Selectable phase power supply system

A power supply system to provide power for a processor, comprising:

• a bridge circuit;
• a pulse width modulation (PWM) controller;
• and
• a pulse adjusting driver circuit;
• wherein the bridge circuit detects a work state of the PWM controller to obtain a feedback signal output from the PWM controller, and provides the feedback signal to the processor, the processor outputs a control signal to the bridge circuit according to a work state thereof and the feedback signal, the bridge circuit outputs a PWM signal to the pulse adjusting driver circuit according to the control signal, and the pulse adjusting driver circuit receives a first driving signal provided by an external circuit, adjusts the PWM signal, and adjusts the first driving signal according to the adjusted PWM signal to generate at least one second driving signal having different phase to drive the processor.