Patent ID: 8493701

Claim:
An overvoltage protection circuit, comprising: a connection jack for connecting to a power supply to receive power from the power supply; a path connection module connected between the connection jack and a load; a voltage response module to output a first signal when overvoltage occurs, and output a second signal when overvoltage disappears; and a control module to output a corresponding potential according to the first signal to turn off the path connection module, and output a corresponding potential according to the second signal to turn on the path connection module; wherein when the path connection module is turned off, the connection between the connection jack and the load is disabled, and when the path connection module is turned on, the connection between the connection jack and the load is enabled; the control module comprises a first npn BJT, a diode, and a first resistor, the base of the first npn BJT is connected to the voltage response module, the emitter of the first npn BJT is grounded, and the collector is connected to the cathode of the diode, the anode of the diode is connected to the path connection module and connected to the anode of the power supply through the first resistor; and the path connection module comprises a second npn BJT, an n-channel metal-oxide-semiconductor filed-effect transistor (NMOSFET), and a second resistor, the base of the second npn BJT is connected to the anode of the diode and the anode input port through the first resistor, the emitter of the second npn BJT is grounded, and the collector of the second npn BJT is connected to the gate of the NMOSFET, the gate of the NMOSFET is connected to the anode of the power supply through the second resistor, the source of the NMOSFET is connected to the anode of the power supply, the drain of the NMOSFET is connected to the load.