Patent ID: 8130520

Claim:
A power supply apparatus comprising: a power supply unit for boosting an AC input power source and outputting the boosted power source as DC output voltage; and a power factor correction (PFC) controller for controlling a switching transistor provided for the power supply unit to suppress a harmonic current, wherein the power supply unit has a feedback/resistor for detecting feedback voltage of output voltage used when the PFC controller controls the switching transistor so that the output voltage becomes constant, wherein the PFC controller has: a drive controller for controlling the switching transistor in accordance with the feedback voltage detected by the feedback resistor; and a current correction controller for detecting a load level from the output voltage generated by the power supply unit, generating an arbitrary correction current in accordance with the load level, and supplying the correction current to the feedback resistor, wherein the lower the detected load level is, the more the current correction controller increases a current value of the correction current and supplies the current value to the feedback resistor to decrease the output voltage generated by the power supply unit, wherein the current correction controller comprises: a load detector for detecting the load level from the output voltage generated by the power supply unit; and a current corrector for generating the arbitrary correction current in accordance with the load level detected by the load detector and supplying the correction current to the feedback resistor, wherein the load detector is an error amplifier for comparing the feedback voltage detected by the feedback resistor with a reference voltage and outputting an error signal.