Propagation Delay vs. Temperature Rev. 0 | Page 10 of 16 05079-023 2 ADM483 APPLICATIONS 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 that appear as commonmode voltages on the line. There are two main standards approved by the Electronics Industries Association (EIA), which specify the electrical characteristics of transceivers used in differential data transmission. The 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. To achieve true multipoint communications, the RS-485 standard was defined. This standard meets or exceeds all the requirements of RS-422, but also allows up to 32 drivers and 32 receivers to be connected to a single bus. An extended commonmode range of -7 V to +12 V is defined. The most significant difference between RS-422 and RS-485 is that the drivers may be disabled, allowing up to 32 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 5. 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 Drivers/Receivers per Line RS-422 Differential 4000 ft. 2 V 100 4 k min 200 mV -7 V to +7 V 1/10 RS-485 Differential 4000 ft. 1.5 V 54 12 k min 200 mV -7 V to +12 V 32/32 CABLE AND DATA RATE The preferred transmission line for RS-485 communications is a twisted pair. Twisted pair cable tends to cancel commonmode noise and the magnetic fields generated by the current flowing through each wire, thereby reducing the effective inductance of the pair. The ADM483 is designed for bidirectional data communications on multipoint transmission lines. A typical application showing a multipoint transmission network is shown in Figure 24. An RS-485 transmission line can have as many as 32 transceivers on the bus. Only one driver can transmit at a particular time, but multiple receivers can be enabled simultaneously. As with any transmission line, it is important to minimize reflections. This can be done by terminating the extreme ends of the line by 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. ADM483 RO RE DE DI D B B R A A ADM483 R RO RE DE D DI A B A B ADM483 ADM483 R D R D RO RE DE DI RO RE DE DI MAXIMUM NUMBER OF TRANSCEIVERS ON BUS: 32 Figure 24. Typical Half-Duplex RS-485 Network Topology Rev. 0 | Page 11 of 16 05079-024 ADM483 THERMAL SHUTDOWN The ADM483 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 and disables the driver outputs. The thermal sensing 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 140C. RECEIVER OPEN-CIRCUIT FAIL-SAFE The receiver input includes a fail-safe feature that guarantees a logic high on the receiver when the inputs are open circuit or floating. Rev. 0 | Page 12 of 16 ADM483 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 5 4 4.00 (0.1574) 3.80 (0.1497) 1 6.20 (0.2440) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 1.75 (0.0688) 1.35 (0.0532) 0.50 (0.0196) x 45 0.25 (0.0099) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012AA 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 25. 8-Lead Standard Small Outline Package [SOIC] (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model ADM483AR ADM483AR-REEL ADM483AR-REEL7 ADM483JR ADM483JR-REEL ADM483JR-REEL7 Temperature Range -40C to +85C -40C to +85C -40C to +85C 0C to 70C 0C to 70C 0C to 70C Package Description 8-Lead Standard Small Outline Package 8-Lead Standard Small Outline Package 8-Lead Standard Small Outline Package 8-Lead Standard Small Outline Package 8-Lead Standard Small Outline Package 8-Lead Standard Small Outline Package Package Option R-8 R-8 R-8 R-8 R-8 R-8 Rev. 0 | Page 13 of 16 ADM483 NOTES Rev. 0 | Page 14 of 16 ADM483 NOTES Rev. 0 | Page 15 of 16 ADM483 NOTES (c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05079-0-10/04(0) Rev. 0 | Page 16 of 16 |
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