A snubber circuit connected to a rectifying circuit including a reference potential node, an output potential node, and the snubber circuit comprises a snubber capacitor; a snubber diode; and a snubber resistor, wherein a negative electrode of the snubber capacitor is connected to the reference potential node, an anode of the snubber diode is connected to the switch node and a cathode of the snubber diode is connected to a positive electrode of the snubber capacitor, one end of the snubber resistor is connected to the positive electrode of the snubber capacitor, and another end of the snubber resistor is connected to the output potential node, and a reverse recovery time of the snubber diode is longer than a reverse recovery time of the rectifying element.

A snubber circuit connected to a rectifying circuit including a reference potential node, an output potential node, and a first switch node, the snubber circuit comprises a snubber capacitor; a first snubber diode; a snubber coil; and a snubber resistor, wherein a negative electrode of the snubber capacitor is connected to the reference potential node, an anode of the first snubber diode is connected to the first switch node and a cathode of the first snubber diode is connected to a positive electrode of the snubber capacitor, and one end of a series circuit configured by the snubber coil and the snubber resistor is connected to the positive electrode of the snubber capacitor, and another end of the series circuit is connected to the output potential node.

A boost converter includes a first inductor, a first switch element, a second switch element, a tuning circuit, and an output stage circuit. A first parasitic capacitor is built in the first switch element. The first switch element selectively couples the first inductor to a ground voltage according to a first control voltage. A second parasitic capacitor is built in the second switch element. The second switch element selectively couples the first inductor to the output stage circuit according to a second control voltage. The tuning circuit includes a second inductor, a third inductor, and a discharge path. The first parasitic capacitor resonates with the second inductor and is coupled through the discharge path to the ground voltage, or the second parasitic capacitor resonates with the third inductor and is coupled through the discharge path to the ground voltage.

A buffer circuit coupled in parallel to a rectifier circuit in a secondary side of a flyback converter, the buffer circuit including: a capacitive element configured to be charged by an output capacitor when a primary power switch in the flyback converter is turned on; and the capacitive element being configured to be discharged through a secondary winding of a transformer when the primary power switch is turned off, in order to reduce energy stored in a primary leakage inductor in a primary side of the flyback converter, whereby a spike voltage generated in a secondary leakage inductor in the secondary side is reduced, and efficiency of the flyback converter is improved.

Reliability of a semiconductor device is improved. In the semiconductor device SA1, a snubber capacitor pad SNP electrically connected to the capacitor electrode of the snubber capacitor is formed on the surface of the semiconductor chip CHP.

This DC pulse power supply device comprises a voltage clamper including a capacitor that is connected in parallel to a DC reactor in a chopper circuit provided in a pulsing unit in order to suppress increases in the surge voltage resulting from the leakage inductance of the DC reactor. During the start-up of pulsing operation, which is the initial stage of the pulse mode, the frequency of the pulsing operation of the chopper circuit is controlled over the period until the capacitor voltage is charged to a sufficient voltage to reset the magnetic saturation of the DC reactor.

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.

A snubber capacitor includes a first electrode, a second electrode and a capacitor core therebetween. A conductive first extraction element is electrically coupled to the first electrode and covers at least a part of the first electrode and a part of the capacitor core. A conductive second extraction element is electrically coupled to the second electrode and covers at least a part of the second electrode and another part of the capacitor core. The first extraction element is insulated from the second extraction element.

A snubber circuit connected to a rectifying circuit including a reference potential node, an output potential node, and the snubber circuit comprises a snubber capacitor; a snubber diode; and a snubber resistor, wherein a negative electrode of the snubber capacitor is connected to the reference potential node, an anode of the snubber diode is connected to the switch node and a cathode of the snubber diode is connected to a positive electrode of the snubber capacitor, one end of the snubber resistor is connected to the positive electrode of the snubber capacitor, and another end of the snubber resistor is connected to the output potential node, and a reverse recovery time of the snubber diode is longer than a reverse recovery time of the rectifying element.

A controlling method of a converter includes performing a state detecting step and a switch controlling step. The state detecting step is performed to detect an operation state of a secondary side rectifier of the converter from a control winding. The switch controlling step is performed to control an active clamp switch of the converter according to the operation state of the secondary side rectifier. The secondary side rectifier is a diode.