ADM1491E

16 Mbps, ESD Protected, Full-Duplex RS-485 Transceivers ADM1491E FEATURES RS-485/RS-422 full duplex transceiver, for high speed motor control applications 16 Mbps data rate ±8 kV ESD protection on RS-485 input/output pins Complies with ANSI/TIA/EIA-485-A-1998 Open circuit fail-safe Suitable for 5 V power supply applications 32 nodes on the bus (1 unit load) Thermal shutdown protection Operating temperature range: −40°C to +85°C Packages Narrow-body 14-lead SOIC 10-lead MSOP FUNCTIONAL BLOCK DIAGRAM VCC ADM1491E A RO RE DE Z DI D 07430-002 R B Y GND Figure 1. APPLICATIONS RS-485/RS-422 interfaces Industrial field networks High data rate motor control Multipoint data transmission systems Single-ended to differential signal conversion GENERAL DESCRIPTION The ADM1491E is an RS-485 transceiver with ±8 kV ESD protection and is suitable for high speed, full-duplex communication on multipoint transmission lines. In particular, the ADM1491E is designed for use in motor control applications requiring communications at data rates up to 16 Mbps. The ADM1491E is designed for balanced transmission lines and complies with TIA/EIA-485-A-98. The device has a 12 kΩ receiver input impedance for unit load RS-485 operation allowing up to 32 nodes on the bus. The differential transmitter outputs and receiver inputs feature electrostatic discharge circuitry that provides protection to ±8 kV using the human body model (HBM). The ADM1491E 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 ±250 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. The receiver of the ADM1491E contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating). The ADM1491E features extremely fast and closely matched switching times. Minimal driver propagation delays permit transmission at data rates up to 16 Mbps while low skew minimizes EMI interference. The ADM1491E is fully specified over the commercial and industrial temperature ranges and is available in two packages: a narrow-body 14-lead SOIC and a 10-lead MSOP. 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 ©2008 Analog Devices, Inc. All rights reserved. ADM1491E TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Timing Specifications .................................................................. 4 Absolute Maximum Ratings............................................................ 5 Thermal Resistance ...................................................................... 5 ESD Caution .................................................................................. 5 Pin Configurations and Function Descriptions ........................... 6 Typical Performance Characteristics ..............................................7 Test Circuits ........................................................................................9 Theory of Operation ...................................................................... 10 Truth Tables................................................................................. 10 ESD Transient Protection Scheme ........................................... 10 Applications Information .............................................................. 12 Differential Data ......................................................................... 12 Cable and Data Rate ................................................................... 12 Typical Applications ................................................................... 12 Outline Dimensions ....................................................................... 13 Ordering Guide .......................................................................... 13 REVISION HISTORY 12/08—Revision 0: Initial Version Rev. 0 | Page 2 of 16 ADM1491E SPECIFICATIONS 4.75 V ≤ VCC ≤ 5.25 V; all minimum/maximum specifications apply over the entire recommended operation range, unless otherwise noted. All typical specifications are at TA = 25°C, VCC = 5.0 V, unless otherwise noted. Table 1. Parameter SUPPLY CURRENT Outputs Enabled Outputs Disabled DRIVER Differential Outputs Differential Output Voltage, Loaded Symbol ICC1 ICC2 Min Typ 1.2 0.8 Max 2.0 1.5 Unit mA mA Test Conditions Outputs unloaded, digital inputs = VCC or GND Outputs unloaded, digital inputs = VCC or GND |VOD2| |VOD3| ∆|VOD2| VOC ∆|VOC| IO IO IOS VIL VIH II 2.0 1.5 1.5 ∆|VOD| for Complementary Output States Common-Mode Output Voltage ∆|VOC| for Complementary Output States Output Leakage Current (Y, Z) Output Short-Circuit Current Logic Inputs DE, RE, DI Input Low Voltage Input High Voltage 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 Three-State Output Leakage Current 5.0 5.0 5.0 0.2 3.0 0.2 100 250 0.8 −100 V V V V V V μA μA mA V V μA RL = 100 Ω (RS-422), see Figure 19 RL = 54 Ω (RS-485), see Figure 19 −7 V ≤ VTEST ≤ +12 V, see Figure 20 RL = 54 Ω or 100 Ω, see Figure 19 RL = 54 Ω or 100 Ω, see Figure 19 RL = 54 Ω or 100 Ω, see Figure 19 DE = 0 V, VDD = 0 V or 5 V, VIN = 12 V DE = 0 V, VDD = 0 V or 5 V, VIN = −7 V −7 V < VOUT < +12 V DE, RE, DI DE, RE, DI DE, RE, DI 2.0 −1 +1 VTH VHYS II RIN VOL VOH IOZR −0.2 30 +0.2 1.0 −0.8 12 30 0.4 V mV mA mA kΩ V V mA μA −7 V < VCM < +12 V VCM = 0 V VCM = 12 V VCM = −7 V −7 V ≤ VCM ≤ +12 V IOUT = +4.0 mA, VA − VB = −0.2 V IOUT = −4.0 mA, VA − VB = +0.2 V VCC = 5.25 V, 0.4 V < VOUT < 2.4 V 4.0 85 ±1 Rev. 0 | Page 3 of 16 ADM1491E TIMING SPECIFICATIONS TA = −40°C to +85°C. Table 2. Parameter DRIVER Maximum Data Rate Propagation Delay Driver Output Skew Rise Time/Fall Time Enable Time Disable Time RECEIVER Propagation Delay Skew |tPLH − tPHL| Enable Time Disable Time Symbol Min 16 tDPLH, tDPHL tSKEW tDR, tDF tZH, tZL tHZ, tLZ tPLH, tPHL tSKEW tZH, tZL tHZ, tLZ 11 0.5 8 17 2 15 20 20 20 2 13 13 Typ Max Unit Mbps ns ns ns ns ns ns ns ns ns Test Conditions RL = 54 Ω, CL = 100 pF, see Figure 21 and Figure 2 RL = 54 Ω, CL = 100 pF, see Figure 21 and Figure 2, tSKEW = |tDPLH − tDPHL| RL = 54 Ω, CL = 100 pF, see Figure 21 and Figure 2 RL = 110 Ω, CL = 50 pF, see Figure 22 and Figure 4 RL = 110 Ω, CL = 50 pF, see Figure 22 and Figure 4 CL = 15 pF, see Figure 23 and Figure 3 CL = 15 pF, see Figure 23 and Figure 3 RL = 1 kΩ, CL = 15 pF, see Figure 24 and Figure 5 RL = 1 kΩ, CL = 15 pF, see Figure 24 and Figure 5 12 0.4 Timing Diagrams Switching Characteristics VCC VCC/2 0V VCC/2 VCC DE 0.5VCC 0.5VCC 0V tDPLH Z 1/2VO VO tDPHL tZL 2.3V tLZ Y, Z VOL + 0.5V VOL Y tZH Y, Z 2.3V tHZ VOH 07430-011 VOH – 0.5V 0V +VO VDIFF –VO 90% POINT VDIFF = V(Y) – V(Z) 90% POINT 10% POINT 10% POINT tDR tDF 07430-009 Figure 2. Driver Propagation Delay Rise/Fall Timing Figure 4. Driver Enable/Disable Timing 0.7VCC A–B 0V 0V RE 0.5VCC 0.5VCC 0.3VCC tPLH tPHL VOH RO tZL 1.5V OUTPUT LOW tLZ VOL + 0.5V VOL RO 1.5V 07430-010 tSKEW = |tPLH – tPHL| 1.5V VOL tZH OUTPUT HIGH RO 0V 1.5V tHZ VOH 07430-012 VOH – 0.5V Figure 3. Receiver Propagation Delay Timing Figure 5. Receiver Enable/Disable Timing Rev. 0 | Page 4 of 16 ADM1491E ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 3. Parameter VCC to GND Digital I/O Voltage (DE, RE) Driver Input Voltage (DI) Receiver Output Voltage (RO) Driver Output/Receiver Input Voltage (A, B, Y, Z) Operating Temperature Range Storage Temperature Range ESD (HBM) on A, B, Y, and Z Rating −0.3 V to +7 V −0.3 V to VCC + 0.3 V −0.3 V to VCC + 0.3 V −0.3 V to VCC + 0.3 V −9 V to +14 V −40°C to +85°C −55°C to +150°C ±8 kV THERMAL RESISTANCE θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 4. Thermal Resistance Package Type 14-Lead SOIC 10-Lead MSOP θJA 104.5 133 θJC 87.2 Unit °C/W °C/W ESD CAUTION 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. Rev. 0 | Page 5 of 16 ADM1491E PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS ADM1491E NC 1 RO 2 RE 3 DE 4 GND 6 GND 7 14 VCC 13 VCC 12 A ADM1491E RO 1 RE 2 DE 3 DI 4 GND 5 TOP VIEW (Not to Scale) 10 VCC 9 8 7 6 A B 07430-015 TOP VIEW 11 B (Not to Scale) 10 Z DI 5 9 8 Z Y Y 07430-013 NC NC = NO CONNECT Figure 6. 14-Lead Narrow-Body SOIC Pin Configuration Figure 7. 10-Lead MSOP Pin Configuration Table 5. Pin Function Descriptions Pin No. 14-Lead SOIC 10-Lead MSOP 1 N/A 1 2 1 3 2 4 5 6 7 8 9 10 11 12 13 14 1 Mnemonic NC RO RE DE DI GND GND NC Y Z B A VCC VCC 3 4 5 N/A1 N/A1 6 7 8 9 10 N/A1 Description No Connect. This pin is available on the 14-lead SOIC only. Receiver Output. Receiver Output Enable. A low level enables the receiver output, whereas a high level places the receiver output in a high impedance state. Driver Output Enable. A high level enables the differential driver outputs, A and B, whereas a low places the differential driver outputs in a high impedance state. Driver Input. When the driver is enabled, a logic low on DI forces A low and B high, whereas logic high on DI forces A high and B low. Ground. Ground. This pin is available on the 14-lead SOIC only. No Connect. This pin is available on the 14-lead SOIC only. Noninverting Driver Output Y. Inverting Driver Output Z. Inverting Receiver Input B. Noninverting Receiver Input A. Power Supply (5 V ± 5%). Power Supply (5 V ± 5%). This pin is available on the 14-lead SOIC only. N/A indicates not applicable to the MSOP. Rev. 0 | Page 6 of 16 ADM1491E TYPICAL PERFORMANCE CHARACTERISTICS 35 0.50 0.45 30 OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 25 0.40 0.35 0.30 0.25 0.20 20 15 10 5 07430-016 0 0 0.25 0.50 0.75 1.00 1.25 OUTPUT VOLTAGE (V) 1.50 1.75 2.00 0.15 –50 –25 0 25 TEMPERATURE (°C) 50 75 85 Figure 8. Output Current vs. Receiver Output Low Voltage 0 Figure 11. Receiver Output Low Voltage vs. Temperature (IOUT = 8 mA) 80 70 –5 60 OUTPUT CURRENT (mA) –10 OUTPUT CURRENT (mA) 50 40 30 20 10 –15 –20 –25 0 3.75 4.00 4.25 4.50 OUTPUT VOLTAGE (V) 4.75 5.00 07430-017 0 0.5 1.0 1.5 2.0 2.5 3.0 OUTPUT VOLTAGE (V) 3.5 4.0 4.5 Figure 9. Output Current vs. Receiver Output High Voltage 4.75 Figure 12. Output Current vs. Driver Differential Output Voltage 3.00 2.95 4.70 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 2.90 2.85 2.80 2.75 2.70 4.65 4.60 4.55 2.65 07430-018 4.50 –50 –25 0 25 TEMPERATURE (°C) 50 75 85 2.60 –50 –25 0 25 TEMPERATURE (°C) 50 75 85 Figure 10. Receiver Output High Voltage vs. Temperature (IOUT = 8 mA) Figure 13. Driver Differential Output Voltage vs. Temperature (RL = 56.3 Ω) Rev. 0 | Page 7 of 16 07430-021 07430-020 –30 3.50 –10 07430-019 ADM1491E 80 70 OUTPUT CURRENT (mA) 60 50 40 30 20 10 07430-022 1 3 07430-032 0 0 0.5 1.0 1.5 2.0 2.5 OUTPUT VOLTAGE (V) 3.0 3.5 4.0 CH1 5V CH3 2V CH2 2V M200ns A CH1 1.6V Figure 14. Output Current vs. Driver Output Low Voltage 0 –10 Figure 17. Unloaded Driver Differential Outputs OUTPUT CURRENT (mA) –20 –30 –40 –50 –60 –70 –80 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V) 4.0 4.5 5.0 07430-023 1 3 07430-033 CH1 5V CH3 2V CH2 2V M200ns A CH1 1.6V Figure 15. Output Current vs. Driver Output High Voltage 1.30 1.25 1.20 DRIVER ENABLED Figure 18. Loaded Driver Differential Outputs (RL Differential = 54 Ω, CL1 = CL2 = 100 pF) OUTPUT CURRENT (mA) 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 –50 –25 0 25 TEMPERATURE (°C) 50 75 85 07430-024 DRIVER DISABLED Figure 16. Output Current vs. Temperature Rev. 0 | Page 8 of 16 ADM1491E TEST CIRCUITS Y DI Z VOD2 RL 2 Y VOC DI 07430-003 RL 2 VOUT RL 110Ω 07430-006 VCC S1 Z CL 50pF S2 DE Figure 19. Driver Voltage Measurements Figure 22. Driver Enable/Disable Timing Y DI Z VOD3 60Ω 375Ω A 07430-004 B CL Figure 20. Driver Voltage Measurements Figure 23. Receiver Propagation Delay +1.5V 07430-007 375Ω V TEST RE VOUT VCC S1 RL RE S2 07430-008 Y DI RL CL 07430-005 –1.5V CL VOUT Z CL RE Figure 21. Driver Propagation Delay Figure 24. Receiver Enable/Disable Timing Rev. 0 | Page 9 of 16 ADM1491E THEORY OF OPERATION The ADM1491E is an RS-485 transceiver that operates from a single 5 V ± 5% power supply. The ADM1491E is intended for balanced data transmission and complies with both TIA/EIA-485-A and TIA/EIA-422-B. It contains a differential line driver and a differential line receiver and is suitable for full-duplex data transmission. The input impedance of the ADM1491E is 12 kΩ, allowing up to 32 transceivers on the differential bus. A thermal shutdown circuit prevents excessive power dissipation caused by bus contention or by output shorting. This feature forces the driver output into a high impedance state if, during fault conditions, a significant temperature increase is detected in the internal driver circuitry. The receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating). The ADM1491E features very low propagation delay, ensuring maximum baud rate operation. The 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). ESD TRANSIENT PROTECTION SCHEME The ADM1491E uses protective clamping structures on its inputs and outputs to clamp the voltage to a safe level and dissipate the energy present in ESD (electrostatic). The protection structure achieves ESD protection up to ±8 kV human body model (HBM). ESD Testing Two coupling methods are used for ESD testing: contact discharge and air gap discharge. Contact discharge calls for a direct connection to the unit being tested; air gap discharge uses a higher test voltage but does not make direct contact with the unit under test. With air discharge, the discharge gun is moved toward the unit under test, developing an arc across the air gap; hence the term air discharge. This method is influenced by humidity, temperature, barometric pressure, distance, and rate of closure of the discharge gun. The contact discharge method, though less realistic, is more repeatable and is gaining acceptance and preference over the air gap method. Although very little energy is contained within an ESD pulse, the extremely fast rise time, coupled with high voltages, can cause failures in unprotected semiconductors. Catastrophic destruction can occur immediately because of arcing or heating. Even if catastrophic failure does not occur immediately, the device can suffer from parametric degradation, resulting in degraded performance. The cumulative effects of continuous exposure can eventually lead to complete failure. HIGH VOLTAGE GENERATOR C1 R2 DEVICE UNDER TEST TRUTH TABLES Table 6. Truth Table Abbreviations Letter H I L X Z Description High level Indeterminate Low level Irrelevant High impedance (off ) Table 7. Transmitting DE H H L Inputs DI H L X Z L H Z Outputs Y H L Z NOTES 1. THE ESD TEST METHOD USED IS THE HUMAN BODY MODEL (±8kV) WITH R2 = 1500Ω AND C1 = 100pF. Figure 25. ESD Generator Table 8. Receiving RE L L L L H Inputs A−B ≥ +0.2 V ≤ −0.2 V −0.2 V ≤ A − B ≤ +0.2 V Inputs open X Output RO H L I H Z I/O lines are particularly vulnerable to ESD damage. Simply touching or plugging in an I/O cable can result in a static discharge that can damage or destroy the interface product connected to the I/O port. It is, therefore, extremely important to have high levels of ESD protection on the I/O lines. The ESD discharge can induce latch-up in the device under test. Therefore, it is important to conduct ESD testing on the I/O pins while device power is applied. This type of testing is more representative of a real-world I/O discharge where the equipment is operating normally when the discharge occurs. Rev. 0 | Page 10 of 16 07430-025 ADM1491E 100% 90% IPEAK 36.8% 10% 07430-026 tRL tDL TIME (t) Figure 26. Human Body Model ESD Current Waveform Table 9. ADM1491E ESD Test Results ESD Test Method Human Body Model Input/Output Pins ±8 kV Other Pins ±1.5 kV Rev. 0 | Page 11 of 16 ADM1491E APPLICATIONS INFORMATION DIFFERENTIAL DATA Differential data transmission reliably transmits 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 of up to 10 MBaud and line lengths of up to 4000 feet. A single driver can drive a transmission line with as many as 10 receivers. The RS-485 standard addresses true multipoint communications. This standard meets or exceeds all of the requirements of RS-422, and it allows as many as 32 drivers and 32 receivers to connect to a single bus. An extended common-mode 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; as many as 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. MASTER A RO RE DE DI D Z Y B R B Y 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. 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. Keep stub lengths of the main line as short as possible. A properly terminated transmission line appears purely resistive to the driver. TYPICAL APPLICATIONS Figure 27 shows a typical configuration for a full-duplex multipoint application using the ADM1491E. To minimize reflections, the lines must be terminated at the receiving end in its characteristic impedance, and stub lengths off the main line must be kept as short as possible. MAXIMUM NUMBER OF NODES = 32 SLAVE RT D Z DI DE RE RT A R RO ADM1491E A SLAVE B Z Y A B Z Y SLAVE ADM1491E ADM1491E R D R D ADM1491E NOTES 1. RT IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE. Figure 27. Typical Application Rev. 0 | Page 12 of 16 07430-028 RO RE DE DI RO RE DE DI ADM1491E OUTLINE DIMENSIONS 8.75 (0.3445) 8.55 (0.3366) 14 1 8 7 4.00 (0.1575) 3.80 (0.1496) 6.20 (0.2441) 5.80 (0.2283) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 0.51 (0.0201) 0.31 (0.0122) 1.75 (0.0689) 1.35 (0.0531) SEATING PLANE 0.50 (0.0197) 0.25 (0.0098) 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 45° COMPLIANT TO JEDEC STANDARDS MS-012-AB 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 Standard Small Outline Package [SOIC_N] Narrow Body (R-14) Dimensions shown in millimeters and (inches) 3.10 3.00 2.90 3.10 3.00 2.90 PIN 1 0.50 BSC 0.95 0.85 0.75 0.15 0.05 0.33 0.17 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-BA 1.10 MAX 8° 0° 0.80 0.60 0.40 10 6 5.15 4.90 4.65 1 5 SEATING PLANE 0.23 0.08 Figure 29. 10-Lead Mini Small Outline Package [MSOP] (RM-10) Dimensions shown in millimeters ORDERING GUIDE Model ADM1491EBRZ 1 ADM1491EBRZ-REEL71 ADM1491EBRMZ1 ADM1491EBRMZ-REEL71 1 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C 060606-A Package Description 14-Lead Standard Small Outline Package, Narrow Body [SOIC_N] 14-Lead Standard Small Outline Package, Narrow Body [SOIC_N] 10-Lead Mini Small Outline Package [MSOP] 10-Lead Mini Small Outline Package [MSOP] Package Option R-14 R-14 RM-10 RM-10 Branding F0D F0D Z = RoHS Compliant Part. Rev. 0 | Page 13 of 16 ADM1491E NOTES Rev. 0 | Page 14 of 16 ADM1491E NOTES Rev. 0 | Page 15 of 16 ADM1491E NOTES ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07430-0-12/08(0) Rev. 0 | Page 16 of 16