Patent ID: 7852032

Claim:
An AD conversion control circuit comprising: a selector for selecting an analog signal group to be used for PWM control out of a plurality of analog signals output by a load PWM controlled based on a PWM control signal of a plurality of phases output by a PWM control circuit according to duty ratios set in a plurality of duty ratio setting registers of the PWM circuit; an AD converter for AD converting the analog signal group and generating a digital signal group that becomes control data for duty ratio setting in the duty ratio setting register, and providing the generated digital signal group to a control unit for controlling the PWM circuit; a duty ratio comparison circuit for comparing the duty ratios set by the plurality of duty ratio setting registers; and an AD conversion channel selection circuit for controlling an analog signal group selecting operation by the selector based on a comparison result of the duty ratio comparison circuit, wherein the AD conversion channel selection circuit controls the selector by selecting two channels to implement AD conversion based on the comparison result of the duty ratio comparison circuit, and selects the largest duty ratio phase and the second largest duty ratio phase for the two channels to be AD converted.