A power supply circuit includes an energy-consuming component including an input terminal, an input over-voltage protection circuit connected to the input terminal, and a feed back circuit. The feedback circuit is connected to the input over-voltage protection circuit and the input terminal of the energy-consuming component. The feedback circuit monitors the voltage on the input terminal, compares the voltage on the input terminal with a reference voltage, and turns off the input over-voltage protection circuit to cut off voltage provided to the input terminal of the energy-consuming component when the voltage on the input terminal is larger than the reference voltage.