LM123/LM323A/LM323

3-Amp, 5-Volt Positive Regulator

General Description

The LM123 is a three-terminal positive regulator with a pre-

set 5V output and a load driving capability of 3 amps. New

circuit design and processing techniques are used to provide

the high output current without sacrificing the regulation

characteristics of lower current devices.

The LM323A offers improved precision over the standard

LM323. Parameters with tightened specifications include

output voltage tolerance, line regulation, and load regulation.

The 3 amp regulator is virtually blowout proof. Current limit-

ing, power limiting, and thermal shutdown provide the same

high level of reliability obtained with these techniques in the

LM109 1 amp regulator.

No external components are required for operation of the

LM123. If the device is more than 4 inches from the filter ca-

pacitor, however,a1µF solid tantalum capacitor should be

used on the input. A 0.1 µF or larger capacitor may be used

on the output to reduce load transient spikes created by fast

switching digital logic, or to swamp out stray load capaci-

tance.

An overall worst case specification for the combined effects

of input voltage, load currents, ambient temperature, and

power dissipation ensure that the LM123 will perform satis-

factorily as a system element.

For applications requiring other voltages, see LM150 series

adjustable regulator data sheet.

Operation is guaranteed over the junction temperature range

−55˚C to +150˚C for LM123, −40˚C to +125˚C for LM323A,

and 0˚C to +125˚C for LM323. A hermetic TO-3 package is

used for high reliability and low thermal resistance.

Features

n Guaranteed 1% initial accuracy (A version)

n 3 amp output current

n Internal current and thermal limiting

n 0.01

Ω typical output impedance

n 7.5V minimum input voltage

n 30W power dissipation

n P

Connection Diagram

Typical Applications

Metal Can Package

DS007771-2

Order Number LM123K STEEL, LM323AK STEEL or LM323K STEEL

See NS Package Number K02A

Order Number LM123K/883

See NS Package Number K02C

Basic 3 Amp Regulator

DS007771-3

*Required if LM123 is more than 4" from filter capacitor.

April 1998

© 1999 National Semiconductor Corporation

DS007771

www.national.com