Switch control circuit, power factor corrector including the same, and driving method of the power factor corrector

A switch control circuit of a power factor corrector receiving an input voltage and generating an output voltage according to a switching operation of a power switch, comprising:

• a zero crossing detection comparator comparing a zero crossing voltage to sense the voltage of both terminals of the power switch and a zero crossing reference voltage to control the turn-on time and generating the zero crossing detection signal according to the comparison result;
• and
• a frequency restriction unit generating an on control signal to turn on the power switch in synchronization with the zero crossing detection signal of an enable level after the screen period is passed,
• wherein the screen period is a period corresponding to the threshold frequency when the switching frequency of the power switch is restricted by a predetermined threshold frequency.