Lighting power supply device

Abstract

A lighting power supply device includes a control circuit controlling a transistor that controls a drive current flown through a lamp, receiving a pulsating flow converted from an alternating current by a rectifying circuit rectifying the alternating current subjected to phase control by a phase-controlled dimmer, and generating/outputting direct current voltage/current supplied to the lamp. The control circuit includes a time-voltage conversion circuit converting a time decided according to a phase of a voltage corresponding to the pulsating flow into a voltage; and a terminal to which a capacitor with an arbitrary capacitance value is connectable. The time-voltage conversion circuit allows the capacitor to generate a charging voltage corresponding to the phase of the pulsating flow. A sample-and-hold circuit takes in the charging voltage of the capacitor at predetermined timing corresponding to a change of an output of a voltage comparison circuit, and holds/outputs the taken-in voltage until next timing.