Abstract: A power supply device according to an embodiment may include: a voltage generator configured to generate, from a commercial power supply, a first voltage and a second voltage lower than the first voltage; a voltage step-down part configured to decrease the first voltage to the second voltage; a bypass part configured to output the second voltage output from the voltage generator, with the voltage step-down part bypassed; and a controller configured, in a normal operation mode, to cause the voltage generator to generate and output the first voltage and to cause the voltage step-down part to operate and decrease the first voltage to the second voltage and output the second voltage, and configured, in a power-saving mode, to cause the voltage generator to generate the second voltage and output the second voltage through the bypass part without causing the voltage step-down part to operate.

Abstract: A power supply device according to an embodiment may include: a voltage generator configured to generate, from a commercial power supply, a first voltage and a second voltage lower than the first voltage; a voltage step-down part configured to decrease the first voltage to the second voltage; a bypass part configured to output the second voltage output from the voltage generator, with the voltage step-down part bypassed; and a controller configured, in a normal operation mode, to cause the voltage generator to generate and output the first voltage and to cause the voltage step-down part to operate and decrease the first voltage to the second voltage and output the second voltage, and configured, in a power-saving mode, to cause the voltage generator to generate the second voltage and output the second voltage through the bypass part without causing the voltage step-down part to operate.

Abstract: A power supply device includes a rectification circuit that is supplied with AC power from an AC power supply, a power factor improvement circuit that boosts an output voltage of the rectification circuit, smooths a boosted voltage with a capacitor, and thereby generates a DC output voltage outputted to a load circuit, a DC-DC converter that steps down the DC output voltage to a prescribed first voltage, a DC output voltage detection circuit that detects whether or not the DC output voltage satisfies a prescribed condition, and a switch circuit that temporarily puts the power factor improvement circuit in an operating state by use of the first voltage each time the prescribed condition is satisfied in a period in which the power factor improvement circuit is in a stopped state due to an energy saving mode of the load circuit.

Abstract: A power supply device includes a rectification circuit that is supplied with AC power from an AC power supply, a power factor improvement circuit that boosts an output voltage of the rectification circuit, smooths a boosted voltage with a capacitor, and thereby generates a DC output voltage outputted to a load circuit, a DC-DC converter that steps down the DC output voltage to a prescribed first voltage, a DC output voltage detection circuit that detects whether or not the DC output voltage satisfies a prescribed condition, and a switch circuit that temporarily puts the power factor improvement circuit in an operating state by use of the first voltage each time the prescribed condition is satisfied in a period in which the power factor improvement circuit is in a stopped state due to an energy saving mode of the load circuit.