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Switching power supply device

  • US 9,257,912 B2
  • Filed: 09/09/2014
  • Issued: 02/09/2016
  • Est. Priority Date: 03/30/2012
  • Status: Active Grant
First Claim
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1. A switching power supply device, comprising:

  • a power supply voltage inputting unit configured to accept input of an input power supply voltage;

    a direct current voltage outputting unit configured to output a direct current voltage;

    a transformer including a primary winding and a secondary winding that are wound around a winding portion of a bobbin, a low side drive winding, a high side drive winding, and a core defining a closed magnetic circuit;

    a capacitor that defines an LC resonant circuit including the primary winding;

    a series circuit that is connected to the power supply voltage inputting unit and that includes a low side switching element and a high side switching element; and

    a switching controlling circuit that includes a low side switching controlling unit configured or programmed to control the low side switching element and a high side switching controlling unit configured or programmed to control the high side switching element;

    whereinthe LC resonant circuit includes a leakage inductance of the primary winding or the secondary winding of the transformer;

    the low side switching element is connected to the primary winding in series and is configured to apply a voltage of the power supply voltage inputting unit to the primary winding upon being turned on;

    the low side switching controlling unit is configured or programmed to turn on the low side switching element upon detecting a reversal of a polarity of a winding voltage generated in the low side drive winding and turn off the low side switching element at a timing that is based on a feedback signal of a circuit that detects an output voltage;

    the high side switching controlling unit is configured or programmed to turn on the high side switching element upon detecting a reversal of a polarity of a winding voltage generated in the high side drive winding and turn off the high side switching element in accordance with an on time of the low side switching element;

    the bobbin includes a partition portion that includes a slit;

    the partition portion is provided along an outer periphery of the winding portion and divides the winding portion into a first winding area in which the primary winding is wound and a second winding area in which the secondary winding is wound;

    the primary winding is wound to a first height h1 from the outer periphery of the winding portion;

    the secondary winding is wound to a second height h2 from the outer periphery of the winding portion; and

    the low side drive winding and the high side drive winding are wound on the primary winding so as to be next to each other in a winding axis direction with the high side drive winding located toward the secondary winding.

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