Patent ID: 8686656

Claim:
A power supply device, comprising: a converter that supplies electric power by performing an ON and OFF operation of a switching element; a voltage detector that detects a voltage value of an output voltage of the converter; a conversion circuit that converts the voltage value into a digital value; an arithmetic circuit that receives an operation clock signal, that respectively calculates first and second control command values at different timings based on the digital value and that calculates a difference value between the first and second control command values; a signal output circuit that outputs a first signal or a second signal toward a discharge and charge terminal, that includes a charge terminal and a discharge terminal as a pair, based on the difference value calculated by the arithmetic circuit and that adjusts output periods of the first signal and the second signal; a discharge and charge circuit that includes a capacitor; a ramp signal generation circuit that outputs a ramp signal synchronized to a clock signal generated based on the operation clock signal; and a driving signal generation circuit that generates a driving signal based on a comparison result of the ramp signal with a voltage between both terminals of the capacitor, wherein the switching element performs the ON and OFF operation according to the driving signal.