TLH7767

November 1994

LM120LM320

Series 3-Terminal Negative Regulators

General Description

The LM120 series are three-terminal negative regulators

up to 15A load current capability Where other voltages are

required the LM137 and LM137HV series provide an output

The LM120 need only one external componenta compen-

sation capacitor at the output making them easy to apply

Worst case guarantees on output voltage deviation due to

any combination of line load or temperature variation as-

sure satisfactory system operation

Exceptional effort has been made to make the LM120 Se-

ries immune to overload conditions The regulators have

current limiting which is independent of temperature com-

bined with thermal overload protection Internal current limit-

ing protects against momentary faults while thermal shut-

down prevents junction temperatures from exceeding safe

limits during prolonged overloads

Although primarily intended for fixed output voltage applica-

tions the LM120 Series may be programmed for higher out-

put voltages with a simple resistive divider The low quies-

cent drain current of the devices allows this technique to be

used with good regulation

Features

Y

Y

Preset current limit

Y

Internal thermal shutdown

Y

Operates with input-output voltage differential down to

1V

Y

Excellent ripple rejection

Y

Low temperature drift

Y

Easily adjustable to higher output voltage

LM120 Series Packages and Power Capability

Rated

Design

Device

Package

Power

Load

Dissipation

Current

LM120LM320

TO-3 (K)

20W

15A

TO-39 (H)

2W

05A

LM320

TO-220 (T)

15W

15A

LM320M

TO-202 (P)

75W

05A

Typical Applications

Dual Trimmed Supply

TLH7767 – 3

Fixed Regulator

TLH7767 – 2

Required if regulator is separated from filter capacitor by more than 3

For

value given capacitor must be solid tantalum 25 mF aluminum electrolytic

may be substituted

Required for stability For value given capacitor must be solid tantalum 25

m

F aluminum electrolytic may substituted Values given may be increased

without limit

For output capacitance in excess of 100 mF a high current diode from

input to output (1N4001 etc) will protect the regulator from momentary

input shorts

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A