Patent ID: 7023180

Claim:
A charging apparatus comprising: first and second input terminals to which power voltage sources are connected; first and second semiconductor devices for power control in which said first and second input terminals are connected to input electrodes, respectively; a secondary battery to which output electrodes of said first and second semiconductor devices for power control are connected in common and which is connected between said common connection electric potential point and a reference electric potential point; a control circuit for controlling a terminal voltage and a charge current of said secondary battery to desired values; switching signal generating means for detecting voltages which are generated at the input electrodes of said first and second semiconductor devices for power control and generating a switching signal for turning on a circuit between the input and output electrodes of said semiconductor device for power control at which the voltage has been detected; and a stabilizing circuit that stabilizes the power voltage sources detects and includes at least one of an overcurrent protection circuit, a charge stop circuit, a constant current detecting circuit, and a constant voltage detection circuit, wherein if the voltages are detected from the input electrodes of both of said first and second semiconductor devices for power control, the input power sources are controlled by turning on the circuit between the input and output electrodes of one of said first and second semiconductor devices such that in accordance with a priority protocol the semiconductor device located on the side in which the voltage is equal to or larger than a predetermined minimum voltage value is selected.