Richtek Technology Corporation

Mao-Hui Kuo

Wei-Hsu Chang

Ta-Yung Yang

Shih-Ho Hsu

A power factor correction control circuit for correcting a power factor of a rectified power to generate an output power supplied to a load, includes: a reference voltage generator circuit generating a reference voltage according to a rectified voltage of the rectified power; and a feedback modulation circuit generating a modulation control signal based upon the reference voltage and a feedback signal related to an output voltage of the output power, to control at least one switch of a power stage circuit to switch an inductor in the power stage circuit and to thereby regulate the output voltage. The reference voltage generator circuit selects one of at least two candidate voltages as the reference voltage according to a comparison result between the rectified voltage and at least one threshold, such that the output voltage is at least partially positively correlated with the rectified voltage.

Power supply system and power factor correction control circuit and control method thereof

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.

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Taipei, Taiwan

Mao-Hui Kuo