LMS75LBC176

Differential Bus Transceivers

General Description

The LMS75LBC176 is a differential bus/line transceiver de-

signed for bidirectional data communication on multipoint

bus transmission lines. It is designed for balanced transmis-

sion lines. It meets TIA/EIA RS485 and ISO 8482:1987(E).

line driver and differential input receiver, both of which oper-

ate from a single 5.0V power supply. The driver and receiver

have an active high and active low enable, respectively, that

can be externally connected to function as a direction con-

trol. The driver and receiver differential inputs are internally

connected to form differential input/output (I/O) bus ports

that are designed to offer minimum loading to bus whenever

the driver is disabled or when V

wide positive and negative common mode voltage ranges,

making the device suitable for multipoint applications in

noisy environments. The LMS75LBC176 is available in a

8-Pin SOIC package. It is a drop-in socket replacement to

TI’s SN75LBC176.

Features

n

Bidirectional transceiver

n

Meet ANSI standard RS-485

n

Low skew, 6ns

n

Low supply current, 8mA (max)

n

Wide input and output voltage range

n

n

Thermal shutdown protection

n

Open circuit fail-safe for receiver

n

n

Receiver input hysteresis 10mV (min.)

n

Single supply voltage operation, 5V

n

Glitch free power-up and power-down operation

n

Pin and functional compatible with TI’s SN75LBC176

n

8-Pin SOIC

Applications

n

Network hubs, bridges, and routers

n

Point of sales equipment (ATM, barcode readers,…)

n

Industrial programmable logic controllers

n

High speed parallel and serial applications

n

Multipoint applications with noisy environment

Typical Application

20047901

A typical multipoint application is shown in the above figure. Terminating resistors, RT, are typically required but only located at the two ends of the cable.

Pull up and pull down resistors maybe required at the end of the bus to provide failsafe biasing. The biasing resistors provide a bias to the cable when all

drivers are in TRI-STATE, See National Application Note, AN-847 for further information.

April 2003

© 2003 National Semiconductor Corporation

DS200479

www.national.com