APL5537 Просмотр технического описания (PDF) - Anpec Electronics

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APL5537

Dual Channel 300mA Low Dropout Linear Regulator

Anpec Electronics 

APL5537

Function Description

VIN Under-Voltage Lockout (UVLO)

The APL5537 has a built-in under-voltage lockout circuit

to keep the outputs shuting off until internal circuitry is

operating properly. The UVLO circuit has a hysteresis

and a de-glitch feature so that it will typically ignore un-

dershoot transients on the input.

Soft-Start (For Each Channel)

The APL5537 provides an internal soft-start circuitry to

control rise rate of the output voltage and limit the current

surge during start-up. The output voltage starts the soft-

start at approximate 60µs after the VIN is over the UVLO

threshold. The typical soft-start interval is about 60µs.

Over-Temperature Protection

An over-temperature protection circuitry limits the junc-

tion temperature of APL5537. When the junction tempera-

ture exceeds +160oC, the over-temperature protection

circuitry disables the LDO outputs, allowing the device to

cool down. The LDO outputs are enabled again after the

junction temperature cools down by 40oC, resulting in a

pulsed output during continuous thermal overload

conditions. Over-temperature protection is designed to

protect the IC in the event of over temperature conditions.

For reliable operation, the junction temperature cannot

exceed TJ=+125oC

Current-Limit Protection (For Each Channel)

The APL5537 provides a current-limit protection function.

During current limit, the device limits output current at

current limit threshold. For reliable operation, the device

should not be operated in current limit for extended period.

Short-Circuit Current-Limit Protection (For Each

Channel)

When the output voltage drops below 0.8V, which is

caused by the over load or short circuit, the device limits

the output current down to a safe level. The short circuit

current limit is used to reduce the power dissipation dur-

ing short circuit conditions. If the junction temperature is

over the over-temperature threshold, the device will enter

the thermal shutdown.

Enable/Disable (For Each Channel)

Pulling the VEN1/2 above 1.5V enables the respective LDO

output, and pulling VEN1/2 below 0.4V disables the respec-

tive LDO output. When both the LDO outputs are disabled,

the supply current is reduced to less than 1µA. EN1/2

pins are internally pulled low by resistors. If shutdown

function is not used, connect EN1/2 to VIN for normal

operation. The enable inputs are compatible with both

TTL and CMOS logic levels.

Copyright © ANPEC Electronics Corp.

9

Rev. A.7 - Oct., 2011

www.anpec.com.tw

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