| 主权项 |
1. An overvoltage protection circuit, comprising:
a voltage boost circuit, for boosting an input voltage into an output voltage in need and providing the output voltage to a load; a voltage control module, for controlling the voltage boost circuit to boost an input voltage into an output voltage in need and for providing the output voltage to the load and to drive the load in a constant current; an overvoltage protection module, for monitoring a voltage of a positive terminal of the load and generating a control signal based on the voltage of the positive terminal of the load and a predetermined overvoltage, the control signal being used to control the voltage control module to enable or disable; and an overvoltage adjusting module, for monitoring an operation voltage of the load to generate an adjustment signal according to the operation voltage, the adjustment signal being used for adjusting an overvoltage in the overvoltage protection module; wherein the overvoltage protection module generates a first control signal to control the voltage control module to enable if the overvoltage protection module monitors that the voltage of the positive terminal of the load is under the overvoltage of the overvoltage protection module, and the overvoltage protection module generates a second control signal to control the voltage control module to disable if the overvoltage protection module monitors that the voltage of the positive terminal of the load is over the overvoltage of the overvoltage protection module; wherein if the overvoltage adjusting module monitors the operation voltage in the load is under a standard value, the overvoltage adjusting module generates a first adjustment signal, and the overvoltage protection module decreases the overvoltage according to the first adjustment signal, and if the overvoltage adjusting module monitors the operation voltage in the load is over the standard value, the overvoltage adjusting module generates a second adjustment signal, and the overvoltage protection module augments overvoltage according to the second adjustment signal; wherein the overvoltage protection module comprises an adjustment circuit for adjusting overvoltage according to an adjustment signal from the overvoltage adjusting module, and a protection circuit for monitoring and comparing a voltage of the positive terminal of the load with the overvoltage to generate a control signal coupling to the voltage control module; wherein the adjustment circuit comprises a first voltage regulator, a second voltage regulator, a third voltage regulator, a first field-effect transistor, a second field-effect transistor, a third field-effect transistor and a third resistor; and wherein the first voltage regulator, the second voltage regulator and the third voltage regulator are in electrical series, a cathode of the first voltage regulator is coupled to the protection circuit, an anode of the third voltage regulator is grounded; gates of the first and the second field-effect transistors are respectively coupled to the overvoltage adjusting module, the adjustment signal from the overvoltage adjusting module controls the first field-effect transistor and the second field-effect transistor to turn on or off, a drain of the first field-effect transistor is coupled to a cathode of the first voltage regulator, a drain of the second field-effect transistor is coupled to a gate of the third field-effect transistor and then coupled to a third reference voltage through the third resistor, a drain of the third field-effect transistor is coupled to an anode of the second voltage regulator, sources of the first, the second and the third field-effect transistors are all grounded; and the protection circuit comprises a fourth resistor and a fourth field-effect transistor, one end of the fourth resistor is coupled to a positive end of the load, the other end of the fourth resistor is coupled to a gate of the fourth field-effect transistor and then coupled to the cathode of the first voltage regulator, a drain of the fourth field-effect transistor outputs a control signal coupling to the voltage control module, and a source of the fourth field-effect transistor is grounded. |
