TLH7785

January 1995

LM145LM345 Negative Three Amp Regulator

General Description

The LM145 is a three-terminal negative regulator with a

bility This device needs only one external componenta

compensation capacitor at the output making it easy to ap-

ply Worst case guarantees on output voltage deviation due

to any combination of line load or temperature variation

assure satisfactory system operation

Exceptional effort has been made to make the LM145 im-

mune to overload conditions The regulator has current lim-

iting which is independent of temperature combined with

thermal overload protection Internal current limiting pro-

tects against momentary faults while thermal shutdown pre-

vents junction temperatures from exceeding safe limits dur-

ing prolonged overloads

Although primarily intended for fixed output voltage applica-

tions the LM145 may be programmed for higher output volt-

ages with a simple resistive divider The low quiescent drain

current of the device allows this technique to be used with

good regulation

The LM145 comes in a hermetic TO-3 package rated at

25W A reduced temperature range part LM345 is also avail-

able

Features

Y

Y

Current limit constant with temperature

Y

Internal thermal shutdown protection

Y

Operates with input-output voltage differential of 28V at

full rated load over full temperature range

Y

Regulation guaranteed with 25W power dissipation

Y

3A output current guaranteed

Y

Only one external component needed

Y

Schematic Diagram

TLH7785 – 1

C1995 National Semiconductor Corporation

RRD-B30M115Printed in U S A