LT4351 Datasheet, PDF (1/20 Pages) Linear Technology – MOSFET Diode-OR Controller

LT4351
MOSFET Diode-OR Controller
FEATURES
s _{Low Loss Replacement for ORing Diode in Multiple}
Sourced Power Supplies
s _{External N-Channel MOSFETs for High Current}
Capability
s _{Internal Boost Regulator Supply for MOSFET}
Gate Drive
s _{Wide Input Range: 1.2V to 18V}
s _{Fast Switching MOSFET Gate Control}
s _{Input Under and Overvoltage Detection}
s _{STATUS and FAULT Outputs for Monitoring}
s _{Internal MOSFET Gate Clamp}
s _{Available in a 10-pin MSOP}
U
APPLICATIO S
s _{Paralleled Power Supplies}
s _{Uninterrupted Supplies}
s _{High Availability Systems}
s _{N + 1 Redundant Power Supplies}
, LTC and LT are registered trademarks of Linear Technology Corporation.
DESCRIPTIO
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
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 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.
TYPICAL APPLICATIO
Dual 5V Redundant Supply
POWER
SUPPLY
1
5V
10µF
1µF
24.9k
1%
232Ω
1%
1.47k
1%
MBR0530
4.7µH
Si4862DY
Si4862DY
5V COMMON
5V
C_LOAD
V_IN
GATE
OUT
V_DD
LT4351
SW
UV
STATUS
FAULT
OV
GND
R_LOAD
OUT
GATE
LT4351
STATUS
FAULT
GND
10µF
V_IN
1µF
V_DD
MBR0530
SW
4.7µH
UV
OV
POWER
SUPPLY
2
24.9k
1%
232Ω
1%
1.47k
1%
4351 TA01
sn4351 4351fs
1