LP2950/2951

Micrel

3

February 1999

3-35

LP2950/2951

100mA Low-Dropout Voltage Regulator

General Description

The LP2950 and LP2951 are micropower voltage regulators

with very low dropout voltage (typically 40mV at light loads

and 380mV at 100mA), and very low quiescent current (75

µA

typical).

The quiescent current of the LP2950/LP2951

increases only slightly in dropout, thus prolonging battery life.

This feature, among others, makes the LP2950 and LP2951

ideally suited for use in battery-powered systems.

Available in a 3-Pin TO-92 package, the LP2950 is pin-

compatible with the older 5V regulators. Additional system

functions, such as programmable output voltage and logic-

controlled shutdown, are available in the 8-pin DIP and 8-pin

SOIC versions of the LP2951.

Features

•

High accuracy 5V, guaranteed 100 mA output

•

Extremely low quiescent current

•

Low-dropout voltage

•

Extremely tight load and line regulation

•

Very low temperature coefficient

•

Use as regulator or reference

•

Needs only 1

µF for stability

•

Current and thermal limiting

LP2951 Versions Only

•

Error flag warns of output dropout

•

Logic-controlled electronic shutdown

•

Output programmable from 1.24 to 29V

Block Diagram and Pin Configurations

LP2950 and LP2951 Block Diagram

(Pin Numbers Refer to LP2951)

1

2

3

4

8

7

6

5

OUTPUT

SENSE

SHUTDOWN

GROUND

ERROR

5V TAP

FEEDBACK

INPUT

GROUND

OUTPUT

INPUT

TO-92 Plastic Package Bottom View

(BZ)

DIP and SO Packages

(BN and BM)

Applications

•

Automotive Electronics

•

Voltage Reference

•

Avionics

32

1

See MIC2950 for a part with 1) higher output (150 mA), 2) transient protection (60V), and 3) reverse input protection to –20V)

5V TAP

6

SENSE

2

GROUND

4

ERROR

5

TO CMOS

OR TTL

330

k

Ω

+

1.5 µF

60

k

Ω

182

k

Ω

OUTPUT

INPUT

FEEDBACK

1

8

7

5V

150 mA

MAX.

+

–

+

–

ERROR

AMPLIFIER

ERROR

DETECTION

COMPARATOR

+

1.23 V

REF.

+

60 mV

SHUT-

DOWN

3

FROM

CMOS

OR TTL

+

UNREGULATED DC