A voltage conversion circuit and a non-isolated power supply system are provided. The voltage conversion circuit includes: a switching power supply chip which includes a power MOS transistor and a driving circuit, where the driving circuit is adapted to drive the power MOS transistor; and a driving circuit power supply unit which includes a boost unit, wherein when an output voltage of the boost unit is less than a working voltage of the driving circuit, an internal power supply of the switching power supply chip provides the working voltage for the driving circuit; and when the output voltage of the boost unit reaches the working voltage of the driving circuit, the output voltage of the boost unit provides the working voltage for the driving circuit.

A charge pump includes a first-stage switch, intermediate-stage switches, and a final-stage switch sequentially connected in series to a power line from an input terminal side. A snubber circuit is connected to the intermediate-stage switch. The snubber circuit includes a capacitor and first and second diodes. The capacitor is connected in series to the first diode and the series circuit of the capacitor and the first diode is connected in parallel to the intermediate-stage switch. The cathode of the second diode is connected to a node between the capacitor and the first diode and the anode of the second diode is connected to output terminal.

A power converter includes a rectifier configured to rectify an AC voltage supplied from an AC power supply, a booster circuit configured to boost the voltage rectified by the rectifier, a smoothing capacitor configured to smooth the voltage output from the booster circuit, a power module configured to convert a DC voltage obtained by smoothing the output voltage by the smoothing capacitor into an AC voltage, and a snubber capacitor configured to absorb a surge voltage superimposed on the DC voltage to be input to the power module. The snubber capacitor is mounted in the power module.

A modulator for a flying-capacitor type multilevel converter receives, at an input, a time-variant reference signal and provides, at an output, a sequence of target levels, to provide switching signals for switching between discrete output levels of the multilevel converter according to the shape of the reference signal. The modulator determines a critical level as an intermediate output level of the multilevel converter which is closest to the level of the reference signal; and outputs only target levels corresponding to output levels different from the critical level.

An active-clamp flyback converter is provided with improved active-clamp switch control that switches on an active-clamp switch at an active-clamp switch on-time that equals a power switch on-time minus a peak charge time for an active-clamp capacitor. The peak charge time is the duration between the switching off of the power switch transistor and when the charging current through the active-clamp capacitor falls to zero. The controller measures this peak charge time following the switching off of the power switch transistor and then applies it to the subsequent switching on of the active-clamp switch so that the active-clamp switch is switched on at the power switch on-time minus the peak charge time.

A power supply device includes a transformer including a primary winding, a secondary winding and an auxiliary winding, first, second and third circuits, and a switch. The first circuit in which a first capacitor and a first rectifier are connected in series is connected to the primary winding in parallel. The switch of which one end is connected to one end of the primary winding. The second circuit in which the auxiliary winding and a second rectifier are connected in serial is connected between a connecting point, to which the first capacitor and the first rectifier are connected, and the other end of the switch. The third circuit including a resistor and a third rectifier is connected to a gate of the switch. In the third circuit, a resistance value in a direction where a current flows into the gate of the switch is smaller than that in a direction where the current flows out of the gate.

An isolated DC-DC converter includes a transformer, a full-bridge switching circuit, a protective circuit, a control unit, an inductor, and an output circuit. The isolated DC-DC converter includes a first voltage detection unit that detects a voltage value between a first conductive path and a second conductive path, and a first current detection unit that detects a current value of the inductor. The control unit determines at least one of a first dead time and a second dead time on the basis of the voltage value detected by the first voltage detection unit and the current value detected by the first current detection unit, using a method that increases the dead time as the voltage value increases and reduces the dead time as the current value increases.

The present disclosure relates to a transient voltage suppression device comprising a single crystal semiconductor substrate doped with a first conductivity type comprising first and second opposing surfaces, a semiconductor region doped with a second conductivity type opposite to the first conductivity type extending into the substrate from the first surface, a first electrically conductive electrode on the first side contacting the semiconductor region and a second electrically conductive electrode on the second side contacting the substrate, a first interface between the substrate and the semiconductor region forming the junction of a TVS diode and a second interface between the first electrically conductive electrode and the semiconductor region or between the substrate and the second electrically conductive electrode forming the junction of a Schottky diode.

An insulated power supply circuit includes a power input circuit including a switching control circuit and a switching element connected to a corresponding winding of a transformer, and power output circuits of two systems each including a regulator connected to a corresponding winding. By the control circuit controlling ON/OFF of the switching element in accordance with an output condition change command signal, which is generated based on a load condition at an output destination of each regulator, a voltage corresponding to an estimated value of a preset excitation level is generated, to thereby change the excitation level of the winding. Each regulator receives an output voltage generated in a corresponding winding in response to the change in excitation level.

A totem-pole PFC circuit is provided. The totem-pole PFC circuit includes an inductor, a first bridge arm and a second bridge arm. The first bridge arm includes a first switch and a second switch connected in series. A first middle node connected between the first and second switches is coupled to a first terminal of an AC power source through the inductor. The second bridge arm connected to the first bridge arm in parallel includes a third switch and a fourth switch connected in series. A second middle node connected between the third and fourth switches is coupled to a second terminal of the AC power source. When a polarity of the AC power source is changed, a change time of a voltage on the second middle node is longer than a preset time not less than 20 μs.