Patent ID: 7656119

Claim:
An electric charging protection circuit in a mobile communication terminal having an installed battery, comprising: a charger integrated circuit controlling an electric charging of the installed battery with an electric charging power via an adaptor or a receptacle; a control unit deciding whether the installed battery is a correct battery by recognizing a serial number of the installed battery, the control unit outputting a control signal for controlling the electric charging according to a result of the decision; a switching circuit switching a supply of an electric charging power applied to the installed battery according to the control signal of the control unit; and an overvoltage protection circuit configured to protect the charger integrated circuit and the installed battery from an overvoltage of the electric charging power provided via the adapter or the receptacle, wherein the overvoltage protection circuit disconnects the electric charging power provided from the adaptor or the receptacle when an electric charging power voltage is greater than a predetermined voltage, wherein the overvoltage protection circuit comprises: a Zener diode turned on if the voltage of the electric charging power delivered via the adapter and/or the receptacle is greater than the predetermined voltage; a first switching transistor having a base end connected to the Zener diode to be switched by an operational voltage by the turned-on Zener diode; a second switching transistor having a gate end connected to a collector end of the first switching transistor, the second switching transistor switched according to an operational state of the first switching transistor to control the electric charging power delivered via the adaptor and/or the receptacle; and a third switching transistor having a gate end connected to a drain end of the second switching transistor to control an electric charging voltage delivered via the drain end to the charger integrated circuit and/or he battery according to an operational state of the second switching transistor.