Circuit with protective circuit for correcting active power factor

The invention discloses an active power factor correcting circuit with the protective circuit, at least comprising a controlled switch and a power factor control chip for real-time controlling the on and off of the controlled switch, also comprising a voltage detecting circuit, for obtaining the voltage sample from the rectified DC bus voltage or a control voltage, and outputting the voltage sample to the power factor control chip; a voltage sample upper limit corresponding to the DC bus voltage or the normal range upper limit is arranged in the power factor control chip. When the voltage sample obtained through the voltage detecting circuit is higher than the upper limit of the voltage sample, the DC bus voltage or the control voltage is overhigh, then the lower factor control chip stops controlling the on/off of the controlled switch. The preferred embodiment of the invention furthermore provides an active power factor correcting circuit with other type of protective circuits. The circuit of the invention can prolong the service life of the circuit device.