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ADM3485E

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.Tel: 781/329-4700World Wide Web Site: www.wendangwang.com Fax: 781/326-8703© Analog Devices, Inc., 2000

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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

ESD Protected, EMC Compliant, 3.3 V,20 Mbps, EIA RS-485 Transceiver

FUNCTIONAL BLOCK DIAGRAM

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FEATURES

Operates with +3.3 V Supply

ESD Protection: 8 kV Meets IEC1000-4-2EFT Protection: 2 kV Meets IEC1000-4-4

EIA RS-422 and RS-485 Compliant Over Full CM Range 19 k Input Impedance

Up to 50 Transceivers on Bus 20 Mbps Data Rate

Short Circuit Protection

Specified Over Full Temperature Range Thermal Shutdown

Interoperable with 5 V Logic 1 mA Supply Current 2 nA Shutdown Current 8 ns Skew

APPLICATIONS

Telecommunications DTE-DCE Interface Packet Switching Local Area Networks Data Concentration Data Multiplexers

Integrated Services Digital Network (ISDN)AppleTalk

Industrial Controls

GENERAL DESCRIPTION

The ADM3485E is a low power differential line transceiver designed to operate using a single +3.3 V power supply. Low power consumption makes it ideal for power sensitive applica-tions. It is suitable for communication on multipoint bus trans-mission lines. Internal protection against electrostatic discharge (ESD) and electrical fast transient (EFT) allows operation in electrically harsh environments.

It is intended for balanced data transmission and complies with both EIA Standards RS-485 and RS-422. It contains a differen-tial line driver and a differential line receiver, and is suitable for half duplex data transfer.

The input impedance is 19 k allowing up to 50 transceivers to be connected on the bus.

Excessive power dissipation caused by bus contention or by output shorting is prevented by a thermal shutdown circuit.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 ADM3485E is fabricated on BiCMOS, an advanced mixed technology process combining low power CMOS with fast switching bipolar technology.

The ADM3485E is fully specified over the industrial tem-perature range and is available in 8-lead DIP and SOIC packages.