Patent ID: 8531810

Claim:
An electronic device comprising: a function module; an input port, configured for connecting to a power source and receiving power from the power source, and powering the function module using the received power, the input port comprising an anode input terminal and a cathode input terminal; and an over-current protection circuit comprising: a path switch comprising a PMOSFET and a first resistor, wherein a source of the PMOSFET is connected to the anode input terminal, a drain of the PMOSFET is connected to an anode terminal of the function module, and the first resistor is connected between the source and a gate of the PMOSFET; a current detection circuit, the current detection circuit and the path switch forming a loop with the input port and the function module, the current detection circuit being configured for detecting a value of a current of the loop, and producing a first control signal when detecting the current of the loop is equal to or greater than a predetermined current value, wherein, the current detection circuit comprises a detection resistor which is connected between the cathode input terminal of the input port and a cathode terminal of the function module; a conductor switch; a first control module, configured for turning off the conductor switch when receiving the first control signal, wherein, the first control module comprises a first optical coupler, a first voltage port, a second resistor, and a third resistor, the first optical coupler comprises a first input terminal, a second input terminal, a first output terminal, and a second output terminal, the first input terminal is connected to an end of the detection resistor and the cathode terminal of the function module, the second input terminal is connected to the other end of the detection resistor and the cathode input terminal of the input port; the first output terminal is connected to the first voltage port via the second resistor and the conductor switch via the third resistor, and the second output terminal is connected to ground; and a second control module, configured for turning off the path switch when the conductor switch is turned off, thereby cutting off the loop.