Patent ID: 7474085

Claim:
An electronic device receives a start signal for the activation of power supply, comprising: a first switch unit receiving the start signal and outputting a trigger signal; a PNP transistor connected to the first switch unit and conducted by the trigger signal; a voltage divider unit connected to said PNP transistor and used to output a control bias according to a conduction current of said PNP transistor; an N-channel field effect transistor connected to said PNP transistor and said voltage divider unit, conduction of said N-channel field effect transistor being controlled by said control bias and used to maintain said PNP transistor in an on state; and a voltage clamp unit connected to said N-channel field effect transistor and providing a reference voltage to increase the level of an ON voltage of said N-channel field effect transistor; a microprocessor; and a second switch unit connected to the microprocessor, wherein the second switch receives the start signal and controls the microprocessor to turn on the N-channel field effect transistor via a third switch unit.