DS8921/DS8921A/DS8921AT

Differential Line Driver and Receiver Pair

General Description

The DS8921, DS8921A are Differential Line Driver and Re-

ceiver pairs designed specifically for applications meeting

the ST506, ST412 and ESDI Disk Drive Standards. In addi-

tion, these devices meet the requirements of the EIA Stan-

dard RS-422.

The DS8921, DS8921A receivers offer an input sensitivity of

esis is incorporated (typically 70 mV) to improve noise mar-

gin for slowly changing input waveforms.

The DS8921, DS8921A drivers are designed to provide uni-

polar 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.

The DS8921, DS8921A are designed to be compatible with

TTL and CMOS.

Features

n 12 ns typical propagation delay

n Output skew - 0.5 ns typical

n Meet the requirements of EIA Standard RS-422

n Complementary Driver Outputs

n High differential or common-mode input voltage ranges

n Receiver input hysteresis-70 mV typical

n DS8921AT industrial temperature

operation: (−40˚C to +85˚C)

Connection Diagram

Truth Table

Receiver

Driver

Input

V

OUT

Input

V

OUT

V

OUT

V

1

1

1

0

V

0

0

0

1

Open

1

DS008512-1

Order Number DS8921M, DS8921N, DS8921AM, DS8921AN,

DS8921ATM, or DS8921ATN

See NS Package Number M08A or N08E

May 1998

© 1998 National Semiconductor Corporation

DS008512

www.national.com