Patent ID: 8270133

Claim:
A power supply control apparatus comprising: an output transistor coupled between a first power supply line and an output terminal, the output terminal being configured to be coupled with a load; a protection transistor coupled between a gate of the output transistor and a second power supply line, and bringing the output transistor into a conduction state when a polarity of a power supply coupled between the first power supply line and the second power supply line is reversed; a negative voltage control unit coupled between the first power supply line and the gate of the output transistor, and bringing the output transistor into a conduction state when the counter electromotive voltage applied to the output terminal from the load exceeds a predetermined value; a compensation transistor bringing the second power supply line and the output terminal into a conduction state when a counter electromotive voltage from the load is applied to the output terminal; and a back gate control circuit that controls the second power supply line and a back gate of each of the compensation transistor and the protection transistor to be brought into a conduction state in a standby state when the polarity of the power supply is normal.