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 RDS(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.