Abstract: A determination circuit including a detection circuitry, a switch controller, and a determination circuitry. The detection circuitry is configured to detect that an overvoltage has occurred in an electric power supply path. The switch controller is configured to turn off a switch when the detection circuitry has detected that the overvoltage has occurred. The determination circuitry is configured to perform a determination operation including determining whether the overvoltage that has occurred is attributed to an electric power conversion circuit or a load, on a basis of one of or both a first voltage of a first path and a second voltage of a second path that are in a period in which the switch is off, the first path coupling the switch and the electric power conversion circuit in the electric power supply path, the second path coupling the switch and the load in the electric power supply path.

Abstract: A determination circuit including a detection circuitry, a switch controller, and a determination circuitry. The detection circuitry is configured to detect that an overvoltage has occurred in an electric power supply path. The switch controller is configured to turn off a switch when the detection circuitry has detected that the overvoltage has occurred. The determination circuitry is configured to perform a determination operation including determining whether the overvoltage that has occurred is attributed to an electric power conversion circuit or a load, on a basis of one of or both a first voltage of a first path and a second voltage of a second path that are in a period in which the switch is off, the first path coupling the switch and the electric power conversion circuit in the electric power supply path, the second path coupling the switch and the load in the electric power supply path.

Abstract: A power supply device 1 includes a main circuit board 20, a power component 22 connected to the main circuit board 20, a filter component 24 connected to the main circuit board 20, and a casing 10 which houses the main circuit board 20, the power component 22, and the filter component 24. The casing 10 includes a base plate 11 which includes a flat surface 11a in which a fin 14 for heat dissipation is provided on a bottom-surface side, and a protruding part 15 which protrudes from the flat surface toward the fin. The power component 22 and the main circuit board 20 are placed on the flat surface, and the filter component 24 is housed in the protruding part 15.

Abstract: A switching power supply device includes a switching power supply circuit and a control circuit. The switching power supply circuit includes a transformer having a primary winding and a secondary winding, a switching circuit coupled to the primary winding, and a conversion circuit that is coupled to the secondary winding and converts an alternating current voltage outputted from the secondary winding into a direct current voltage. The control circuit determines a maximum load current value on a basis of a duty ratio in the conversion circuit and the direct current voltage, and controls, on a basis of the maximum load current value, an operation of the switching circuit to cause the switching power supply circuit to perform a predetermined voltage reduction operation. The maximum load current value indicates a maximum value of a load current that allows the conversion circuit to output a predetermined voltage.

Abstract: A power supply device 1 includes a main circuit board 20, a power component 22 connected to the main circuit board 20, a filter component 24 connected to the main circuit board 20, and a casing 10 which houses the main circuit board 20, the power component 22, and the filter component 24. The casing 10 includes a base plate 11 which includes a flat surface 11a in which a fin 14 for heat dissipation is provided on a bottom-surface side, and a protruding part 15 which protrudes from the flat surface toward the fin. The power component 22 and the main circuit board 20 are placed on the flat surface, and the filter component 24 is housed in the protruding part 15.