A protection circuit, and related method, for an electronic device including a first power output interface and a second power output interface is disclosed. The protection circuit includes a first switch element, coupled between a first voltage source and the first power output interface. The detection circuit being operation to detect an output voltage value of the second power output interface to generate a detection result. The first switch element, according to the detection result, connects the first voltage source to the first power output interface to allow the first power output interface to output power to an external terminal, or disconnects the first voltage source from the first power output interface.