LT4351_15 Datasheet, PDF (1/20 Pages) Linear Technology – MOSFET Diode-OR Controller

FEATURES
n _{Low Loss Replacement for ORing Diode in Multiple}
Sourced Power Supplies
n _{External N-Channel MOSFETs for High Current}
Capability
n _{Internal Boost Regulator Supply for MOSFET}
Gate Drive
n _{Wide Input Range: 1.2V to 18V}
n _{Fast Switching MOSFET Gate Control}
n _{Input Under and Overvoltage Detection}
n _{STATUS and FAULT Outputs for Monitoring}
n _{Internal MOSFET Gate Clamp}
n _{Available in a 10-pin MSOP Package}
APPLICATIONS
n _{Paralleled Power Supplies}
n _{Uninterrupted Supplies}
n _{High Availability Systems}
n _{N + 1 Redundant Power Supplies}
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other
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LT4351
MOSFET Diode-OR
Controller
DESCRIPTION
The LT^®4351 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
higher. If the MOSFET’s R_DS(ON) is sufficiently small, the
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 ORing 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. Overvoltage
detection is filtered to reduce false triggering.
The LT4351 is available in a 10-pin MSOP package.
TYPICAL APPLICATION
Dual 5V Redundant Supply
POWER
SUPPLY
1
4.7µH
5V
10µF
1µF
Si4862DY
1×
5V COMMON
C_LOAD LOAD
Si4862DY
1×
V_IN
GATE
OUT
MBR0530
V_DD
MBR0530
LT4351
24.9k
SW
STATUS
1%
UV
FAULT
232Ω
1%
OV
GND
1.47k
1%
OUT
GATE
LT4351
STATUS
FAULT
GND
5V
10µF
1µF
4.7µH
V_IN
V_DD
MBR0530
MBR0530
SW
UV
OV
4351 TA01
POWER
SUPPLY
2
24.9k
1%
232Ω
1%
1.47k
1%
4351fd
1