A dimmer switch system electrically connected between a power source and a load includes a primary housing including a primary switch actuatable by a user, a processor structured to change a state of the dimmer switch based on actuation of either the primary switch or the secondary switch, and a secondary switch isolation circuit. The dimmer switch system also includes a secondary housing including a secondary switch actuatable by the user and being electrically connected to the power source. The secondary switch isolation circuit is electrically connected between the secondary switch and the processor, the secondary switch isolation circuit including a transistor electrically coupled between the power source and the processor and being structured to provide impedance between the power source and the processor. The secondary switch isolation circuit is structured to provide a signal to the processor based on a state of the secondary switch.

A switching power supply includes a first switching element connected between a primary winding of a transformer for the switching power supply and the ground, a shunt regulator serving as an output voltage detection circuit configured to detect an output voltage on a secondary winding side of the transformer, a photocoupler configured to transmit the output voltage to a control circuit, a second switching element configured to receive a stop signal for stopping operation of the switching power supply, and a photocoupler drive circuit configured such that when the second switching element has received the stop signal, power output from a low-frequency transformer power supply or the switching power supply is supplied to the photocoupler, and the stop signal is transmitted to the control circuit via the photocoupler.

A switching power supply includes a first switching element connected between a primary winding of a transformer for the switching power supply and the ground, a shunt regulator serving as an output voltage detection circuit configured to detect an output voltage on a secondary winding side of the transformer, a photocoupler configured to transmit the output voltage to a control circuit, a second switching element configured to receive a stop signal for stopping operation of the switching power supply, and a photocoupler drive circuit configured such that when the second switching element has received the stop signal, power output from a low-frequency transformer power supply or the switching power supply is supplied to the photocoupler, and the stop signal is transmitted to the control circuit via the photocoupler.

A power supply includes a boost converter, a capacitor, a step-down converter and a control unit. The boost converter, when activated, converts an input voltage into a boost voltage. The capacitor has a bulk voltage which is equal to the boost voltage when the boost converter is activated. The step-down converter converts the boost voltage into a step-down voltage for output. While the boost converter is deactivated, the control unit samples the input voltage and the bulk voltage, calculates an estimated value, and determines a calibration parameter. While the boost converter is activated, the control unit calculates a calibration value for enabling the boost converter to convert the input voltage with reference to the calibration value.

A power supply includes a boost converter, a capacitor, a step-down converter and a control unit. The boost converter, when activated, converts an input voltage into a boost voltage. The capacitor has a bulk voltage which is equal to the boost voltage when the boost converter is activated. The step-down converter converts the boost voltage into a step-down voltage for output. While the boost converter is deactivated, the control unit samples the input voltage and the bulk voltage, calculates an estimated value, and determines a calibration parameter. While the boost converter is activated, the control unit calculates a calibration value for enabling the boost converter to convert the input voltage with reference to the calibration value.

A power conversion device, which includes an insulation type full bridge converter and can switch a power transmission direction at a high speed, is provided. A DC/DC converter (10) constitutes a power conversion device, which operates as a first type converter that converts a voltage within a first range applied to a first input/output terminal pair into a voltage within a second range and outputs the voltage from a second input/output terminal pair or a second type converter that converts a voltage within the second range applied to the second input/output terminal pair into a voltage within the first range and outputs the voltage from the first input/output terminal pair, as a device that performs predetermined state transition of the DC/DC converter (10) after waiting for a load current value of a secondary side of a transformer (TR) to be a value within a predetermined current value range.

A power conversion device, which includes an insulation type full bridge converter and can switch a power transmission direction at a high speed, is provided. A DC/DC converter (10) constitutes a power conversion device, which operates as a first type converter that converts a voltage within a first range applied to a first input/output terminal pair into a voltage within a second range and outputs the voltage from a second input/output terminal pair or a second type converter that converts a voltage within the second range applied to the second input/output terminal pair into a voltage within the first range and outputs the voltage from the first input/output terminal pair, as a device that performs predetermined state transition of the DC/DC converter (10) after waiting for a load current value of a secondary side of a transformer (TR) to be a value within a predetermined current value range.

A power supply circuit includes: an anti-electromagnetic interference circuit configured to receive input alternating current power and to output filtered alternating current power; a rectifier circuit configured to rectify the filtered alternating current power; a current correction circuit configured to perform passive power factor correction on the rectified alternating current power; a single-ended flyback converter circuit coupled to the output of the current correction circuit; and a dimming control circuit coupled between the output of the single-ended flyback converter circuit and a light load, wherein the current correction circuit is configured to control a waveform of the rectified alternating current power to follow a current output to the light load in order to provide passive power factor correction.

A power supply circuit includes: an anti-electromagnetic interference circuit configured to receive input alternating current power and to output filtered alternating current power; a rectifier circuit configured to rectify the filtered alternating current power; a current correction circuit configured to perform passive power factor correction on the rectified alternating current power; a single-ended flyback converter circuit coupled to the output of the current correction circuit; and a dimming control circuit coupled between the output of the single-ended flyback converter circuit and a light load, wherein the current correction circuit is configured to control a waveform of the rectified alternating current power to follow a current output to the light load in order to provide passive power factor correction.

A power supply circuit includes: an anti-electromagnetic interference circuit configured to receive input alternating current power and to output filtered alternating current power; a rectifier circuit configured to rectify the filtered alternating current power; a current correction circuit configured to perform passive power factor correction on the rectified alternating current power; a single-ended flyback converter circuit coupled to the output of the current correction circuit; and a dimming control circuit coupled between the output of the single-ended flyback converter circuit and a light load, wherein the current correction circuit is configured to control a waveform of the rectified alternating current power to follow a current output to the light load in order to provide passive power factor correction.