Patent ID: 7923980

Claim:
A digital controlled power supply comprising: a digital controller for generating a PWM signal, the PWM signal being used to turn on and off a switching element to obtain an output voltage for a load based on an input voltage, wherein the digital controller comprises: an AD converter for receiving an analog output current from the power supply and converting the current into a digital value to thereby produce a digital output current value; arithmetic processing unit for conducting an arithmetic operation of an on-time period or an off-time period of the PWM signal for each period of a sampling frequency of the AD converter or a frequency of a carrier wave as a criterion to obtain the PWM signal; and a frequency control unit for variably controlling the frequency of the carrier wave based on the digital output current value produced from the AD converter so that a variation of a ripple current based on a DC bias characteristic of a choke coil in a filter circuit of the power supply is controlled to be within a fixed range.