LTC4367 datasheet(7/24 Pages) AD

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LTC4381

Rev. 0

For more information www.analog.com

TYPICAL PERFORMANCE CHARACTERISTICS

RON vs Temperature

RON vs VCC

MOSFET SOA Curve

VCC = 12V, unless otherwise noted.

PIN FUNCTIONS

DRN: MOSFET Drain-Source Sense. The DRN pin voltage

tracks the OUT pin. The resulting DRN pin current through

external resistor RDRN is proportional to the MOSFET VDS.

The DRN pin current and ∆VSNS (SNS – OUT) are mul-

tiplied internally to produce a TMR pin current approxi-

mately proportional to the MOSFET’s power dissipation.

This reduces the SOA requirement of the MOSFET by tim-

ing out faster during more severe faults. Choose RDRN to

limit the current to 1mA at the peak input voltage. Connect

to OUT if unused.

FLT: Fault Output. This open-drain logic output pin pulls

low after the voltage at the TMR pin has reached the fault

threshold of 1.215V. It indicates that the MOSFET is off

because either the supply voltage has stayed at an ele-

vated level for an extended period of time (voltage fault)

or the device is in an overcurrent condition (current fault).

The fault output is capable of sinking up to 3mA. Leave

open or tie to GND if unused.

GATE: Gate Drive for Internal N-Channel MOSFET. The

GATE pin is pulled up by an internal 20µA charge pump

that is regulated to 11.5V above the OUT pin. An amplifier

controls the GATE pin to limit the current through the

MOSFET. A minimum of 47nF of capacitance and 33Ω

series resistor at the pin is necessary to compensate the

current limit amplifier. To avoid damaging the MOSFET

during an output short, GATE is also clamped internally

to 17V above OUT.

GFET: Gate of Internal N-Channel MOSFET. Connect this

pin to the GATE pin through a 10Ω resistor.

GND: Device Ground.

IN: Input of MOSFET. This is the drain terminal of the inter-

nal MOSFET. Connect this pin to the supply input.

ON: Turn-On Control Input. The LTC4381 can be turned

on by pulling this pin above 1.05V or by leaving it open to

allow an internal 1MΩ resistor to turn the part on. Pulling

the pin below the threshold puts the part in shutdown

mode and reduces the supply current to 5µA. Limit the ON

leakage current to less than 1µA if no external pull-up is

used. The ON pin can be pulled up to 80V or below GND

by 60V without damage.

OUT: Output Voltage Sense. This pin senses the output

voltage at the output terminal of the current sense resistor.

An internal clamp limits the voltage in between the GATE

and OUT pins to 17V. Bypass the OUT pin with a minimum

of 22µF as close to the pin as possible.

VCC = 4V

VCC = 12V

TEMPERATURE (°C)

–50 –25

75 100 125 150

4381 G19

VCC (V)

4381 G20

TA = 25°C

SINGLE PULSE

VIN–VSRC (V)

100 200

0.1

100

4381 G21

1ms

100 s

10ms

100ms

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