Rossi, Kimms & McDowell LLP
Switching power supply device
In some aspects of the invention, a load state detecting circuit is configured so that a threshold voltage for determining the size of a load of a DC-DC converter is set in the load state detecting circuit based on a maximum value of an output voltage of a power factor correction converter in an operation-stopped state of the power factor correction converter, so that the load state detecting circuit outputs an operation-enable signal when a feedback voltage indicating the size of the load of the DC-DC converter exceeds the threshold voltage. Thus, by way of some aspects of the invention, it is possible to provide a switching power supply device which can control enabling and stopping operation of a power factor correction converter reliably in accordance with a load state of a DC-DC converter obtaining a predetermined DC output voltage by switching an output voltage of the correction converter.
FUJI ELECTRIC CO., LTD.
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Jian
Chen