Abstract: A PFC converter that reduces a superimposed voltage generated by an inrush current into a filter capacitor operates such that, when a commercial alternating-current power supply is connected to input terminals of a PFC converter, a rectified voltage is applied to a filter capacitor via a diode bridge and a charging current flows through the filter capacitor. At the same time, the rectified voltage is also applied to a series circuit including a diode and a capacitor and a charging current for the capacitor flows through the series circuit. Accordingly, a charging time constant becomes large and a superimposed voltage generated by the inductance component of a line or a line filter connected to the line and the charging current becomes low.

Abstract: An LED driving power supply apparatus and an LED lighting apparatus is provided in which stable dimming is realized even when dimming is performed in a range that includes a light-off state. A power conversion control circuit controls the on time or switching period of a switching device in accordance with a feedback control signal input through an insulating member, operates as a PFC converter, and controls power supplied to the LED. A dimming control circuit includes a constant current control circuit, a constant voltage control circuit, and an OR gate circuit. When the external dimming signal is a signal specifying normal lighting, the constant current control circuit maintains a current supplied to the LED at a target current. When the external dimming signal is a signal specifying a minimum luminance, the constant voltage control circuit maintains a voltage applied to the LED at a target voltage.

Abstract: A PFC converter that reduces a superimposed voltage generated by an inrush current into a filter capacitor operates such that, when a commercial alternating-current power supply is connected to input terminals of a PFC converter, a rectified voltage is applied to a filter capacitor via a diode bridge and a charging current flows through the filter capacitor. At the same time, the rectified voltage is also applied to a series circuit including a diode and a capacitor and a charging current for the capacitor flows through the series circuit. Accordingly, a charging time constant becomes large and a superimposed voltage generated by the inductance component of a line or a line filter connected to the line and the charging current becomes low.