Patent ID: 7133300

Claim:
An over-voltage protection circuit for a power converter, comprising: an oscillator, generating a clock signal; an over-voltage comparative unit, receiving a sense signal for generating a protection signal in response to compare said sense signal with a threshold signal; an accumulating trigger unit, coupled to said over-voltage comparative unit and said oscillator for generating an off signal in response to said protection signal and said clock signal, wherein said accumulating trigger unit accumulates and counts said protection signal for generating the off signal as a period of said protection signal reaches a predetermined clock count; a latch unit, coupled to said accumulating trigger unit for generating a latch signal in response to said off signal; a driving output unit, coupled to said latch unit and said oscillator for generating a switching signal in response to said clock signal and said latch signal, wherein said latch signal is used to disable said switching signal to a power switch; and a driving control unit, coupled to said driving output unit for generating a clear signal in response to said sense signal and a second threshold signal, wherein said clear signal is used to turn off said switching signal to said power switch as said sense signal is higher than said second threshold signal; wherein said latch unit controls said driving output unit for latching off said switching signal to said power switch.