Patent ID: 7372684

Claim:
A power supply device for use as a DC/DC converter including a voltage converting unit for converting a primary input DC voltage into a secondary output DC voltage, comprising: a pulse width control unit for controlling voltage converting operation of the voltage converting unit by changing a pulse width; a momentary interruption detecting unit for detecting a change in the secondary output DC voltage when the secondary output DC voltage suffers a momentary interruption over a short period of time; a full short-circuit detecting unit for detecting a change in the secondary output DC voltage when the secondary output DC voltage suffers a short circuit over a very short period of time by comparing the secondary output DC voltage with a reference voltage being close to ground; and a short-circuit control unit for stopping the pulse width control unit from controlling the voltage converting operation of the voltage converting unit a predetermined period of time after the momentary interruption detecting unit has detected that the secondary DC output voltage suffers a momentary interruption, and for stopping the pulse width control unit from controlling the voltage converting operation of the voltage converting unit immediately when the full short-circuit detecting unit detects that the secondary DC output voltage suffers a short circuit.