August 1999

1

MIC2954

MIC2954

Micrel

MIC2954

250mA Low-Dropout Regulator

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

Features

• High-accuracy 5V, guaranteed 250mA output

• Low quiescent current

• Low dropout voltage

• Extremely tight load and line regulation

• Very low temperature coefficient

• Current and thermal limiting

• Input can withstand –20V reverse battery and

+60V positive transients

• Error flag warns of low output voltage

• Logic-controlled electronic shutdown

• Output programmable from 1.24V to 29V

(MIC2954-07/08)

• Available in TO-220, TO-92, and surface-mount

SOT-223 and SOP-8 packages

Applications

• Battery powered equipment

• Cellular telephones

• Laptop, notebook, and palmtop computers

• PCMCIA V

• Bar code scanners

• Automotive electronics

• SMPS post-regulator/dc-to-dc modules

• Voltage reference

• High-efficiency linear power supplies

General Description

The MIC2954 is a “bulletproof” efficient voltage regulator with

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

375mV at 250mA), and low quiescent current (120

µA typi-

cal). The quiescent current of the MIC2954 increases only

slightly in dropout, thus prolonging battery life. Key MIC2954

features include protection against reversed battery, fold-

back current limiting, and automotive load dump protection

(60V positive transient).

The MIC2954-07/08BM is an adjustable version that includes

an error flag output that warns of a low output voltage, which

is often due to failing batteries on the input. This may also be

used as a power-on reset. A logic-compatible shutdown input

is provided which enables the regulator to be switched on and

off. This part may be pin-strapped for 5V output, or pro-

grammed from 1.24V to 29V with the use of two external

resistors.

The MIC2954 is available in two voltage tolerances,

±0.5%

maximum and

±1% maximum. Both are guaranteed for

junction temperatures from –40

°C to +125°C.

The MIC2954 has a very low output voltage temperature

coefficient and extremely good load and line regulation

(0.04% typical).

Typical Applications

MIC2954

IN

OUT

GND

2.2µF

5V Fixed Regulator

SHUTDOWN

ENABLE

MIC2954-07/-08

IN

OUT

GND

3.3µF

+7V

5V or 3.3V

SHDN

FB

300k

1%

100pF

180k

1%

ERR

Q1 ON = 3.3V

Q1 OFF = 5.0V

1

3

8

5

7

4

220k

1%

Q1

2N2222

5V

3.3V

470k

5V or 3V Selectable Regulator with Shutdown

SHUTDOWN

ENABLE

MIC2954

IN

OUT

GND

10µF

1.2V to 30V

SHDN

FB

R1

100pF

R2

ERR

100k

2, 6 = OPEN

1

3

8

5

7

4

VV

1

R1

R2

OUT

REF

=+









Adjustable Regulator

SHUTDOWN

ENABLE

MIC2954-07/-08

IN

OUT

GND

SHDN

FB

ERR

* MINIMUM INPUT-TO-OUTPUT

VOLTAGE RANGES FROM

40mV TO 400mV DEPENDING

UPON LOAD CURRENT

1

3

8

5

7

4

Wide Input-Voltage-Range Current Limiter