LP4950C-5V and LP4951C

Adjustable Micropower Voltage Regulators

General Description

The LP4950C and LP4951C are micropower voltage regu-

lators with very low quiescent current (75µA typ.) and very

low dropout voltage (typ. 40mV at light loads and 380mV at

100mA). They are ideally suited for use in battery-powered

systems.

Furthermore,

the

quiescent

current

of

the

LP4950C/LP4951C increases only slightly in dropout, pro-

longing battery life.

The LP4950C in the popular 3-pin TO-92 package is pin

compatible with older 5V regulators. The 8-lead LP4951C is

available in a plastic surface mount package and offers

additional system functions.

One such feature is an error flag output which warns of a low

output voltage, often due to falling batteries on the input. It

may be used for a power-on reset. A second feature is the

logic-compatible shutdown input which enables the regulator

to be switched on and off. Also, the part may be pin-strapped

for a 5V output or programmed from 1.24V to 29V with an

external pair of resistors.

Careful design of the LP4950C/LP4951C has minimized all

contributions to the error budget. This includes a tight initial

tolerance (.5% typ.), extremely good load and line regulation

(.05% typ.) and a very low output voltage temperature coef-

ficient, making the part useful as a low-power voltage refer-

ence.

Features

n

High accuracy 5V guaranteed 100mA output

n

Extremely low quiescent current

n

Low dropout voltage

n

Extremely tight load and line regulation

n

Very low temperature coefficient

n

Use as Regulator or Reference

n

Needs only 1µF for stability

n

Current and Thermal Limiting

LP4951C versions only

n

Error flag warns of output dropout

n

Logic-controlled electronic shutdown

n

Output programmable from 1.24 to 29V

Block Diagram and Typical

Applications

LP4950C

LP4951C

20052825

20052801

September 2002

© 2002 National Semiconductor Corporation

DS200528

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