Mitsumi Electric Company Ltd.

Takashi Okubo

Yuji Yamanaka

Yukio Murata

Taro Isogai

A control circuit that controls a switching element includes a first terminal to which a voltage produced by conversion of current flowing through the switching element by a current-to-voltage conversion element is input, a second terminal to which the voltage of a point of contact of an inductor and rectification element or a voltage proportional thereto is input, a filter for smoothing the voltage input into the second terminal, and a voltage comparison circuit for comparing the voltage smoothed by the filter and the voltage input into the second terminal. The control circuit performs control such that the switching element is switched from off to on near the point where the inductor current becomes zero based on the voltage comparison circuit output and the switching element is switched from on to off in response to the voltage applied to the first terminal reaching a prescribed voltage.

Non-isolated power supply device

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.

Lighting power supply device

A lighting power supply device receives a voltage converted from an alternating current to a direct current by a rectifying circuit rectifying the alternating current whose phase is controlled by a phase control type dimmer, and generates and outputs a direct current voltage/current to be supplied to a load. The lighting power supply device includes: a control circuit, and the control circuit gradually decreases a current drawn from the rectifying circuit from a predetermined current value set in advance, determines a current value immediately before detecting a malfunction of the phase control type dimmer as a drawn current value, and performs current control so as to maintain the determined current value.

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Tama, Japan

Takashi Okubo