Abstract: A power supply circuit of a step-down type, configured to generate an output voltage at a predetermined level from an alternating current (AC) voltage. The power supply circuit includes a rectifier circuit configured to rectify the AC voltage, a first line coupled to the rectifier circuit, a second line on a ground side, a switch coupled between the first line and the second line, and a control circuit configured to control the switch to bring a level of the output voltage to the predetermined level. The power supply circuit is free of an inductor interposed between the first line and the rectifier circuit.

Abstract: A control circuit for a circuit that has a rectifier circuit including first to fourth diodes, and first to fourth switches respectively connected in parallel with the first to fourth diodes, for rectifying an AC voltage; and a capacitor receiving the rectified AC voltage. The control circuit controls the first to fourth switches, and includes: a determination unit determining an off-period in which, when the AC voltage is applied, the first to fourth diodes turn off, the off-period including a first period and a second period, in which the first and fourth diodes, and the second and third diodes, respectively turn off; and a control unit turning on the first and fourth switches in the first period, when the second and third diodes are off, and turning on the second and third switches in the second period, when the first and fourth diodes are off.

Abstract: A control circuit for a circuit that has a rectifier circuit including first to fourth diodes, and first to fourth switches respectively connected in parallel with the first to fourth diodes, for rectifying an AC voltage; and a capacitor receiving the rectified AC voltage. The control circuit controls the first to fourth switches, and includes: a determination unit determining an off-period in which, when the AC voltage is applied, the first to fourth diodes turn off, the off-period including a first period and a second period, in which the first and fourth diodes, and the second and third diodes, respectively turn off; and a control unit turning on the first and fourth switches in the first period, when the second and third diodes are off, and turning on the second and third switches in the second period, when the first and fourth diodes are off.

Abstract: A power supply circuit of a step-down type, configured to generate an output voltage at a predetermined level from an alternating current (AC) voltage. The power supply circuit includes a rectifier circuit configured to rectify the AC voltage, a first line coupled to the rectifier circuit, a second line on a ground side, a switch coupled between the first line and the second line, and a control circuit configured to control the switch to bring a level of the output voltage to the predetermined level. The power supply circuit is free of an inductor interposed between the first line and the rectifier circuit.

Abstract: A switching control circuit for controlling a power supply circuit that includes an inductor to which an input voltage is applied and through which an inductor current flows, and a transistor configured to control the inductor current. The switching control circuit includes first and second error voltage output circuits that output first and second error voltages, based respectively on a feedback voltage corresponding to the output voltage and a reference voltage, and on an error signal corresponding to a difference between the level of the output voltage and a second level, when the power supply circuit is of a non-isolated type and an isolated type, respectively. The switching control circuit further includes a drive circuit that switches the transistor based on the inductor current, and on the first and second error voltage when the power supply circuit is of the non-isolated type and an isolated type, respectively.

Abstract: A switching control circuit for controlling a power supply circuit that includes an inductor to which an input voltage is applied and through which an inductor current flows, and a transistor configured to control the inductor current. The switching control circuit includes first and second error voltage output circuits that output first and second error voltages, based respectively on a feedback voltage corresponding to the output voltage and a reference voltage, and on an error signal corresponding to a difference between the level of the output voltage and a second level, when the power supply circuit is of a non-isolated type and an isolated type, respectively. The switching control circuit further includes a drive circuit that switches the transistor based on the inductor current, and on the first and second error voltage when the power supply circuit is of the non-isolated type and an isolated type, respectively.

Abstract: A power supply control circuit arranged to prevent a steady power loss from occurring in an input filter connected to an alternating current power source. In order to detect that an AC input has been turned off, diodes are connected to AC lines, thus detecting a full-wave rectified waveform. This detected voltage is compared with a reference voltage by a comparator. An output signal of the comparator is input into the reset terminal of a timer circuit having a time measurement period longer than the power source frequency of an alternating current power source. A switch element of a discharging circuit is turned on by an output signal of the timer circuit.

Abstract: A miniaturized direct-current switch with which power loss is reduced when establishing continuity of a direct-current path is provided. The direct-current switch includes an electronic open/close switch inserted in a direct-current path along which a direct current flows in order to make the direct-current path an open circuit or a closed circuit, a parallel mechanical open/close switch connected in parallel to the electronic open/close switch, and a switch control circuit that controls the opening or closing time difference mutually between the parallel mechanical open/close switch and the electronic open/close switch, wherein the switch control circuit makes the parallel mechanical open/close switch a closed circuit a predetermined time after the electronic open/close switch has been made a closed circuit.

Abstract: A power supply control circuit arranged to prevent a steady power loss from occurring in an input filter connected to an alternating current power source. In order to detect that an AC input has been turned off, diodes are connected to AC lines, thus detecting a full-wave rectified waveform. This detected voltage is compared with a reference voltage by a comparator. An output signal of the comparator is input into the reset terminal of a timer circuit having a time measurement period longer than the power source frequency of an alternating current power source. A switch element of a discharging circuit is turned on by an output signal of the timer circuit.

Abstract: A miniaturized direct-current switch with which power loss is reduced when establishing continuity of a direct-current path is provided. The direct-current switch includes an electronic open/close switch inserted in a direct-current path along which a direct current flows in order to make the direct-current path an open circuit or a closed circuit, a parallel mechanical open/close switch connected in parallel to the electronic open/close switch, and a switch control circuit that controls the opening or closing time difference mutually between the parallel mechanical open/close switch and the electronic open/close switch, wherein the switch control circuit makes the parallel mechanical open/close switch a closed circuit a predetermined time after the electronic open/close switch has been made a closed circuit.

Abstract: A switching power supply device has lower correction circuit losses, and enables adjustments without affecting overcurrent limiting or other characteristics. An integrated circuit IC for power supply control generates a switching signal based on a feedback signal from a feedback circuit and a voltage signal from a current detection input terminal, and outputs the switching signal from an output terminal to a switching element. A voltage controlled oscillator is provided which, when the load is judged to be light based on the magnitude of the feedback signal, lowers the switching frequency. The correction circuit is connected between the output terminal of the integrated circuit and the signal input terminal for current detection, acts only when the switching element is on, and has the function of further lowering the switching frequency set in the integrated circuit.

Abstract: A switching power supply equipment has a function to protect a power supply from abnormalities such as an output short-circuit. An output signal from an error amplification circuit to amplify a difference voltage between an output voltage and a predetermined voltage is input into a feedback terminal of an integrated circuit power supply control circuit, and a power transistor is controlled by a pulse-width control circuit base on the output signal. n addition, a comparator having a reference voltage and a series circuit of a capacitor and a resistor making operation of an overload protection circuit delay are connected to a connecting point of the error amplification circuit and the pulse-width control circuit. The overload protection circuit starts operation by an output of the comparator.

Abstract: A switching power supply device has lower correction circuit losses, and enables adjustments without affecting overcurrent limiting or other characteristics. An integrated circuit IC for power supply control generates a switching signal based on a feedback signal from a feedback circuit and a voltage signal from a current detection input terminal, and outputs the switching signal from an output terminal to a switching element. A voltage controlled oscillator is provided which, when the load is judged to be light based on the magnitude of the feedback signal, lowers the switching frequency. The correction circuit is connected between the output terminal of the integrated circuit and the signal input terminal for current detection, acts only when the switching element is on, and has the function of further lowering the switching frequency set in the integrated circuit.

Abstract: A switching power supply equipment has a function to protect a power supply from abnormalities such as an output short-circuit. An output signal from an error amplification circuit to amplify a difference voltage between an output voltage and a predetermined voltage is input into a feedback terminal of an integrated circuit power supply control circuit, and a power transistor is controlled by a pulse-width control circuit base on the output signal. n addition, a comparator having a reference voltage and a series circuit of a capacitor and a resistor making operation of an overload protection circuit delay are connected to a connecting point of the error amplification circuit and the pulse-width control circuit. The overload protection circuit starts operation by an output of the comparator.

Abstract: A power supply circuit improves the power factor when the load is light, and incorporates a starting circuit for reacting quickly to the changes in the output from the power supply circuit and a short-circuit detecting means for detecting the short-circuit of the feedback signal. The apparatus includes: an error amplifier; a comparator that monitors the output from the error amplifier and generates an offset regulating current ISO; a multiplier; a sensing current comparator that compares the output signal from the multiplier and the AC line current and generates a reset signal; a timer that directly monitors the inputted zero-cross signal; and a comparator for short-circuit detection, that facilitates reducing the exterior parts and components.

Abstract: A power supply circuit improves the power factor when the load is light, and incorporates a starting circuit for reacting quickly to the changes in the output from the power supply circuit and a short-circuit detecting means for detecting the short-circuit of the feedback signal. The apparatus includes: an error amplifier; a comparator that monitors the output from the error amplifier and generates an offset regulating current ISO; a multiplier; a sensing current comparator that compares the output signal from the multiplier and the AC line current and generates a reset signal; a timer that directly monitors the inputted zero-cross signal; and a comparator for short-circuit detection, that facilitates reducing the exterior parts and components.