Patent ID: 8880911

Claim:
A power supply apparatus comprising: an output unit that converts a first DC voltage input into a second DC voltage lower than the first DC voltage, and outputs the second DC voltage; a capacitor that smoothes the second DC voltage as a smoothed second DC voltage; a detection unit that detects that a power is cut off from a commercial power source; and a control unit that is capable of setting a mode of the power supply apparatus to a non-voltage-applying mode in which the smoothed second DC voltage is not applied to a load to which the smoothed second DC voltage can be applied; and a protection unit that stops the first DC voltage from being input to the output unit in a case where the second DC voltage is higher than the first DC voltage, wherein the control unit, in a case where the detection unit detects that the power is cut off in the non-voltage-applying mode, applies the smoothed second DC voltage into the load to which the smoothed second DC voltage is not applied in the non-voltage-applying mode so as to discharge charges in the capacitor, so that a condition is maintained in which the second DC voltage is lower than the first DC voltage.