LT4351

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sn4351 4351fs

MOSFET Diode-OR Controller

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Low Loss Replacement for ORing Diode in Multiple

Sourced Power Supplies

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External N-Channel MOSFETs for High Current

Capability

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Internal Boost Regulator Supply for MOSFET

Gate Drive

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Wide Input Range: 1.2V to 18V

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Fast Switching MOSFET Gate Control

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Input Under and Overvoltage Detection

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STATUS and FAULT Outputs for Monitoring

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Internal MOSFET Gate Clamp

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Available in a 10-pin MSOP

, LTC and LT are registered trademarks of Linear Technology Corporation.

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Paralleled Power Supplies

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Uninterrupted Supplies

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High Availability Systems

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N + 1 Redundant Power Supplies

The LT4351 creates a near-ideal diode using external

single or back-to-back N-channel MOSFETs. This ideal

diode function permits low loss ORing of multiple power

sources. Power sources can easily be ORed together to

increase total system power and reliability with minimal

effect on supply voltage or efficiency. Disparate power

supplies can be efficiently ORed together.

The IC monitors the input supply with respect to the load

and turns on the MOSFET(s) when the input supply is

LT4351 will regulate the voltage across the MOSFET(s) to

15mV. A STATUS pin indicates the MOSFET on state.

An internal boost regulator generates the MOSFET gate

drive voltage. Low operating voltage allows for OR’ing of

supplies as low as 1.2V.

The LT4351 will disable power passage during undervolt-

age or overvoltage conditions. These voltages are set by

resistive dividers on the UV and OV pins. The undervoltage

threshold has user programmable hysteresis. Overvolt-

age detection is filtered to reduce false triggering.

The LT4351 is available in a 10-pin MSOP.

Dual 5V Redundant Supply

GATE

OUT

SW

LT4351

UV

OV

STATUS

1

µF

24.9k

1%

232

Ω

1%

1.47k

1%

10

µF

10

µF

5V

POWER

SUPPLY

1

4.7

µH

MBR0530

FAULT

GND

Si4862DY

Si4862DY

GATE

OUT

5V COMMON

SW

LT4351

UV

OV

STATUS

1

µF

24.9k

1%

232

Ω

1%

1.47k

1%

4351 TA01

4.7

µH

MBR0530

FAULT

GND

POWER

SUPPLY

2

5V

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO