AAT3238IGU-1.85-T1 데이터 시트보기 (PDF) - Advanced Analogic Technologies

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AAT3238IGU-1.85-T1

300mA MicroPower™ High Performance LDO Linear Regulator

Advanced Analogic Technologies 

PowerLinearTM

PRODUCT DATASHEET

AAT3238

300mA MicroPowerTM High Performance LDO Linear Regulator

Functional Block Diagram

IN

OUT

Active

Feedback

Control

Over-Current

Protection

Over-

Temperature

Protection

+

Error

Amplifier

-

Fast

EN

Start

Control

Voltage

Reference

BYP

Functional Description

The AAT3238 is intended for LDO regulator applications

where output current load requirements range from no

load to 300mA.

The advanced circuit design of the AAT3238 has been

specifically optimized for very fast start-up and shut-

down timing. This proprietary CMOS LDO has also been

tailored for superior transient response characteristics.

These traits are particularly important for applications

that require fast power supply timing, such as GSM cel-

lular telephone handsets.

The high-speed turn-on capability of the AAT3238 is

enabled through the implementation of a fast start con-

trol circuit, which accelerates the power-up behavior of

fundamental control and feedback circuits within the

LDO regulator.

Fast turn-off response time is achieved by an active output

pull-down circuit, which is enabled when the LDO regulator

is placed in the shutdown mode. This active fast shutdown

circuit has no adverse effect on normal device operation.

The AAT3238 has very fast transient response character-

istics, which is an important feature for applications

where fast line and load transient response is required.

GND

This rapid transient response behavior is accomplished

through the implementation of an active error amplifier

feedback control. This proprietary circuit design is unique

to this MicroPower LDO regulator.

The LDO regulator output has been specifically optimized

to function with low-cost, low-ESR ceramic capacitors.

However, the design will allow for operation over a wide

range of capacitor types.

A bypass pin has been provided to allow the addition of

an optional voltage reference bypass capacitor to reduce

output self noise and increase power supply ripple rejec-

tion. Device self noise and PSRR will be improved by the

addition of a small ceramic capacitor in this pin. However,

increased values of CBYPASS may slow down the LDO regu-

lator turn-on time.

This LDO regulator has complete short-circuit and ther-

mal protection. The integral combination of these two

internal protection circuits gives the AAT3238 a compre-

hensive safety system to guard against extreme adverse

operating conditions. Device power dissipation is limited

to the package type and thermal dissipation properties.

Refer to the Thermal Considerations section of this

datasheet for details on device operation at maximum

output current loads.

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3238.2008.05.1.7

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