A discharge circuit includes: a first transistor connected to power storage; an operational amplifier for controlling an output current of the first transistor; and the current mirror circuit connected to the operational amplifier. The current mirror circuit includes a second transistor connected to a non-inverting input terminal of the operational amplifier, and a third transistor connected to the power storage.

A power transfer device includes a first power supply node, a second power supply node, and an oscillator circuit configured to convert an input DC signal across the first power supply node and the second power supply node into an AC signal on a differential pair of nodes comprising a first node and a second node in response to a control signal. The oscillator circuit includes a regulated power supply node and an active shunt regulator circuit configured to clamp a peak voltage level across the regulated power supply node and the second power supply node to a clamped voltage level. The clamped voltage level is linearly related to a first voltage level on the first power supply node.

A power transfer device includes a first power supply node, a second power supply node, and an oscillator circuit configured to convert an input DC signal across the first power supply node and the second power supply node into an AC signal on a differential pair of nodes comprising a first node and a second node in response to a control signal. The oscillator circuit includes a regulated power supply node and an active shunt regulator circuit configured to clamp a peak voltage level across the regulated power supply node and the second power supply node to a clamped voltage level. The clamped voltage level is linearly related to a first voltage level on the first power supply node.

A power transfer device includes an oscillator circuit of a DC/AC power converter responsive to an input DC signal and an oscillator enable signal to generate an AC signal. The oscillator circuit includes a first node, a second node, and a circuit coupled between the first node and the second node. The circuit includes a cross-coupled pair of devices. The oscillator circuit further includes a variable capacitor coupled between the first node and the second node. A capacitance of the variable capacitor is based on a digital control signal. A first frequency of a pseudo-differential signal on the first node and the second node is based on the capacitance. The power transfer device further includes a control circuit configured to periodically update the digital control signal. A second frequency of periodic updates to the digital control signal is different from the first frequency.

A power transfer device includes an oscillator circuit having a first node, a second node, and a control terminal. The oscillator circuit includes a cascode circuit comprising transistors having a first conductivity type and a first breakdown voltage. The cascode circuit is coupled to the control terminal, the first node, and the second node. The oscillator circuit includes a latch circuit coupled between the cascode circuit and a first power supply node. The latch circuit includes cross-coupled transistors having the first conductivity type and a second breakdown voltage. The first breakdown voltage is greater than the second breakdown voltage. The oscillator circuit may be configured to develop a pseudo-differential signal on the first node and the second node. The pseudo-differential signal may have a peak voltage of at least three times a voltage level of an input DC signal on a second power supply node.

A resonant converter includes: an input power supply, a bleeder circuit, a multi-level switching network, a resonant unit, and a transformer. The input power supply is connected to the bleeder circuit, the multi-level switching network is connected to the bleeder circuit, a clamping middle point of the multi-level switching network is connected to a middle point of the bleeder circuit; one end of the resonant unit is connected to the output terminal of the multi-level switching network, and the other end of the resonant unit is connected to one end of a primary side of the transformer; and the multi-level switching network instructs the output terminal of the multi-level switching network to output a square wave voltage with different amplitudes, to serve as an input voltage of the resonant unit, where the input voltage is used to adjust a gain of the resonant converter.

A switched-mode power supply according to an embodiment comprises a switching circuit, a smoothing circuit, a differential-signal output circuit, a signal output circuit, a pulse-drive signal output circuit, and a signal generation circuit. The differential-signal output circuit is configured to output a differential signal based on a potential difference between the output voltage and a reference potential. The signal output circuit is configured to generate a signal synchronous. The pulse-drive signal output circuit is configured to adjust a time ratio of outputting the voltage on a basis of a time point when the differential signal and the signal have a same value. The signal generation circuit is configured to generate at least either the differential signal or the signal to cause an interval from a base time in one cycle of the clock signal to the time point to decrease as the input voltage increases.

A DC-DC converter and method are provided for converting a low voltage DC input to a higher voltage DC output. The DC-DC converter has an oscillator with a first relatively voltage sensitive and relatively low power transistor and a second relatively voltage insensitive and relatively high power transistor, the oscillator producing an AC signal from the low voltage DC input. The inclusion of the voltage sensitive transistor allows the oscillator to turn on at a relatively low voltage. The inclusion of the higher power transistor allows the oscillator to operate at a higher power once it turns on. The DC-DC converter can be used for converting energy harvested from low voltage sources.

Various improvements are provided to resonant DC/DC and AC/DC converter circuit. The improvements are of particular interest for LLC circuits. Some examples relate to self-oscillating circuit and others relate to converter circuits with frequency control, for example for power factor correction, driven by an oscillator.

Various improvements are provided to resonant DC/DC and AC/DC converter circuit. The improvements are of particular interest for LLC circuits. Some examples relate to self-oscillating circuit and others relate to converter circuits with frequency control, for example for power factor correction, driven by an oscillator.