Methods and apparatus to control a digital power supply are disclosed. An example method includes calculating a duty cycle of a pulse width modulated signal to control an output of a digital power supply, initializing an output of a counter that forms a pulse width modulator to increment by a first increment up to a counter maximum value for a first period and to decrement by the first increment for a second period, dividing the duty cycle by a constant to determine a multiple of the duty cycle to apply to each power stage of the power supply, calculating a first threshold percent by subtracting the multiple of the duty cycle from one hundred percent, setting a first threshold to be the first threshold percent multiplied by the counter maximum value, and controlling the power factor controller based on the first threshold.