Patent ID: 8352760

Claim:
A power supply circuit, comprising: a power controller connected to a Southbridge chip of a motherboard, wherein the Southbridge chip outputs status signals of the motherboard, the power controller provides a 5-volt system (+5V_SYS) voltage or a 5-volt standby (+5V_SB) voltage to a universal serial bus (USB) connector according to the status signals; wherein a first power pin of the power controller is capable of receiving a +5V_SYS voltage from the motherboard, a second power pin of the power controller is capable of receiving a +5V_SB voltage of the motherboard, an output pin of the power controller is connected to the USB connector for supplying the +5V_SYS voltage or the +5V_SB voltage to the USB connector, a status pin of the power controller is connected to the Southbridge chip, an enable pin of the power controller is connected to a general purpose input/output pin of the motherboard; and a switch connected to the USB connector, a USB controller, and the Southbridge chip, wherein the switch connects or disconnects the USB connector and the USB controller according to the status signals.