Patent ID: 7917781

Claim:
A universal series bus (USB) power supply comprising: a DC power source; a USB power interface comprising a V BUS terminal being connected to the DC power source to obtain DC power; a D+ terminal; D− terminal; and a ground terminal being connected to the ground; a current feedback detection unit being connected to the ground and the ground terminal of the USB power interface, detecting whether the ground terminal of the USB power interface outputs a current and outputting a detection result signal if the ground terminal of the USB power interface outputs a current; and a voltage modulation module being connected to the current feedback detection unit and receiving the detection result signal, being connected to and outputting signals to the D+ and D− terminals of the USB power interface, controlling the voltage levels of the signals output to the D+ and D− terminals of the USB power interface and maintaining the voltage levels of the signals when the received detection result signal represents that there is a current flowing from the ground terminal of the USB power interface.