A circuit for charging a battery by selecting among two available power sources while providing overcharging and temperature protection to the battery and managing a charging current is described. A power pass and sense circuit is arranged to provide charge voltage from either power source based on control voltages from a current/voltage control circuit, which receives control signals from a logic control and timer circuit, a sensed voltage from a current setting circuit and reference and temperature voltages from a voltage reference and thermo-sense circuit. Differential amplifiers controlling power pass transistors are turned on and off depending on a power source availability and selection. A power supply circuit provides global supply voltages to all subcircuits preventing reverse current to power sources and stable supply independent of a power source availability. A pair of transistors arranged to operate as body-switcher protect power pass and sense transistors against reverse bias current.