Power factor correction controller and power supply apparatus using the same

A power supply apparatus, comprising:

• an input-stage circuit, configured to convert an AC power supply into an input voltage;
• a power-stage circuit, comprising a power switch, an inductor and a diode, coupled to the input-stage circuit via the inductor and coupled to a load via the diode, wherein the power switch is switched in response to a driving signal, so as to convert the input voltage into an output voltage and provide the output voltage to the load;
• and
• a PFC controller, coupled with the input-stage circuit and the power-stage circuit and comprising:
• a driving signal generation circuit, configured to generate the driving signal to drive the power switch according to the control signal;
• and
• a zero-current prediction circuit, coupled to the driving signal generation circuit and configured to perform a capacitance charge/discharge operation according to the driving signal, the input voltage and the output voltage, so as to obtain a charge/discharge time characteristic related to a zero-current time point of the inductor, wherein the zero-current prediction circuit generates the control signal to control operation of the driving signal generation circuit according to the charge/discharge time characteristic.