Protection circuit for power converter

摘要

A protection circuit of a power converter without an input capacitor is disclosed. The protection circuit comprises a high voltage switch, a detection circuit and a control circuit. The switch senses an input voltage of the power converter via a resistor for generating a first signal. The detection circuit coupled to a transformer senses the input voltage of the power converter for generating a second signal. The control circuit controls a switching signal in response to the first signal and the second signal. The switching signal is utilized to switching the transformer for regulating the power converter; and the level of the first signal and the second signal is correlated a level of the input voltage of the power converter.

主权项

1. 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.