Sanken Electric Co., Ltd.

Takashi Matsumoto

Masao Ueno

Mitsutomo Yoshinaga

Takeki Sugahara

Tetsuya Tabata

Mitsugu Furuya

A switching power supply device that switches setting of an output voltage based on an external signal according to one or more embodiments includes: a transformer including a primary winding and n secondary windings; n synchronous rectification elements provided, corresponding to the n secondary windings; and n&#x2212;1 switch elements that switch the secondary windings. Each of the n&#x2212;1 switch elements is kept on or off according to a high or low voltage value out of set voltages of the output voltage, and all or any of the n synchronous rectification elements are selected to synchronously rectify pulse voltage of the secondary windings, and when operation with a high set value of the output voltage stops, a synchronous rectification element used to output the high set value performs switching operation until the output voltage goes down to the low voltage value of the set voltages of the output voltage.

Switching power supply device changing output voltage setting and integrated circuit for switching power supply device

A switching power-supply device comprises: a transformer; a switching element connected in series with a primary coil; an output voltage generation circuit to generate an output voltage from a voltage generated in a secondary coil; a control circuit power-supply-voltage generation circuit to generate a power-supply voltage from a voltage generated in an auxiliary coil; a feedback control circuit to control an ON width of the switching element by using the voltage generated in the auxiliary coil; a voltage reduction detection circuit to output a pulse signal to the secondary coil when a reduction of the output voltage is detected; a voltage-reduction-signal detection circuit to detect the voltage reduction signal transmitted to the primary coil from the secondary coil; and a trigger circuit to output a trigger signal to turn on the switching element when the voltage reduction signal is detected by the voltage-reduction-signal detection circuit.

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Asaka, Japan

Takashi Matsumoto