Mitsumi Electric Company Ltd.

Daisuke Imade

Hiroki Matsuda

Yukio Murata

Naoto Endo

Satoshi Arima

Takumi Hyugaji

An insulated power supply apparatus includes: a transformer; a switching element connected in series with a primary-side winding of the transformer; an active clamp circuit connected between terminals of the winding; and a semiconductor device for power supply control that controls the switching element and the active clamp circuit. A current-to-voltage converter element is connected in series with the switching element. The semiconductor device includes: a circuit that generates a timing to turn off the switching element based on a voltage obtained by conversion by the converter element and a predetermined turn-off threshold level; a circuit that performs ON/OFF control of the switching element in a burst mode at a predetermined load or less; and a circuit that, in the burst mode, changes a burst frequency to be lower as a load current is smaller with the number of switching times of the switching element in one burst cycle fixed.

Insulated power supply apparatus and semiconductor device for power supply control

A power supply apparatus includes a voltage conversion circuit, a reference voltage generating circuit, a constant current control circuit which includes a current controller and a differential circuit which controls the current controller based on the reference voltage and current detection voltage showing a size of the output current, and wherein an electric current on the current path is controlled by the current controller a reference voltage adjustment circuit which adjusts a first reference voltage generated by the reference voltage generating circuit to converge a ripple occurring in the output current to a predetermined ripple rate or less, based on a voltage of a first potential point set on the current path from an output portion on a high potential side of the voltage conversion circuit to the current controller and a control voltage of the current controller.

Power supply apparatus, semiconductor integrated circuit, and ripple suppressing method

A power supply device includes a voltage conversion circuit, a current controller and a current controlling circuit. The voltage conversion circuit generates a DC voltage from an AC power source and outputs the DC voltage to a pair of output terminals. The current controller is disposed on a first current path through which an output current flows and controls the current in the first current path. The current controlling circuit drives the current controller so as to reduce a ripple component generated in the output current, based on (i) a voltage at a first potential point set on a path from an output terminal at a high-potential side of the voltage conversion circuit to the current controller in the first current path and (ii) a current detecting voltage indicating the magnitude of the output current.

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Isehara, Japan

Daisuke Imade