Patent ID: 7639465

Claim:
An inrush current restraining circuit, comprising: a power source; a charging/discharging circuit connected to the power source, comprising: a PNP transistor; wherein a base of the PNP transistor is connected to the power source, and a collector of the PNP transistor is connected to the input of the switching circuit; a first resistor connected between the base and an emitter of the PNP transistor, for providing a bias voltage; a second resistor; a capacitor connected to the second resistor in series; and a third resistor connected between the collector of the PNP transistor and ground, wherein the second resistor and the capacitor are connected between the emitter of the PNP transistor and ground; a switching circuit, wherein an input of the switching circuit is connected to the charging/discharging circuit, and an output of the switching circuit is defined as an output of the inrush current restraining circuit; a first impedance component, wherein one end of the first impedance component is connected to the power source; a second impedance component connected between the other end of the first impedance and the switching circuit; and a controller connected to a joint of the first impedance component and the second impedance component, for providing a control signal.