Abstract: A circuit board of a switching power supply device includes a positive terminal circuit pattern and a negative terminal circuit pattern that are provided on a component mount surface and respectively supply currents from input parts to two input terminals of a common mode choke coil. The positive terminal circuit pattern and the negative terminal circuit pattern are positioned in parallel and close to each other. The component mount surface of the circuit board includes a component mount surface side ground pattern arranged below the common mode choke coil. A heat dissipation ground surface of the circuit board includes a ground pattern and a plurality of heat dissipation conductor patterns. Input terminals and output terminals of the common mode choke coil are respectively electrically and thermally connected to the heat dissipation conductor patterns via through-hole conductors provided between the component mount surface and the heat dissipation ground surface.

Abstract: A noise reduction circuit includes a surface-mount common mode choke coil mounted on a circuit board. Output terminals of the common mode choke coil are connected to an input capacitor via second circuit patterns. Two terminals of the input capacitor are connected to two input ends of a switching circuit via third circuit patterns. Path lengths of the second circuit patterns are longer than path lengths of the third circuit patterns. Of a plurality of current paths, the path lengths of the third circuit patterns are shortest in comparison with path lengths of other current paths. First circuit patterns are parallel and face each other to form a first parasitic capacitance, and the second circuit patterns are parallel and face each other to form second parasitic capacitances.

Abstract: A power factor correction switching power supply device includes a power factor correction circuit connected to an alternating-current input line, a first half-bridge capacitor circuit connected between lines of the AC input line, a second half-bridge capacitor circuit connected between lines of a direct-current output line that is closer to a load than a first output capacitor, a common mode choke coil disposed between the first output capacitor and the second half-bridge capacitor circuit, and an electric path configured to electrically connect a midpoint of the first half-bridge capacitor circuit and a midpoint of the second half-bridge capacitor circuit to form a noise balancing circuit. The noise balancing circuit has a potential different from a potential of a ground and is configured to balance common mode noise.

Abstract: A switching power supply device includes an inverter circuit and a noise reduction circuit. The noise reduction circuit includes a first half-bridge capacitor circuit coupled to the DC input line, a second half-bridge capacitor circuit coupled to the AC output line, a first common-mode choke coil coupled between the first half-bridge capacitor circuit and the second half-bridge capacitor circuit, and an electrical path that electrically couples a middle point of the first half-bridge capacitor circuit with a middle point of the second half-bridge capacitor circuit.

Abstract: A switching power supply device includes power supply input lines, DC output lines, a DC-DC converter circuit, and a noise reduction circuit. The noise reduction circuit includes a first half-bridge capacitor circuit that is connected between the power supply input lines, a second half-bridge capacitor circuit that is connected between the DC output lines, a first common mode choke coil, and an electrical path. The electrical path electrically connects a midpoint of the first half-bridge capacitor circuit to a midpoint of the second half-bridge capacitor circuit.

Abstract: A switching power-supply unit includes a power conversion circuit, a control circuit, a common-mode choke coil, and half-bridge capacitors. The common-mode choke coil is connected to the control circuit on its side of a direct-current power supply. The half-bridge capacitor is connected to the power conversion circuit on its side of a direct-current power supply, and is connected to the control circuit on its side of the direct-current power supply. A midway point of the half-bridge capacitor is electrically connected to a midway point of the half-bridge capacitor. A noise balancing circuit is configured as a closed circuit including the power conversion circuit, the control circuit, the half-bridge capacitors, and the common-mode choke coil, and causes common-mode currents to be confined and canceled out each other. The common-mode currents are switching noise generated in multiple parts of the closed circuit due to a switching operation of power-conversion switching devices.

Abstract: A switching power-supply unit includes a power conversion circuit, a control circuit, a class-Y capacitor, and a common-mode choke coil. The control circuit has a direct electrical connection to the power conversion circuit. The class-Y capacitor is connected to the power conversion circuit on its side of a direct-current power supply, and is connected to the ground potential. The common-mode choke coil is connected to the control circuit on its side of a direct-current power supply. A noise balancing circuit is formed of a closed circuit including the power conversion circuit, the control circuit, the class-Y capacitor, and the common-mode choke coil. The noise balancing circuit causes common-mode currents to be confined and canceled out each other. The common-mode currents serve as switching noise generated in multiple parts of the closed circuit due to a switching operation of power-conversion switching devices.

Abstract: An inductor includes a core made from a metallic magnetic material, a wire wound around the core, a pair of outer electrodes coupled to respective end portions of the wire, a shielding member arranged so as to cover a top face and three or more side faces of the core, and an insulating member arranged between the core and the shielding member and having thermal conductivity. The thickness of the shielding member is set by applying the electric resistivity and permeability of the shielding member and the frequency of noise desired to be shielded to an expression for determining the depth of a skin of skin effect. The thickness of the insulating member is set according to the breakdown voltage of the insulating member and the voltage with which insulation is desired to be ensured under a use environment of the inductor.

Abstract: An electronic circuit includes a common mode choke coil (CMCC), a first capacitor and a second capacitor as a pair of line bypass capacitors, and a DC-DC converter coupled to a power line and also to a ground line coupled to a ground of a substrate. The first capacitor is coupled to the power line between the CMCC and the DC-DC converter. The first capacitor is coupled between the power line and a metal housing. The second capacitor is coupled to the ground line between the CMCC and the DC-DC converter. The second capacitor is coupled between the ground line and the metal housing.

Abstract: An on-board charger includes input ports, output ports, an AC-DC converter, an isolated DC-DC converter, a first filter, and a second filter. The first filter is connected to the input ports. The first filter includes a first common mode choke coil, a first across-the-line capacitor, and first line bypass capacitors. The second filter is connected between the isolated DC-DC converter and each of the output ports. The second filter includes a second common mode choke coil and second line bypass capacitors.

Abstract: An on-board charger includes input ports, output ports, an AC-DC converter, an isolated DC-DC converter, a first filter, and a second filter. The first filter is connected to the input ports. The first filter includes a first common mode choke coil, a first across-the-line capacitor, and first line bypass capacitors. The second filter is connected between the isolated DC-DC converter and each of the output ports. The second filter includes a second common mode choke coil and second line bypass capacitors.

Abstract: A signal transmission and reception element transmits and receives a differential signal. Two transmission lines transmit the differential signal between the signal transmission and reception element and a connector. The signal transmission and reception element is connected to an external apparatus with the connector interposed therebetween. A noise generation source generates noise in a wireless band, which is coupled to the transmission lines. An antenna has a gain in a frequency band of the noise which is generated in the noise generation source. A wireless signal processing circuit processes a signal received by the antenna. An absorption-type filter that is mounted on the transmission lines absorbs noise mixed in the transmission lines.

Abstract: A power supply circuit includes a DC-DC converter and a choke coil. The choke coil includes a pair of coils wound in mutually opposite directions, and the coils are connected between a DC power source and the DC-DC converter. In the choke coil, a self-resonating frequency in a common mode is higher than a self-resonating frequency in a normal mode. In the choke coil, a normal mode impedance at the highest frequency in an AM band is higher than a common mode impedance at the lowest frequency in an FM band.

Abstract: An inductor includes a core made from a metallic magnetic material, a wire wound around the core, a pair of outer electrodes coupled to respective end portions of the wire, a shielding member arranged so as to cover a top face and three or more side faces of the core, and an insulating member arranged between the core and the shielding member and having thermal conductivity. The thickness of the shielding member is set by applying the electric resistivity and permeability of the shielding member and the frequency of noise desired to be shielded to an expression for determining the depth of a skin of skin effect. The thickness of the insulating member is set according to the breakdown voltage of the insulating member and the voltage with which insulation is desired to be ensured under a use environment of the inductor.

Abstract: A signal transmission and reception element transmits and receives a differential signal. Two transmission lines transmit the differential signal between the signal transmission and reception element and a connector. The signal transmission and reception element is connected to an external apparatus with the connector interposed therebetween. A noise generation source generates noise in a wireless band, which is coupled to the transmission lines. An antenna has a gain in a frequency band of the noise which is generated in the noise generation source. A wireless signal processing circuit processes a signal received by the antenna. An absorption-type filter that is mounted on the transmission lines absorbs noise mixed in the transmission lines.

Abstract: A power supply circuit includes a DC-DC converter and a choke coil. The choke coil includes a pair of coils wound in mutually opposite directions, and the coils are connected between a DC power source and the DC-DC converter. In the choke coil, a self-resonating frequency in a common mode is higher than a self-resonating frequency in a normal mode. In the choke coil, a normal mode impedance at the highest frequency in an AM band is higher than a common mode impedance at the lowest frequency in an FM band.