Patent ID: 7969046

Claim:
A power supply control apparatus comprising: a control circuit having a switch element opening and closing a circuit by a switch signal and a switch control unit outputting the switch signal; and a load connecting a first terminal to a DC (direct-current) power supply through the switch element and connecting a second terminal directly to a ground electric potential, wherein the control circuit is not disposed between the second terminal and the ground electric potential, the switch control unit having a ground terminal connected to the ground electric potential and outputting a ground current flowing toward the ground electric potential, the control circuit having a bypass device connecting the first terminal of the load to the ground terminal, the bypass device including a load side bypass system for applying the ground current to the ground electric potential through the load when connection between the ground terminal and the ground electric potential is disconnected, the load having impedance for changing the electric potential of the ground terminal into an electric potential in which the switch control unit stably acts when the ground current flows, and the bypass device having a reverse current preventive system configured to always close a circuit so as to apply a current to the load when the bypass device is connected to the load side bypass system in series and the DC power supply is normally connected, and configured to always open the circuit so as to prevent the current from flowing into the load side bypass system when the DC power supply is connected in reverse.