Abstract: Switching loss is reduced by decreasing the switching frequency of a PFC power supply in light load condition, whereas the switching frequency is maintained high in heavy load operation. Efficiency in light load operation is thus improved without enlarging a boosting inductor and an output smoothing capacitor. A capacitor is provided in a triangular wave generating circuit and the triangular wave generating circuit outputs a triangular wave by charging and discharging this capacitor. Charging and discharging of the capacitor are controlled by an oscillation frequency control circuit output current which is input to a comparator.

Abstract: The present invention realizes stabler output voltage variable control in a power supply unit. A power supply unit capable of changing dynamic output voltage has: a first regulator for dropping down voltage by a switching method and outputting the resultant voltage to a first node; and a second regulator for dropping down the input voltage by a voltage drop and outputting the resultant voltage to the first node. In the case where a target voltage instructed by first information is larger than a predetermined threshold voltage, the power supply unit controls so that the voltage of the first node becomes the target voltage and stops supply of voltage from the second regulator. In the case where the target voltage is smaller than the predetermined threshold voltage, the power supply unit controls the second regulator so that the voltage of the first node becomes the target voltage and stops output of voltage from the first regulator.

Abstract: The present invention realizes stabler output voltage variable control in a power supply unit. A power supply unit capable of changing dynamic output voltage has: a first regulator for dropping down voltage, by a switching method and outputting the resultant voltage to a first node; and a second regulator for dropping down the input voltage by a voltage drop and outputting the resultant voltage to the first node. In the case where a target voltage instructed by first information is larger than a predetermined threshold voltage, the power supply unit controls so that the voltage of the first node becomes the target voltage and stops supply of voltage from the second regulator. In the case where the target voltage is smaller than the predetermined threshold voltage, the power supply unit controls the second regulator so that the voltage of the first node becomes the target voltage and stops output of voltage from the first regulator.

Abstract: A multi-phase transformer type DC-DC converter. In one embodiment, the multi-phase transformer type DC-DC converter includes a plurality of DC-DC converters comprising a plurality of transformers, respectively, wherein the plurality of DC-DC converters are coupled in parallel between an input and an output. A circuit is coupled to the plurality of DC-DC converters and configured to generate a plurality of clock signals for use by the plurality of DC-DC converters, respectively, wherein the plurality of clock signals are phase shifted with respect to each other.

Abstract: Switching loss is reduced by decreasing the switching frequency of a PFC power supply in light load condition, whereas the switching frequency is maintained high in heavy load operation. Efficiency in light load operation is thus improved without enlarging a boosting inductor and an output smoothing capacitor. A capacitor is provided in a triangular wave generating circuit and the triangular wave generating circuit outputs a triangular wave by charging and discharging this capacitor. Charging and discharging of the capacitor are controlled by an oscillation frequency control circuit output current which is input to a comparator.

Abstract: Switching loss is reduced by decreasing the switching frequency of a PFC power supply in light load condition, whereas the switching frequency is maintained high in heavy load operation. Efficiency in light load operation is thus improved without enlarging a boosting inductor and an output smoothing capacitor. A capacitor is provided in a triangular wave generating circuit and the triangular wave generating circuit outputs a triangular wave by charging and discharging this capacitor. Charging and discharging of the capacitor are controlled by an oscillation frequency control circuit output current which is input to a comparator.

Abstract: The present invention realizes stabler output voltage variable control in a power supply unit. A power supply unit capable of changing dynamic output voltage has: a first regulator for dropping down voltage, by a switching method and outputting the resultant voltage to a first node; and a second regulator for dropping down the input voltage by a voltage drop and outputting the resultant voltage to the first node. In the case where a target voltage instructed by first information is larger than a predetermined threshold voltage, the power supply unit controls so that the voltage of the first node becomes the target voltage and stops supply of voltage from the second regulator. In the case where the target voltage is smaller than the predetermined threshold voltage, the power supply unit controls the second regulator so that the voltage of the first node becomes the target voltage and stops output of voltage from the first regulator.

Abstract: The present invention is directed to largely improve the efficiency at the time of light load of a power supply apparatus using a power factor correction (PFC) controller. A PFC controller is provided with a voltage-current converter. The voltage-current converter converts voltage of a signal output from an error amplifier for detecting voltage level of output voltage to an arbitrary current value and outputs the current value as a correction current. The voltage-current converter outputs a correction current of a large current value when the error amplifier detects that the load is light, and the PFC controller performs control to decrease the output voltage.

Abstract: A PFC counter which controls a switching element of voltage step-up chopper circuits arranged in parallel has a circuit (SLOG) generating a switch signal (GD_S) whose phase is shifted from that of a switch signal of one of the switching elements. This circuit has a first counter (COUNTM) which counts clock signals by a cycle unit of one of the switch signals; a second counter (COUNTS) which counts clock signals by a cycle unit having a predetermined phase difference with respect to one of the switch signals; and a first register (REG1) which holds a value counted by the first counter corresponding to a high-level period of one of the switch signals.

Abstract: Switching loss is reduced by decreasing the switching frequency of a PFC power supply in light load condition, whereas the switching frequency is maintained high in heavy load operation. Efficiency in light load operation is thus improved without enlarging a boosting inductor and an output smoothing capacitor. A capacitor is provided in a triangular wave generating circuit and the triangular wave generating circuit outputs a triangular wave by charging and discharging this capacitor. Charging and discharging of the capacitor are controlled by an oscillation frequency control circuit output current which is input to a comparator.

Abstract: The present invention provides a method of improving efficiency in a full load region in a PFC power source of an active filter method by controlling a switch circuit of the PFC power source in association with an output power of the PFC power source. A pair of two switches controlling charging/discharging an inductor is provided. A MOSFET switch having a small current capacity is used as one of the switches, and an IGBT switch of a large current capacity is used as the other switch. When an output of a voltage dividing circuit for dividing voltage of an output terminal of the PFC power source is smaller than a threshold voltage, only the MOSFET switch is operated. When the output exceeds a threshold voltage, the IGBT switch is also operated.

Abstract: A PFC counter which controls a switching element of voltage step-up chopper circuits arranged in parallel has a circuit (SLOG) generating a switch signal (GD_S) whose phase is shifted from that of a switch signal of one of the switching elements. This circuit has a first counter (COUNTM) which counts clock signals by a cycle unit of one of the switch signals; a second counter (COUNTS) which counts clock signals by a cycle unit having a predetermined phase difference with respect to one of the switch signals; and a first register (REG1) which holds a value counted by the first counter corresponding to a high-level period of one of the switch signals.

Abstract: The present invention is directed to largely improve the efficiency at the time of light load of a power supply apparatus using a PFC controller. A PFC controller is provided with a voltage-current converter. The voltage-current converter converts voltage of a signal output from an error amplifier for detecting voltage level of output voltage to an arbitrary current value and outputs the current value as a correction current. The voltage-current converter outputs a correction current of a large current value when the error amplifier detects that the load is light, and the PFC controller performs control to decrease the output voltage.