Patent ID: 7990670

Claim:
A protective circuit connected between a power input port and an electronic component of an electronic device, the protective circuit comprising: a field effect transistor, the field effect transistor having a gate and a drain, the drain electrically connected to an anode of the power input port, and a source electrically connected to a cathode of the power input port via the electronic component; and a detection unit, the detection unit having two spaced apart conductive pads, and one pad electrically connected to the gate and the other pad electrically connected to the cathode of the power input port, wherein when the conductive pads are connected to each other, the conductive pads having a voltage dividing function to reduce the voltage between the gate and the source to be smaller than a threshold voltage of the field effect transistor to make the field effect transistor switch to a cut-off mode; an adjustable resistor, and one end of the adjustable resistor electrically connected to the gate, and the other end of the adjustable resistor electrically connected to the drain and the anode of the power input port.