RS-422 Dual Differential Line Driver and Receiver Pairs

General Description

The DS8922/22A and DS8923A are Dual Differential Line

Driver and Receiver pairs. These devices are designed spe-

cifically for applications meeting the ST506, ST412 and

ESDI Disk Drive Standards. In addition, the devices meet the

requirements of the EIA Standard RS-422.

These devices offer an input sensitivity of 200 mV over a

rated (typically 70 mV) to improve noise margin for slowly

changing input waveforms. An input fail-safe circuit is pro-

vided such that if the receiver inputs are open the output as-

sumes the logical one state.

The DS8922A and DS8923A drivers are designed to provide

unipolar differential drive to twisted pair or parallel wire trans-

mission lines. Complementary outputs are logically ANDed

and provide an output skew of 0.5 ns (typ.) with propagation

delays of 12 ns.

Both devices feature TRI-STATE outputs. The DS8922/22A

have independent control functions common to a driver and

receiver pair. The DS8923A has separate driver and receiver

control functions.

Power up/down circuitry is featured which will TRI-STATE

the outputs and prevent erroneous glitches on the transmis-

sion lines during system power up or power down operation.

The DS8922/22A and DS8923A are designed to be compat-

ible with TTL and CMOS.

Features

n 12 ns typical propagation delay

n Meets the requirements of EIA Standard RS-422

n Complementary Driver Outputs

n High differential or common-mode input voltage ranges

n Receiver input fail-safe circuitry

n Receiver input hysteresis — 70 mV typical

n Glitch free power up/down

n TRI-STATE outputs

Connection Diagrams

DS8922A Dual-In-Line

DS008511-1

Order Number DS8922M, DS8922N,

DS8922AM or DS8922AN

See NS Package Number M16A or N16E

June 1998

© 1998 National Semiconductor Corporation

DS008511

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