A control circuit adjusts the duty cycle of a PWM control signal. An analog processing component within the control circuit receives an analog feedback input signal and compares it to an analog reference signal to generate a pre-processed signal. A sigma-delta modulator within the analog processing component generates a quantized signal based on the pre-processed signal. A digital processing component stores a value. The controller then adjusts the duty cycle of the PWM signal to correspond to the value. A clock keeps the system synchronized.