LT1121IS8(RevA) Просмотр технического описания (PDF) - Linear Technology

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LT1121IS8
(Rev.:RevA)

Micropower Low Dropout Regulators with Shutdown

Linear Technology 

FEATURES

s 0.4V Dropout Voltage

s 150mA Output Current

s 30µA Quiescent Current

s No Protection Diodes Needed

s Adjustable Output from 3.8V to 20V

s 3.3V and 5V Fixed Output Voltages

s Controlled Quiescent Current in Dropout

s Shutdown

s 16µA Quiescent Current in Shutdown

s Stable with 0.33µF Output Capacitor

s Reverse Battery Protection

s No Reverse Current with Input Low

s Thermal Limiting

APPLICATI S

s Low Current Regulator

s Regulator for Battery-Powered Systems

s Post Regulator for Switching Supplies

TYPICAL APPLICATI

5V Battery-Powered Supply with Shutdown

8 IN

1

OUT

3.3V OUT

150mA

+

5V

LT1121-3.3

1µF

SOLID TANTALUM

5 SHDN

GND

3

VSHDN (PIN 5) OUTPUT

< 0.25

OFF

> 2.8

ON

NC

ON

LT1121 • TA01

LT1121/LT1121-3.3/LT1121-5

Micropower Low Dropout

Regulators with Shutdown

DESCRIPTIO

The LT1121/LT1121-3.3/LT1121-5 are micropower low

dropout regulators with shutdown. These devices are

capable of supplying 150mA of output current with a

dropout voltage of 0.4V. Designed for use in battery-

powered systems, the low quiescent current, 30µA oper-

ating and 16µA in shutdown, makes them an ideal choice.

The quiescent current is well-controlled; it does not rise in

dropout as it does with many other low dropout PNP

regulators.

Other features of the LT1121/LT1121-3.3/LT1121-5 in-

clude the ability to operate with very small output capaci-

tors. They are stable with only 0.33µF on the output while

most older devices require between 1µF and 100µF for

stability. Small ceramic capacitors can be used, enhanc-

ing manufacturability. Also the input may be connected to

ground or a reverse voltage without reverse current flow

from output to input. This makes the LT1121 series ideal

for backup power situations where the output is held high

and the input is at ground or reversed. Under these

conditions only 16µA will flow from the output pin to

ground.

Dropout Voltage

0.5

0.4

0.3

0.2

0.1

0

0 20 40 60 80 100 120 140 160

OUTPUT CURRENT (mA)

LT1121 • TA02

1

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