Patent ID: 8773103

Claim:
A power supply device, comprising: a step-down unit configured to step down an input voltage; a switching unit configured to perform switching on a stepped-down voltage obtained through stepping down by the step-down unit so as to externally output an output voltage; an output variation detection unit configured to detect a corresponding variation of the output voltage from the switching unit; a delay unit configured to delay the input voltage by a determined time period determined based on a step-down delay time the step-down unit takes for the stepping down of the input voltage; a delay variation detection unit configured to detect a corresponding variation of a delayed voltage output from the delay unit; an addition unit configured to add the corresponding variation of the output voltage without delay and the corresponding variation of the delayed voltage respectively detected by the output variation detection unit and the delay variation detection unit; and a control unit configured to perform a feedback control on an operation of the switching unit based on an addition result of the addition unit.