Patent ID: 7215524

Claim:
A power source protection device comprising: a switch circuit having an input port for receiving a power form a power source and an output port for outputting the power, wherein the switching circuit further comprising a switching transistor having an emitter pole coupled to the power source, and a bias circuit coupled to the power source and providing a bias voltage to a control pole of the switching transistor to turn on the switching transistor, then passing the power through the emitter pole; an overload protection circuit coupling between the switching circuit and the power source, when a current output from the power source equal or greater than a first predetermined value, the switching circuit limiting the current below the first predetermined value, the overload protection further comprising: a detection unit for detecting the current of the power source, when the current equal or greater than a first predetermined value, output an overload signal; a first protection unit coupling to the detection unit, when the first protection unit receiving the overload signal, the first protection unit outputting a first control signal for activated the switching circuit limit the current; a short protection circuit coupling to the output port, when the output port shorted, the short protection circuit activated the switching circuit closed for stopping the power output, the short protection further comprising: a short detection unit coupled to the output port, when a short occurring in the output port of the switching circuit, the short detection unit outputting a short signal; a second protection unit coupled between the short detection unit and the bias circuit, wherein a second control signal of the second protection unit transmitted to the bias circuit, and directing the bias circuit to activate the switching circuit closed for stopping the power output.