LT4363

1

4363fa

100ms/DIV

4363 TA01b

20V/DIV

20V/DIV

80V INPUT SURGE

27V ADJUSTABLE CLAMP

12V

12V

transients. It regulates the output during an overvoltage

event, such as load dump in vehicles, by controlling the

gateofanexternalN-channelMOSFET.Theoutputislimited

to a safe value allowing the loads to continue functioning.

The LT4363 also monitors the voltage drop between the

SNS and OUT pins to protect against overcurrent faults.

An internal amplifier limits the voltage across the current

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

startedinverselyproportionaltoMOSFETstress.Beforethe

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

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

turned off. The LT4363-1 remains off until reset whereas

the LT4363-2 restarts after a cool down period.

Two precision comparators can monitor the input supply

for overvoltage (OV) and undervoltage (UV) conditions.

When the potential is below the UV threshold, the external

MOSFET is kept off. If the input supply voltage is above the

OV threshold, the MOSFET is not allowed to turn back on.

Back-to-back MOSFETs 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 during shutdown.

TYPICAL APPLICATION

FEATURES

DESCRIPTION

High Voltage Surge

Stopper with Current Limit

4A, 12V Overvoltage Output Regulator with 150V Surge Protection

Overvoltage Protector Regulates

Output at 27V During Transient

APPLICATIONS

n

n

Wide Operating Voltage Range: 4V to 80V

n

Adjustable Output Clamp Voltage

n

Fast Overcurrent Limit: Less Than 5µs

n

Reverse Input Protection to –60V

n

Adjustable UV/OV Comparator Thresholds

n

Low 7µA Shutdown Current

n

Shutdown Pin Withstands –60V to 100V

n

Adjustable Fault Timer

n

Controls N-Channel MOSFET

n

Less Than 1% Retry Duty Cycle During Faults,

LT4363-2

n

Available in 12-Pin (4mm

× 3mm) DFN, 12-Pin

MSOP or 16-Pin SO Packages

n

Automotive/Avionic Surge Protection

n

Hot Swap™/Live Insertion

n

High Side Switch for Battery Powered Systems

n

Intrinsic Safety Applications

L

, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

trademarks are the property of their respective owners.

0.1µF

10

10m

FDB33N25

12V

4363 TA01

LT4363-2

GND

TMR

OUT

GATE SNS

UV

SHDN

OV

FAULT

OUTPUT

CLAMP

AT 16V

ENOUT

FLT

FB

1k

SMAJ58A

22µF

0.1µF

DC/DC

CONVERTER

GND

SHDN

4.99k

127k

49.9k

57.6k