Power factor corrected SMPS with light and heavy load control modes
AssigneeSanken Electric Co., Ltd.
InventorsTomoyasu Yamada, Masaaki Shimada
Life of this patent
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Abstract
In the switching power supply, a load state judgment circuit (25) judges the state of a load (20) according to a pulse signal VG to be used for ON/OFF control of a MOS transistor (8) as a switching element in a DC—DC converter (127). In order to reduce a power consumption of the switching power supply, a PFC ON/OFF switching circuit (24) stops the operation of the power factor improving converter (126) when the judgment result indicates a light load state, and starts the operation of the power factor improving converter (126) when the judgment result indicates a heavy load state.
Claims9
A switching power supply comprising:
- a power factor improving converter comprising a first switching element converting an alternating current (AC) voltage to a direct current (DC) voltage which is greater in voltage level than that of the AC voltage by performing a ON/OFF control for the first switching element;
- a DC—DC converter comprising a second switching element converting the DC voltage from the power factor improving converter to a DC voltage by performing a ON/OFF control for the second switching element;
- and
- a control section judging a load state according to a pulse signal to be used for performing the ON/OFF control for the second switching element, and stopping the operation of the power factor improving converter when the judgment result indicates a light load state, and starting the operation of the power factor improving converter when the judgment result indicates a heavy load state which is rather in load than the light load state.
Dependencies are inferred from the claim text.