Protection circuit for power converter

A protection circuit of a power converter, comprising:

• a switch configured to sense an input voltage of the power converter via a resistor for generating a first signal;
• a detection circuit coupled to a transformer to sense the input voltage of the power converter for generating a second signal;
• a control circuit configured to control a switching signal in response to the first signal and the second signal;
• wherein the switching signal is utilized to switching the transformer for regulating the power converter;
• a level of the first signal and the second signal is correlated to a level of the input voltage of the power converter,
• wherein the detection circuit receives the switching signal, and the second signal is generated in response to the enable of the switching signal,
• wherein when a power voltage is applied to the protection circuit, the protection circuit generates a pulse signal for over voltage protection;
• an over-voltage signal is generated when the pulse signal is at an enable state and the first signal is higher than a first threshold, wherein the over-voltage signal is coupled to disable the switching signal,
• wherein the switch is controlled by the pulse signal and is turned on in response to enablement of the pulse signal so as to generate the first signal accordingly.