Patent ID: 8296589

Claim:
A power supply circuit, comprising: a PWM controller capable of providing pulse signals to a CPU; and an I/O controller electrically coupled to the PWM controller and the CPU respectively, wherein the I/O controller is capable of receiving voltage selection signals from the CPU and outputting a control signal to the PWM controller; and the PWM controller is capable of adjusting pulse signals provided to the CPU according to the control signal; wherein the I/O controller comprises a detecting output terminal capable of outputting detection signals that determine whether the CPU is installed in the circuit, the CPU comprises a status determination terminal electrically coupled to the detecting output terminal for receiving the detection signals; the CPU is capable of outputting a feedback signal to the I/O controller at the status determination terminal upon receiving the detection signals; and the I/O controller is capable of determining whether the CPU is installed in the circuit according to the feedback signal.