LM1921 1 Amp Industrial Switch
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 4 5 volts for a 500 mA load from a 5 0 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 and or outputs may be combined and wired together
if their supply voltages are also common
Features
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
1 Amp output drive
Load connected to ground
Low input-output voltage differential
a
60 volt positive transient protection
b
50 volt negative transient protection
Automotive reverse battery protection
Short circuit proof
Internal thermal overload protection
Unclamped output for fast decay times
TTL LSTTL CMOS compatible input
Plastic TO-220 package
100% electrical burn-in
Applications
Y
Y
Y
Y
Y
Y
Relays
Solenoids
Valves
Motors
Lamps
Heaters
Typical Application Circuit
Required for stability
TL H 5271 鈥?1
FIGURE 1 Test and Application Circuit
Connection Diagram
TL H 5271 鈥?2
Front View
Order Number LM1921T
See NS Package Number T05A
C
1995 National Semiconductor Corporation
TL H 5271
RRD-B30M115 Printed in U S A
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