The LTC4412HV controls an external P-channel MOSFET to create a near ideal diode function for power switchover or load sharing. This permits highly efficient OR'ing of multiple power sources for extended battery life and low selfheating. When conducting, the voltage drop across the MOSFET is typically 20mV. For applications with a wall adapter or other auxiliary power source, the load is automatically disconnected from the battery when the auxiliary source is connected. Two or more LTC4412HVs may be interconnected to allow load sharing between multiple batteries or charging of multiple batteries from a single charger. The LTC4412HV is an extended supply and temperature range version of the LTC4412.