LM105/LM305/LM305A

Voltage Regulators

General Description

The LM105 series are positive voltage regulators similar to

the LM100, except that an extra gain stage has been added

for improved regulation. A redesign of the biasing circuitry re-

moves any minimum load current requirement and at the

same time reduces standby current drain, permitting higher

voltage operation. They are direct, plug-in replacements for

the LM100 in both linear and switching regulator circuits with

output voltages greater than 4.5V. Important characteristics

of the circuits are:

•

Output voltage adjustable from 4.5V to 40V

•

Output currents in excess of 10A possible by adding ex-

ternal transistors

•

Load regulation better than 0.1%, full load with current

limiting

•

DC line regulation guaranteed at 0.03%/V

•

Ripple rejection on 0.01%V

•

45 mA output current without external pass transistor

(LM305A)

Like the LM100, they also feature fast response to both load

and line transients, freedom from oscillations with varying re-

sistive and reactive loads and the ability to start reliably on

any load within rating. The circuits are built on a single silicon

chip and are supplied in a TO-99 metal can.

The LM105 is specified for operation for −55˚C

≤ T

+125˚C, and the LM305/LM305A is specified for 0˚C

≤ T

+70˚C.

Schematic and Connection Diagrams

DS007755-1

Metal Can Package

DS007755-3

Top View

Order Number LM105H, LM105H/883,

SMD #5962-8958801, LM305H or LM305AH

See NS Package Number H08C

June 1999

© 1999 National Semiconductor Corporation

DS007755

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