AC/DC voltage converting circuit with low stand-by power consumption and control method thereof

The present invention provides a low standby power AC-DC voltage conversion circuit, comprising successively parallel safety capacitor, the common mode filter inductor, the rectifier bridge, the filter circuit and the switching power supply, safety capacitor receiving input power and the input power after the common mode filter inductor, the rectifier bridge and the filter input to the post-processing switching power supply circuit, the switching power supply circuit includes a power stage circuit, control circuit, and a dummy load, a control circuit for detecting the input power supply and control is working power stage circuit for converting an input power source voltage; when the input power to the normal operation, the dummy load is removed; when the input supply undervoltage locked working state, the dummy load is loaded to perform the safety capacitor discharge work. The present invention solves the problems of the prior art was added directly to the power loss caused by the discharge resistor, reducing the cost of the switch, while beneficial to the IC.