LT4356-1/LT4356-2

1

4356fa

APPLICATIONS

FEATURES

DESCRIPTION

Surge Stopper

transients. It regulates the output during an overvoltage

event, such as load dump in automobiles, by controlling

the gate of an external N-channel MOSFET. The output is

limited to a safe value thereby allowing the loads to con-

tinue functioning. The LT4356 also monitors the voltage

overcurrent faults. An internal amplifier limits the current

sense voltage to 50mV. In either fault condition, a timer

is started inversely proportional to MOSFET stress. If the

timer expires, the FLT pin pulls low to warn of an impend-

ing power down. If the condition persists, the MOSFET is

turned off. After a cool down period, the GATE pin pulls

up turning on the MOSFET again.

The auxiliary amplifier may be used as a voltage detection

comparator or as a linear regulator controller driving an

external PNP pass transistor.

Back-to-back FETs can be used in lieu of a Schottky diode

for reverse input protection, reducing voltage drop and

power loss. A shutdown pin reduces the quiescent current

to less than 7μA for the LT4356-1 during shutdown. The

LT4356-2 differs from the LT4356-1 during shutdown by

reducing the quiescent current to 60μA and keeping alive

the auxiliary amplifier for uses such as an undervoltage

lockout or always-on regulator.

Linear Regulator Controller

× 3mm) 12-Pin DFN,

10-Pin MSOP or 16-Pin SO Packages

4A, 12V Overvoltage Output Regulator

Overvoltage Protector Regulates Output at

27V During Transient

0.1μF

10Ω

10mΩ

IRLR2908

12V

4356 TA01

LT4356DE

GND

TMR

OUT

GATE

SNS

SHDN

FAULT

EN

FLT

UNDERVOLTAGE

FB

DC-DC

CONVERTER

GND

SHDN

4.99k

383k

100k

102k

100ms/DIV

4356 TA01b

20V/DIV

20V/DIV

80V INPUT SURGE

27V ADJUSTABLE CLAMP

12V

12V

TYPICAL APPLICATION

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