5 V, 0.8 mA PROFIBUS RS-485 Transceiver ADM1486 Meets and exceeds EIA RS-485 and EIA RS-422 standards 30 Mbps data rate Recommended for PROFIBUS applications 2.1 V minimum differential output with 54 Ω termination Low power 0.8 mA ICC Thermal shutdown and short-circuit protection 0.5 ns skew driver and receiver Driver propagation delay: 11 ns Receiver propagation delay: 12 ns High impedance outputs with drivers disabled or power off Superior upgrade for SN65ALS1176 Available in standard 8-lead SOIC package APPLICATIONS FUNCTIONAL BLOCK DIAGRAM ADM1486 8 VCC 2 7 B DE 3 6 A DI 4 5 GND RO 1 RE R D 02603-001 FEATURES Figure 1. Industrial field equipment GENERAL DESCRIPTION The ADM1486 is a differential line transceiver suitable for high speed bidirectional data communication on multipoint bus transmission lines. It is designed for balanced data transmission, complies with EIA Standards RS-485 and RS-422, and is recommended for PROFIBUS applications. The part contains a differential line driver and a differential line receiver. Both the driver and the receiver may be enabled independently. When disabled or powered down, the driver outputs are high impedance. The ADM1486 operates from a single 5 V power supply. Excessive power dissipation caused by bus contention or output shorting is prevented by short-circuit protection and thermal circuitry. Short-circuit protection circuits limit the maximum output current to ±200 mA during fault conditions. A thermal shutdown circuit senses if the die temperature rises above 150°C and forces the driver outputs into a high impedance state under this condition. Up to 50 transceivers may be connected simultaneously on a bus, but only one driver should be enabled at a time. Therefore, it is important that the remaining disabled drivers do not load the bus. To ensure this, the ADM1486 driver features high output impedance when disabled and when powered down. This minimizes the loading effect when the transceiver is not being used. The 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 ADM1486 is fabricated on BiCMOS, an advanced mixed technology process combining low power CMOS with fast switching bipolar technology. All inputs and outputs contain protection against ESD; all driver outputs feature high source and sink current capability. An epitaxial layer is used to guard against latch-up. The ADM1486 features extremely fast and closely matched switching, enable, and disable times. Minimal driver propagation delays permit transmission at data rates up to 30 Mbps while low skew minimizes EMI interference. The part is fully specified over the commercial and industrial temperature range and is available in an 8-lead SOIC 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: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved. ADM1486 TABLE OF CONTENTS Specifications..................................................................................... 3 Applications Information .............................................................. 13 Timing Specifications....................................................................... 4 Differential Data Transmission ................................................ 13 Absolute Maximum Ratings............................................................ 5 Cable and Data Rate................................................................... 13 ESD Caution.................................................................................. 5 Thermal Shutdown .................................................................... 13 Pin Configuration and Function Descriptions............................. 6 Propagation Delay ...................................................................... 13 Test Circuits....................................................................................... 7 Receiver Open-Circuit Fail-Safe............................................... 13 Switching Characteristics ................................................................ 8 Outline Dimensions ....................................................................... 15 Typical Performance Characteristics ............................................. 9 Ordering Guide .......................................................................... 15 REVISION HISTORY 3/05—Rev. 0 to Rev. A Updated Format..................................................................Universal Added PROFIBUS Logo .................................................................. 1 Updated Outline Dimensions ....................................................... 15 Changes to Ordering Guide .......................................................... 15 11/02—Revision 0: Initial Version Rev. A | Page 2 of 16 ADM1486 SPECIFICATIONS VCC = 5 V ±5%. All specifications TMIN to TMAX, unless otherwise noted. Table 1. Parameter DRIVER Differential Output Voltage, VOD VOD3 ∆| 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) CMOS Input Logic Threshold Low, VINL CMOS Input Logic Threshold High, VINH Logic Input Current (DE, DI) RECEIVER Differential Input Threshold Voltage, VTH Input Voltage Hysteresis, ∆VTH Input Resistance Input Current (A, B) Logic Enable Input Current (RE) CMOS Output Voltage Low, VOL CMOS Output Voltage High, VOH Short-Circuit Output Current Three-State Output Leakage Current POWER SUPPLY CURRENT ICC (Outputs Enabled) ICC (Outputs Disabled) Min Typ 2.1 2.1 2.1 60 60 Max Unit Test Conditions/Comments 5.0 5.0 5.0 5.0 0.2 3.0 0.2 200 200 0.8 V V V V V V V mA mA V V µA R = Infinity, see Figure 3 VCC = 5 V, R = 50 Ω (RS-422), see Figure 3 R = 27 Ω (RS-485), see Figure 3 VTST = −7 V to +12 V, see Figure 4 R = 27 Ω or 50 Ω, see Figure 3 R = 27 Ω or 50 Ω, see Figure 3 R = 27 Ω or 50 Ω −7 V ≤ VO ≤ +12 V −7 V ≤ VO ≤ +12 V −7 V ≤ VCM ≤ +12 V VCM = 0 V −7 V ≤ VCM ≤ +12 V VIN = +12 V VIN = −7 V 85 ±1.0 V mV kΩ mA mA µA V V mA µA IOUT = +4.0 mA IOUT = −4.0 mA VOUT = GND or VCC 0.4 V ≤ VOUT ≤ 2.4 V 2.0 1.5 mA mA Outputs unloaded, digital inputs = GND or VCC Outputs unloaded, digital inputs = GND or VCC 2.0 ±1.0 −0.2 20 +0.2 70 30 0.6 −0.35 ±1.0 0.4 4.0 7 1.2 0.8 Rev. A | Page 3 of 16 ADM1486 TIMING SPECIFICATIONS VCC = 5 V ±5%. All specifications TMIN to TMAX, unless otherwise noted. Table 2. Parameter DRIVER Propagation Delay Input to Output tPLH, tPHL Driver O/P to O/P tSKEW Driver Rise/Fall Time tR, tF Driver Enable to Output Valid tZH, tZL Driver Disable Timing tHZ, tLZ Matched Enable Switching | tAZH − tBZL |, | tBZH − tAZL | Matched Disable Switching | tAHZ − tBLZ |, | tBHZ − tALZ | RECEIVER Propagation Delay Input to Output tPLH, tPHL Skew | tPLH − tPHL | Receiver Enable tZH, tZL Receiver Disable tHZ, tLZ 1 Min Typ Max Unit Test Conditions/Comments 4 11 11 0.5 8 9 9 17 13 2 15 15 15 ns ns ns ns ns ns RLDIFF = 54 Ω, CL1 = CL2 = 100 pF, see Figure 5 RLDIFF = 54 Ω, CL1 = CL2 = 100 pF @ TA = 25°C RLDIFF = 54 Ω, CL1 = CL2 = 100 pF, see Figure 51 RLDIFF = 54 Ω, CL1 = CL2 = 100 pF, see Figure 5 RL = 110 Ω, CL = 50 pF, see Figure 6 RL = 110 Ω, CL = 50 pF, see Figure 6 1 3 ns RL = 110 Ω, CL = 50 pF, see Figure 6 2 5 ns RL = 110 Ω, CL = 50 pF, see Figure 6 12 0.4 7 7 20 2 13 13 ns ns ns ns CL = 15 pF, see Figure 7 CL = 15 pF1, see Figure 7 CL = 15 pF, RL = 1 kΩ, see Figure 8 CL = 15 pF, RL = 1 kΩ, see Figure 8 6 Guaranteed by characterization. Rev. A | Page 4 of 16 ADM1486 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 3. Parameter VCC Inputs Driver Input (DI) Control Inputs (DE, RE) Receiver Inputs (A, B) Outputs Driver Outputs Receiver Outputs Power Dissipation 8-Lead SOIC θJA, Thermal Impedance Operating Temperature Range Industrial (A Version) Storage Temperature Range Lead Temperature (Soldering, 10 sec) Vapor Phase (60 sec) Infrared (15 sec) Rating 7V −0.3 V to VCC + 0.3 V −0.3 V to VCC + 0.3 V −9 V to +14 V 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 in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect device reliability. −9 V to +14 V −0.5 V to VCC + 0.5 V 450 mW 170°C/W −40°C to +85°C −65°C to +150°C 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. A | Page 5 of 16 ADM1486 RO 1 RE 2 ADM1486 8 VCC 7 B DE 3 6 A TOP VIEW DI 4 (Not to Scale) 5 GND 02603-002 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Figure 2. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1 2 Mnemonic RO RE 3 DE 4 DI 5 6 7 8 GND A B VCC Description Receiver Output. When enabled, if A > B by 200 mV, RO = high. If A < B by 200 mV, 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 outputs, 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 Connection, 0 V. Noninverting Receiver Input A/Driver Output A. Inverting Receiver Input B/Driver Output B. Power Supply, 5 V ±5%. Table 5. Transmitting DE Input 1 1 0 DI Input 1 0 X B Output 0 1 Z A Output 1 0 Z Table 6. Receiving RE A–B Input RO Output 0 0 0 1 ≥ +0.2 V ≤ −0.2 V Inputs open X 1 0 1 Z Rev. A | Page 6 of 16 ADM1486 TEST CIRCUITS A VCC A VOD S2 VOUT CL DE 02603-003 VOC B RL S1 0V OR 3V R 02603-006 R B DE IN Figure 6. Driver Enable/Disable Figure 3. Driver Voltage Measurement 375Ω A A VTST B CL 02603-004 B VOUT RE 375Ω Figure 4. Driver Voltage Measurement Figure 7. Receiver Propagation Delay +1.5V A CL1 RLDIFF B RL –1.5V 02603-005 CL2 VCC S1 RE CL VOUT RE IN Figure 8. Receiver Enable/Disable Figure 5. Driver Propagation Delay Rev. A | Page 7 of 16 S2 02603-008 60Ω 02603-07 VOD3 ADM1486 SWITCHING CHARACTERISTICS 3V 1.5V 1.5V 0V tPLH tPHL B 1/2VO A–B VO 0V 0V tPLH tPHL A tSKEW = |tPLH – tPHL| tR 1.5V tSKEW = |tPLH – tPHL| 02603-009 –VO 1.5V 10% POINT 10% POINT tF VOL Figure 11. Receiver Propagation Delay Figure 9. Driver Propagation Delay, Rise/Fall Timing 3V 3V DE 1.5V 1.5V RE 1.5V 1.5V 0V 0V tZL tLZ 2.3V A, B tLZ tZL 1.5V RO VOL +0.5V O/P HIGH VOH 2.3V 0V VOH 02603-010 A, B VOL tHZ tZH VOH –0.5V VOL +0.5V O/P LOW VOL tHZ tZH 02603-011 RO 0V RO 1.5V VOH –0.5V 0V Figure 12. Receiver Enable/Disable Timing Figure 10. Driver Enable/Disable Timing Rev. A | Page 8 of 16 02603-012 VO VOH 90% POINT 90% POINT ADM1486 35 0.50 30 0.45 OUTPUT VOLTAGE (V) 25 20 15 10 0 0 0.25 0.50 0.75 1.00 1.25 OUTPUT VOLTAGE (V) 1.50 1.75 0.35 0.30 0.25 0.20 02603-013 5 0.40 0.15 –50 2.00 Figure 13. Output Current vs. Receiver Output Low Voltage 02603-016 OUTPUT CURRENT (mA) TYPICAL PERFORMANCE CHARACTERISTICS –25 0 25 50 TEMPERATURE (°C) 75 100 125 Figure 16. Receiver Output Low Voltage vs. Temperature (I = 8 mA) 0 80 70 60 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) –5 –10 –15 –20 50 40 30 20 10 3.75 4.00 4.25 4.50 OUTPUT VOLTAGE (V) 4.75 02603-017 –30 3.50 02603-014 –25 0 –10 5.00 0 Figure 14. Output Current vs. Receiver Output High Voltage 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT VOLTAGE (V) 3.5 4.0 4.5 Figure 17. Output Current vs. Driver Differential Output Voltage 4.75 3.00 2.95 OUTPUT VOLTAGE (V) 4.65 4.60 2.90 2.85 2.80 2.75 2.70 4.55 –25 0 25 50 TEMPERATURE (°C) 75 100 2.60 –50 125 Figure 15. Receiver Output High Voltage vs. Temperature (I = 8 mA) 02603-018 4.50 –50 2.65 02603-015 OUTPUT VOLTAGE (V) 4.70 –25 0 25 50 TEMPERATURE (°C) 75 100 125 Figure 18. Driver Differential Output Voltage vs. Temperature (RLDIFF = 53.6 Ω) Rev. A | Page 9 of 16 1.4 70 1.3 60 1.2 50 1.1 40 1.0 30 0.9 20 0.8 10 0.7 0 0 0.5 1.0 1.5 2.0 2.5 OUTPUT VOLTAGE (V) 3.0 3.5 0.6 –50 4.0 Figure 19. Output Current vs. Driver Output Low Voltage 02603-022 TIME (ns) 90 02603-019 OUTPUT CURRENT (mA) ADM1486 –25 0 25 50 TEMPERATURE (°C) 75 100 125 Figure 22. Receiver Skew vs. Temperature 0 5.0 4.5 –10 3.5 –30 TIME (ns) OUTPUT CURRENT (mA) 4.0 –20 –40 –50 |TPHLA–TPHLB| 3.0 2.5 |TPLHA–TPLHB| 2.0 1.5 –60 1.0 –80 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V) 4.0 4.5 0.5 0 –75 5.0 Figure 20. Output Current vs. Driver Output High Voltage –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 150 125 150 Figure 23. Driver Skew vs. Temperature 1.30 1.0 1.25 0.9 1.20 0.8 DRIVER ENABLED 0.7 1.10 0.6 PWD 1.15 1.05 0.5 1.00 0.4 0.95 0.3 –25 0 25 50 TEMPERATURE (°C) 75 100 125 Figure 21. Supply Current vs. Temperature 02603-024 DRIVER DISABLED 0.85 0.80 –50 |TPLH–TPHL| 0.2 0.90 02603-021 OUTPUT CURRENT (mA) CROSSPOINT A, B 02603-023 02603-020 –70 0.1 0 –75 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 Figure 24. Tx Pulse Width Distortion Rev. A | Page 10 of 16 ADM1486 A DI 3 A B B 1, 2 CH1 1.00VΩ CH2 1.00VΩ M4.00ns CH1 RO 4 1.72V CH1 CH3 Figure 25. Unloaded Driver Differential Outputs 1.00VΩ 2.00VΩ CH2 CH4 1.00VΩ 5.00VΩ M10.0ns CH1 1.72V Figure 28. Driver/Receiver Propagation Delays High to Low (RLDiff = 54 Ω, CL1 = CL2 = 100 pF) A A B B 02603-026 02603-029 1, 2 1, 2 CH1 500mVΩ CH2 500mVΩ M4.00ns CH1 CH1 1.72V 1.00VΩ CH2 1.00VΩ M10.0ns CH1 3.40V Figure 29. Unloaded Driver Outputs at 15 Mbps Figure 26. Loaded Driver Differential Output (RLDiff = 54 Ω, CL1 = CL2 = 100 pF) DI 3 A A B B 1, 2 1, 2 02603-027 02603-030 RO 4 CH1 CH3 1.00VΩ 2.00VΩ CH2 CH4 1.00VΩ 5.00VΩ M10.0ns CH1 CH1 1.72V Figure 27. Driver/Receiver Propagation Delays Low to High (RLDIFF = 54 Ω, CL1 = CL2 = 100 pF) 1.00VΩ CH2 1.00VΩ M4.00ns CH1 Figure 30. Unloaded Driver Outputs at 30 Mbps Rev. A | Page 11 of 16 3.40V 02603-028 02603-025 1, 2 ADM1486 A A B B 1, 2 CH1 1.00VΩ CH2 1.00VΩ M4.00ns CH1 02603-032 02603-031 1, 2 3.40V CH1 Figure 31. Loaded Driver Outputs at 15 Mbps (RLDIFF = 54 Ω, CL1 = CL2 = 100 pF) 1.00VΩ CH2 1.00VΩ M4.00ns CH1 Figure 32. Loaded Driver Outputs at 30 Mbps (RLDIFF = 54 Ω, CL1 = CL2 = 100 pF) Rev. A | Page 12 of 16 3.50V ADM1486 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 that appear as common-mode voltages on the line. There are two main standards approved by the Electronics Industries Association (EIA) that 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 4,000 feet. A single driver can drive a transmission line with up to 10 receivers. An RS-485 transmission line can have as many as 32 transceivers on the bus. Only one driver can transmit at a time, but multiple receivers may be enabled simultaneously. As with any transmission line, it is important to minimize reflections. 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. THERMAL SHUTDOWN In order to address true multipoint communications, the RS-485 standard was defined. This standard meets or exceeds all of the requirements of RS-422, and it allows up to 32 drivers and 32 receivers to connect to a single bus. An extended commonmode range of −7 V to +12 V is defined. The most significant difference between the RS-422 and the RS-485 is that the drivers with RS-485 can be disabled, allowing more than one driver to be connected to a single line; in fact, 32 drivers can 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. CABLE AND DATA RATE Twisted pair is the transmission line of choice for RS-485 communications. Twisted pair cable tends to cancel commonmode noise and causes cancellation of the magnetic fields generated by the current flowing through each wire, thereby reducing the effective inductance of the pair. The ADM1486 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. Thermal sensing circuitry detects the increase in die temperature and disables the driver outputs. Thermal sensing circuitry is designed to disable the driver outputs when a die temperature reaches 150°C. As the device cools, the drivers are re-enabled at 140°C. PROPAGATION DELAY The ADM1486 features very low propagation delay, ensuring maximum baud rate operation. The well-balanced driver ensures distortion-free transmission. Another important specification is a measure of the skew between the complementary outputs. Excessive skew impairs the noise immunity of the system and increases the amount of electromagnetic interference (EMI). RECEIVER OPEN-CIRCUIT FAIL-SAFE The ADM1486 is designed for bidirectional data communications on multipoint transmission lines. A typical application showing a multipoint transmission network is shown in Figure 33. The receiver input includes a fail-safe feature that guarantees a logic high on the receiver when the inputs are open circuit or floating. RT RT D D R R R R D 02603-033 D Figure 33. Typical RS-485 Network Rev. A | Page 13 of 16 ADM1486 Table 7. Comparison of RS-422, RS-485, and PROFIBUS 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 No. of Drivers/Receivers per Line RS-422 Differential 4,000 ft. ±2 V 100 Ω 4 kΩ min ±200 mV −7 V to +7 V 1/10 Rev. A | Page 14 of 16 RS-485 Differential 4,000 ft. ±1.5 V 54 Ω 12 kΩ min ±200 mV −7 V to +12 V 32/32 PROFIBUS Differential ±2.1 V 54 Ω 20 kΩ min ±200 mV −7 V to +12 V 50/50 ADM1486 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 8 5 4.00 (0.1574) 3.80 (0.1497) 1 4 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) 0.51 (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-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 34. 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model ADM1486AR ADM1486AR-REEL ADM1486AR-REEL7 ADM1486ARZ1 ADM1486ARZ-REEL1 ADM1486ARZ-REEL71 1 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Package Description 8-Lead Narrow Body (SOIC) 8-Lead Narrow Body (SOIC) 8-Lead Narrow Body (SOIC) 8-Lead Narrow Body (SOIC) 8-Lead Narrow Body (SOIC) 8-Lead Narrow Body (SOIC) Z = Pb-free part. Rev. A | Page 15 of 16 Package Option R-8 R-8 R-8 R-8 R-8 R-8 ADM1486 NOTES © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C02603-0-3/05(A) Rev. A | Page 16 of 16