Disclosed is a power supply circuit of an electric device. The power supply circuit comprises a power source configured to output a power source voltage; a power source voltage detecting circuit configured to detect the power source voltage, and to output a first voltage control signal; a leading edge delay circuit configured to receive the first voltage control signal, and to output a second voltage control signal; an electronic switch connected in series between the power source and the load, configured to turn on or turn off power supply from the power source to the load; and a slow turn-on circuit configured to receive the second voltage control signal.