Patent ID: 9046902
Filing Date: 2015-06-02
Classification: G05F

Abstract:
1. A power supply circuit of an electric device, comprising: a power source configured to output a power source voltage by which direct current is provided to a load; a power source voltage detecting circuit configured to detect the power source voltage, and to output a first voltage control signal whose leading edge corresponds to turn-on of the power source and whose trailing edge corresponds to turn-off of the power source; a leading edge delay circuit configured to receive the first voltage control signal, and to output a second voltage control signal whose leading edge is delayed by a predetermined time period relative to the leading edge of the first voltage control signal and whose trailing edge coincides with the trailing edge of the first 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, wherein, the slow turn-on circuit outputs, to the electronic switch, a switch voltage signal whose leading edge is used to control turn-on of the electronic switch and whose trailing edge is used to control turn-off of the electronic switch; a start time of the leading edge of the switch voltage signal coincides with a start time of the leading edge of the second voltage control signal, but a rate of change of the leading edge of the switch voltage signal is slower than a rate of change of the leading edge of the second voltage control signal, so that when the power source is turned on, a current flowing through the electronic switch is low enough to not be able to ruin a component through which the current flows; and the trailing edge of the switch voltage signal coincides with the trailing edge of the second voltage control signal.