Switching power-supply device
AssigneeSanken Electric Co., Ltd.
InventorMasaru Nakamura
Life of this patent
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Abstract
A switching power-supply device configured to convert and output a first direct voltage supplied from an input power source to a second direct voltage by alternately turning on and off a first switching element connected to the input power source and a second switching element connected in series to the first switching element, the switching power-supply device includes a reference voltage generation unit; and a driving unit, wherein when a generation cycle of a timing becomes shorter than a first cycle, a reference voltage generation unit cause a slope of a ramp signal, which is to be superimposed with a first reference voltage, to become gentler than a case where a generation cycle of a timing is equal to or longer than the first cycle.
Claims8
A switching power-supply device configured to convert and output a first direct voltage supplied from an input power source to a second direct voltage by alternately turning on and off a first switching element connected to the input power source and a second switching element connected in series to the first switching element, the switching power-supply device comprising:
- a reference voltage generation unit configured to generate a second reference voltage in which a ramp signal is superimposed with a first reference voltage;
- a driving unit that turns the first switching element from off to on synchronous with a timing, at which a feedback voltage obtained by resistance voltage dividing of the second direct voltage becomes lower than the second reference voltage;
- a comparison unit that compares the feedback voltage with the second reference voltage and outputs an effective signal at the timing;
- and
- a driving signal generation unit that receives the effective signal and supplies a driving signal for turning on the first switching element to the driving unit, wherein the driving unit turns on the first switching element during a period in which the driving signal is supplied;
- wherein the reference voltage generation unit comprises:
- a capacitor configured to generate the ramp signal;
- a superimposing unit that overlaps a voltage accumulated in the capacitor, as the ramp signal, with the first reference voltage;
- and
- a charging-and-discharging unit that discharges the capacitor by receiving the driving signal and charges the capacitor until the driving signal is subsequently received,
- wherein when a load current of the second direct voltage is switched from a light load to a heavy load and a generation cycle of the timing becomes shorter than a first cycle, the reference voltage generation unit causes a slope of the ramp signal, which is to be superimposed with the first reference voltage, to become smaller than the slope of the ramp signal in a case where the generation cycle of the timing is equal to or longer than the first cycle.
A switching power-supply device configured to convert and output a first direct voltage supplied from an input power source to a second direct voltage by alternately turning on and off a first switching element connected to the input power source and a second switching element connected in series to the first switching element, the switching power-supply device comprising:
- a feedback voltage generation unit configured to generate a feedback voltage in which a negatively-sloped ramp signal is superimposed with a voltage obtained by resistance voltage dividing of the second direct voltage;
- a driving unit that turns the first switching element from off to on synchronous with a timing, at which the feedback voltage becomes lower than a reference voltage;
- a comparison unit that compares the reference voltage with the feedback voltage and outputs an effective signal at the timing;
- a driving signal generation unit that receives the effective signal and supplies a driving signal for turning on the first switching element to the driving unit,
- wherein the driving unit turns on the first switching element during a period in which the driving signal is supplied, and
- wherein the feedback voltage generation unit comprises:
- a capacitor configured to generate the ramp signal;
- a superimposing unit that overlaps a voltage accumulated in the capacitor, as the negatively-sloped ramp signal, with the feedback voltage;
- and
- a charging-and-discharging unit that discharges the capacitor by receiving the driving signal and charges the capacitor until the driving signal is subsequently received,
- wherein when a generation cycle of the timing becomes shorter than a first cycle, the feedback voltage generation unit causes a slope of the negatively-sloped ramp signal, which is to be superimposed with the voltage, to become smaller than the slope of the negatively-sloped ramp signal in a case where the generation cycle of the timing is equal to or longer than a first cycle.
Dependencies are inferred from the claim text.