TLH5271

February 1995

LM1921 1 Amp Industrial Switch

General Description

The LM1921 Relay Driver incorporates an integrated power

PNP transistor as the main driving element The advantages

of this over previous integrated circuits employing NPN

power elements are several Greater output voltages are

available off the same supply for driving grounded loads

typically 45 volts for a 500 mA load from a 50 volt supply

The output can swing below ground potential up to 57 volts

negative with respect to the positive power supply This can

be used to facilitate rapid decay times in inductive loads

Also the IC is immune to negative supply voltages or tran-

sients The inherent Safe Operating Area of the lateral PNP

allows use of the IC as a bulb driver or for capacitive loads

Familiar integrated circuit features such as short circuit pro-

tection and thermal shutdown are also provided The input

voltage threshold levels are designed to be TTL CMOS

and LSTTL compatible over the entire operating tempera-

ture range If several drivers are used in a system their

inputs andor outputs may be combined and wired together

if their supply voltages are also common

Features

Y

1 Amp output drive

Y

Load connected to ground

Y

Low input-output voltage differential

Y

a

60 volt positive transient protection

Y

b

50 volt negative transient protection

Y

Automotive reverse battery protection

Y

Short circuit proof

Y

Internal thermal overload protection

Y

Unclamped output for fast decay times

Y

TTL LSTTL CMOS compatible input

Y

Plastic TO-220 package

Y

100% electrical burn-in

Applications

Y

Relays

Y

Solenoids

Y

Valves

Y

Motors

Y

Lamps

Y

Heaters

Typical Application Circuit

Required for stability

TLH5271 – 1

FIGURE 1 Test and Application Circuit

Connection Diagram

TLH5271 – 2

Front View

Order Number LM1921T

See NS Package Number T05A

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A