DS89C21

Differential CMOS Line Driver and Receiver Pair

General Description

The DS89C21 is a differential CMOS line driver and receiver

pair, designed to meet the requirements of TIA/EIA-422-A

(RS-422) electrical characteristics interface standard. The

DS89C21 provides one driver and one receiver in a mini-

mum footprint. The device is offered in an 8-pin SOIC pack-

age.

The CMOS design minimizes the supply current to 6 mA,

making the device ideal for use in battery powered or power

conscious applications.

The driver features a fast transition time specified at 2.2 ns,

and a maximum differential skew of 2 ns making the driver

ideal for use in high speed applications operating above

10 MHz.

The receiver can detect signals as low as 200 mV, and also

incorporates hysteresis for noise rejection. Skew is specified

at 4 ns maximum.

The DS89C21 is compatible with TTL and CMOS levels (DI

and RO).

Features

n Meets TIA/EIA-422-A (RS-422) and CCITT V.11

recommendation

n LOW POWER design — 15 mW typical

n Guaranteed AC parameters:

— Maximum driver skew 2.0 ns

— Maximum receiver skew 4.0 ns

n Extended temperature range:

−40˚C to +85˚C

n Available in SOIC packaging

n Operates over 20 Mbps

n Receiver OPEN input failsafe feature

Connection Diagram

Truth Tables

Driver

Input

Outputs

DI

DO

HH

L

LL

H

Receiver

Inputs

Output

RO

V

H

V

L

H

DS011753-1

Order Number DS89C21TM

See NS Package Number M08A

June 1998

© 1998 National Semiconductor Corporation

DS011753

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