1

LT1129/LT1129-3.3/LT1129-5

Micropower Low Dropout

Regulators with Shutdown

APPLICATI

TYPICAL

OUTPUT CURRENT (A)

0

0.4

0.5

0.6

0.3

0.5

0.3

0.2

0.1

0.2

0.4

0.6

0.7

0.1

0

LT1129 • TA02

Dropout Voltage

5V Supply with Shutdown

DESCRIPTIO

S

FEATURE

The LT1129/LT1129-3.3/LT1129-5 are micropower low

dropout regulators with shutdown. The devices are ca-

pable of supplying 700mA of output current with a drop-

out voltage of 0.4V at maximum output. Designed for use

in battery-powered systems the low quiescent current,

50

µA operating and 16µA in shutdown, make them

an ideal choice. The quiescent current does not rise

in dropout as it does with many other low dropout

PNP regulators.

Other features of the LT1129 /LT1129-3.3/LT1129-5 in-

clude the ability to operate with small output capacitors.

They are stable with only 3.3

µF on the output while most

older devices require between 10

µF and 100µF for stabil-

ity. Also the input may be connected to ground or a reverse

voltage without reverse current flow from output to input.

This makes the LT1129/LT1129-3.3/LT1129-5 ideal for

backup power situations where the output is held high and

the input is at ground or reversed. Under these conditions,

only 16

µA will flow from the output pin to ground. The

devices are available in 5-lead TO-220, 5-lead DD, and

3-lead SOT-223 packages.

s

0.4V Dropout Voltage

s

700mA Output Current

s

50

µA Quiescent Current

s

No Protection Diodes Needed

s

Adjustable Output from 3.8V to 30V

s

3.3V and 5V Fixed Output Voltages

s

Controlled Quiescent Current in Dropout

s

Shutdown

s

16

µA Quiescent Current in Shutdown

s

Stable with 3.3

µF Output Capacitor

s

Reverse Battery Protection

s

No Reverse Output Current

s

Thermal Limiting

s

Surface Mount

S

APPLICATI

s

Low Current Regulator

s

Regulator for Battery-Powered Systems

s

Post Regulator for Switching Supplies

s

5V to 3.3V Logic Regulator

IN

OUT

LT1129-5

GND

5V OUT

500mA

3.3

µF

SOLID TANTALUM

+

SENSE

LT1129 • TA01

< 0.25

> 2.8

NC

OUTPUT

OFF

ON

ON

SHDN

1

2

3

4

5