Abstract: A boost power factor correction circuit includes: a switch and an inductor coupled to each other; a current sensing device generating a current sensing signal according to a current flowing through the switch; a temperature sensing device coupled to the inductor to generate a temperature sensing signal; and a conversion control circuit operating the switch. The conversion control circuit is an integrated circuit and includes: a shared pin coupled to the temperature sensing device and the current sensing device; and a current sensing circuit and a temperature sensing circuit which sense a multipurpose sensing signal through the shared pin. The multipurpose sensing signal is related to the current sensing signal when the switch is ON and related to the temperature sensing signal when the switch is OFF. The temperature sensing signal is related to an input voltage, an output voltage and an electrical parameter of the temperature sensing device.

Abstract: A power supply system includes a power factor correction converter circuit and an isolated power converter circuit, wherein the power factor correction converter circuit corrects the power factor of a rectified power to generate a first output power, and the isolated power converter circuit converts the first output power to generate a second output power. The isolated power converter circuit includes a transformer, and the transformer includes a primary winding, a secondary winding, and an auxiliary winding. The auxiliary winding generates an auxiliary voltage which is related to the second output power. When the auxiliary voltage is lower than a disabled threshold, indicating that the voltage of the second output power is lower than a threshold, the power factor correction converter circuit provides a bypassing connection from the rectified power to the first output power and stops correcting the power factor of the rectified power.