Abstract: According to one embodiment, there is provided a power supply circuit including a power conversion unit, a current regulator, a controller, and a controller power supply. The power conversion unit converts an AC voltage with a controlled conduction angle into a different voltage. The current regulator includes a branch path electrically connected to the power supply path and switches between a first state in which a part of a current flowing through the power supply path flows to the branch path and a second state in which a current flowing to the branch path is lower than that of the first state. The controller switches the current regulator to the second state in at least a part of a conduction period of a detected conduction angle and switches the current regulator to the first state in a blocking period of the detected conduction angle.

Abstract: According to one embodiment, a power supply circuit includes: a DC-DC converter which converts a first DC voltage supplied from a power supply flow path into a second DC voltage having a different absolute value, to supply the voltage to a DC load; and an overcurrent protection unit which is electrically connected to an end portion of the DC load on a low potential side, and performs feedback control of the DC-DC converter based on current which flows to the DC load. The DC-DC converter includes a normally-on type switching element. The overcurrent protection unit is electrically connected to the third electrode. When the current which flows to the DC load is greater than a reference value, the overcurrent protection unit changes the state of the switching element from the first state to the second state by decreasing the potential of the third electrode.

Abstract: According to one embodiment, a lighting light source including a current control element and a voltage-dividing resistor is provided. The current control element has a first main electrode, a second main electrode series-connected with respect to a lighting light source, and a first control electrode for controlling a current flowing between the first main electrode and the second main electrode, and controls a current supplied to the lighting light source. The voltage-dividing resistor is parallel-connected with respect to the lighting light source and connected to the first control electrode, and inputs a voltage obtained by division of a voltage of the lighting light source to the first control electrode.

Abstract: According to one embodiment, a detection circuit including first and second comparators and a determining unit is provided. The first comparator includes a first input terminal for inputting a first detection voltage, a second input terminal for inputting a first threshold voltage, and a first output terminal configured to output a first output signal. The second comparator includes a third input terminal for inputting a second detection voltage, a fourth input terminal for inputting a second threshold voltage higher than the first threshold voltage, and a second output terminal configured to output a second output signal. The determining unit is configured to determine the presence or absence of conduction angle control of an AC voltage and whether the conduction angle control is a phase control system or an opposite phase control system on the basis of a time difference between the first output signal and the second output signal.

Abstract: According to one embodiment, there is provided a power-supply circuit including a substrate, a chopper circuit, a conductive member, first capacitative elements, and second capacitative elements. The substrate includes a mounting surface. The chopper circuit is provided on the mounting surface, includes input ends, output ends, and a switching element, and converts a voltage input from the input ends and outputs the voltage from the output ends according to switching driving of the switching element. The conductive member is adjacent to at least a part of the chopper circuit. The first capacitative elements are electrically connected between the input ends and the conductive member and capacitively couple the input ends and the conductive member. The second capacitative elements are electrically connected between the output ends and the conductive member and capacitively couple the output ends and the conductive member.

Abstract: According to one embodiment, a power supply for lighting includes a rectifying circuit, a smoothing capacitor, and a current control circuit. The rectifying circuit rectifies a phase-controlled alternating-current voltage supplied to between a pair of input terminals. The smoothing capacitor is connected to a high-potential terminal and a low-potential terminal of the rectifying circuit. A first electric current flows to the current control circuit in a period when an absolute value of the alternating-current voltage is lower than a specified value. After a second electric current larger than the first electric current flows when the absolute value of the alternating-current voltage increases to be equal to or larger than the specified value, the current control circuit is shut off to reduce a current value to be smaller than the second electric current until the absolute value of the alternating-current voltage decreases to be lower than the specified value.

Abstract: A lighting power source according to an embodiment includes a rectifying circuit, a smoothing capacitor, a reference voltage generating circuit, and a DC-DC converter. The rectifying circuit rectifies an AD voltage input thereto. The smoothing capacitor smoothes an output from the rectifying circuit. The reference voltage generating circuit generates a reference voltage on the basis of at least any one of an output voltage of the rectifying circuit and a voltage from the smoothing capacitor. The DC-DC converter includes an output element and a constant current element, and converts the voltage of the smoothing capacitor. The output element receives a supply of a voltage of the smoothing capacitor, oscillates by performing a switching operation which repeats an ON state and an OFF state when the reference voltage is relatively high, and continues the ON state when the reference voltage is relatively low.

Abstract: According to one embodiment, an LED lighting device comprises at least one normally-on type switching element, an output generation unit that generates DC output by an on-off operation of the switching element, a semiconductor light emitting element that is lit by the DC output generated by the output generation unit, and a driving control unit that causes the switching element to perform an off operation using a current passed through the semiconductor light emitting element.

Abstract: According to one embodiment of the invention, there is provided a switching power supply device including a rectifying circuit and a switching operation conversion circuit. The rectifying circuit receives a phase-controlled alternating voltage to rectify to a direct voltage. The switching operation conversion circuit starts up by being applied with the direct voltage, and includes a normally on type switching element and an off driving circuit. The normally on type switching element passes an input current, and the off driving circuit turns off the switching element when the input current reaches a prescribed value. The switching operation conversion circuit converts the direct voltage to an output voltage different from the direct voltage by repeating a switching operation of turning on and off the switching element.

Abstract: A switching power supply includes a switching element, a constant current element, a rectifying element, a first inductor, a second inductor, and a control circuit. If the switching element is on, the switching element supplies a power supply voltage to the first inductor and feeds an electric current. The constant current element turns off the switching element if the electric current of the switching element exceeds a predetermined upper limit. The rectifying element feeds the electric current of the first inductor if the switching element is turned off. The second inductor supplies the induced potential to a control terminal of the switching element. The control circuit supplies a pulse-like potential to a control terminal of the constant current element and outputs if an average of the potential is lower than a lower limit.

Abstract: A switching power source includes first and second inductors, a switching element, current control element, rectifier element, and control circuit. The switching element supplies a power source voltage to the first inductor. The current control element detects a current flowing in the switching element and has first and second main terminals, and a control terminal, with the second main terminal connected to the switching element. The control circuit turns off the current control element and interrupts the current flowing in the switching element when a voltage between the second main terminal and the first main terminal of the current control element is equal to or higher than a specified value. The rectifier circuit is series-connected to one of the switching element and the current control element. The second inductor is magnetically coupled to the first inductor, in which a potential turning on and off the switching element can be induced.

Abstract: Electrical equipment includes a switching power source, a rectifier circuit, a pair of capacitative elements, and a load. The switching power source outputs an alternating-current voltage with input of a direct-current or an alternating-current power source voltage. The pair of capacitative elements are connected between the switching power source and the rectifier circuit and insulate the switching power source and the rectifier circuit. The load is connected as a load circuit to an output of the rectifier circuit and driven by a constant current.

Abstract: An integrated switching power supply device includes a series-connected body, a driving control element, and external terminals. In the series-connected body, a switching element, a constant current element, and a diode are connected in series. The driving control element controls to drive the constant current element. The external terminals include first to seventh external terminals. The first and second external terminals are connected to main terminals of elements of the series-connected body. The third external terminal is connected to a connection point of main terminals of the switching element or the constant current element and a main terminal of the diode. The fourth external terminal is connected to a control terminal of the switching element. The fifth external terminal supplies electric power to the driving control element. The sixth external terminal inputs reference potential. The seventh external terminal inputs a signal to the driving control element.

Abstract: There is provided a power supply circuit including a power converting unit, a control unit, and a power supply unit for control. The power converting unit converts a conduction angle controlled alternating-current voltage supplied via a power supply path so as to be supplied to a load. The control unit detects a conduction angle of the alternating-current voltage and controls conversion of a voltage by the power converting unit according to the detected conduction angle. The power supply unit for control is electrically connected to the power supply path and converts the alternating-current voltage so as to be supplied to the control unit.

Abstract: A power supply circuit includes a power converting unit, a current adjusting unit, and a control unit. The power converting unit is configured to convert an alternating-current voltage into a direct-current voltage and supply the direct-current voltage to a load. The alternating-current voltage is subjected to conduction angle control and is supplied via a power supply path. The current adjusting unit includes a branch path electrically connected to the power supply path and can switch a first path state and a second path state. The first path state feeds a part of an electric current flowing through the power supply path to the branch path. The control unit detects a conduction angle of the alternating-current voltage, controls the conversion of the direct-current voltage by the power converting unit according to the detected conduction angle, and controls the current adjusting unit according to the detected conduction angle.

Abstract: A switching power supply includes a transformer, a resonant capacitor, a pair of switching elements, an inductor, and a rectifying element. The transformer includes a first winding, a second winding, and a third winding. The resonant capacitor is connected to both ends of the first winding. The switching elements are normally-on elements and alternately turned off according to a voltage induced in the third winding. Each of the switching elements includes a first main terminal, a second main terminal, and a control terminal. The inductor supplies a direct-current power supply voltage between the middle point of the first winding and the each first main terminal of the switching elements. The rectifying element rectify a voltage induced in the second winding.

Abstract: A switching power supply includes a first switching element, a rectifying element, a first inductor and a second inductor. The first switching element supplies a power supply voltage to the first inductor and al lows a current to flow when the first switching element is on. The rectifying element is connected in series to the first switching element, and allows a current of the first inductor to flow when the first switching element is turned off. The second inductor is electromagnetically coupled to the first inductor, a potential to turn on the first switching element is induced when the current of the first inductor increases, and a potential to turn off the first switching element is induced when the current of the first inductor decreases. The induced potential is supplied to a control terminal of the first switching element. The rectifying element includes a diode and a second switching element.

Abstract: According to one embodiment, an LED lighting device comprises at least one normally-on type switching element, an output generation unit that generates DC output by an on-off operation of the switching element, a semiconductor light emitting element that is lit by the DC output generated by the output generation unit, and a driving control unit that causes the switching element to perform an off operation using a current passed through the semiconductor light emitting element.

Abstract: A power supply apparatus of an embodiment includes a first filter, a second filter, and a switching power supply. The first filter and the second filter attenuate a common mode current to a level lower than a normal mode current. The switching power supply is connected between the first filter and the second filter, and supplies electric power to an illumination load via the second filter.

Abstract: According to one embodiment, a power supply device includes a switching circuit and a control circuit. The switching circuit adjusts, according to ON-OFF control for an input voltage, electric power supplied to a lighting load. The control circuit controls ON and OFF of the switching circuit such that the electric power supplied to the lighting load coincides with target power. The control circuit that operates at a frequency equal to or higher than a switching frequency of the switching circuit is used. That is, a control frequency of the control circuit for the switching circuit is equal to or higher than the switching frequency of the switching circuit.