Patent ID: 7492614

Claim:
A switching power supply apparatus that converts a direct voltage obtained by rectifying an alternating input voltage of an alternating-current power source and by smoothing by a smoothing capacitor, into another direct voltage by switching operation of a switching element controlled by a control unit, comprising: an actuation unit configured to supply an actuation power, to start the switching operation of the switching element, to the control unit when the alternating-current power source is turned on, and to stop supply of the actuation power to the control unit after the switching operation of the switching element is started; an overheat detector thermally coupled with the actuation unit and detecting an abnormal condition due to overheating of the actuation unit; a latch unit maintaining a stopped state of the switching operation of the switching element at the event of an abnormal condition other than the abnormal condition due to overheating of the actuation unit; and an actuation controller configured to discharge an electrical charge of the smoothing capacitor while the latch unit maintains the stopped state of the switching operation to speedily reset the latch unit when the alternating-current power source is turned off, and to stop the actuation unit in response to a detection signal from the overheat detector.