Half-Duplex, iCoupler Isolated RS-485 Transceiver Data Sheet ADM2481 FEATURES FUNCTIONAL BLOCK DIAGRAM V V DD1 DD2 RS-485 transceiver with electrical data isolation Complies with ANSI TIA/EIA-485-A and ISO 8482: 1987(E) ADM2481 500 kbps data rate DE Slew rate-limited driver outputs Low power operation: 2.5 mA maximum TxD Suitable for 5 V or 3.3 V operations (V ) DD1 High common-mode transient immunity: >25 kV/s A True fail-safe receiver inputs RxD B Chatter-free power-up/power-down protection RE 256 nodes on bus Thermal shutdown protection GND GND 1 2 Safety and regulatory approvals Figure 1. UL recognition: 2500 V rms for 1 minute per UL 1577 VDE certificates of conformity DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12 V = 560 V peak IORM Operating temperature range: 40C to +85C APPLICATIONS Low power RS-485/RS-422 networks Isolated interfaces Building control networks Multipoint data transmission systems GENERAL DESCRIPTION The ADM2481 differential bus transceiver is an integrated, to form a differential input/output (I/O) port. When the driver galvanically isolated component designed for bidirectional data is disabled or when VDD1 or VDD2 = 0 V, this imposes minimal communication on balanced, multipoint bus transmission lines. loading on the bus. An active-high receiver disable feature, It complies with ANSI EIA/TIA-485-A and ISO 8482: 1987(E). which causes the receiver output to enter a high impedance Using iCoupler technology from Analog Devices, Inc., the state, is provided as well. ADM2481 combines a 3-channel isolator, a three-state diffe- The receiver inputs have a true fail-safe feature that ensures a rential line driver, and a differential input receiver into a single logic-high receiver output level when the inputs are open or package. The logic side of the device is powered with either a shorted. This guarantees that the receiver outputs are in a 5 V or 3 V supply, and the bus side uses a 5 V supply only. known state before communication begins and at the point The ADM2481 is slew-limited to reduce reflections with improp- when communication ends. erly terminated transmission lines. The controlled slew rate Current limiting and thermal shutdown features protect against limits the data rate to 500 kbps. The input impedance of the output short circuits and bus contention situations that might device is 96 k, allowing up to 256 transceivers on the bus. Its cause excessive power dissipation. The part is fully specified driver has an active-high enable feature. The driver differential over the industrial temperature range of 40C to +85C and is outputs and receiver differential inputs are connected internally available in a 16-lead, wide body SOIC package. Rev. B Document Feedback 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20102018 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. GALVANIC ISOLATION 08920-001ADM2481 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ..............................................8 Applications ....................................................................................... 1 Test Circuits ..................................................................................... 11 Functional Block Diagram .............................................................. 1 Switching Characteristics .............................................................. 12 General Description ......................................................................... 1 Circuit Description......................................................................... 13 Revision History ............................................................................... 2 Electrical Isolation ...................................................................... 13 Specifications ..................................................................................... 3 Truth Tables................................................................................. 14 Timing Specifications .................................................................. 4 Thermal Shutdown .................................................................... 14 Package Characteristics ............................................................... 4 True Fail-Safe Receiver Inputs .................................................. 14 Regulatory Information ............................................................... 4 Magnetic Field Immunity .......................................................... 14 Insulation and Safety-Related Specifications ............................ 4 Applications Information .............................................................. 16 VDE 0884 Insulation Characteristics ........................................ 5 Printed Circuit Board (PCB) Layout ....................................... 16 Absolute Maximum Ratings ............................................................ 6 Isolated Power Supply Circuit .................................................. 16 ESD Caution .................................................................................. 6 Outline Dimensions ....................................................................... 17 Pin Configuration and Function Descriptions ............................. 7 Ordering Guide .......................................................................... 17 REVISION HISTORY 4/2018Rev. A to Rev. B Change to Minimum External Air Gap (Clearance) Parameter, Value Column, Table 5 ................................................. 4 6/2012Rev. 0 to Rev. A Updated Safety and Regulatory Approvals (Throughout) .......... 1 Updated Outline Dimensions ....................................................... 17 Changes to Ordering Guide .......................................................... 17 7/2010Revision 0: Initial Version Rev. B Page 2 of 17