A switching power supply apparatus includes a PFM control circuit that outputs a clock signal Set such that a switching frequency of a switching element varies in accordance with a load state. The clock signal Set determines a turn-on timing of the switching element. A reference value of a current flowing through the switching element determines a turn-off timing of the switching element. A modulation signal is applied to the turn-off timing of the switching element to modulate one of a peak value of a drain current flowing through the switching element and an on-time of the switching element. Input control is performed separately on the clock signal Set and the modulation signal. Accordingly, even when the clock signal Set and the modulation signal contribute to each other to offset each other, modulation effects are not cancelled.

Provided is a high-frequency power supply device capable of causing an appropriate current to flow through a transformer. A self-oscillation high-frequency power supply device is provided with a DC power supply, an LC resonant circuit, a switching circuit, and a transformer. The LC resonant circuit includes an induction coil for plasma generation and a capacitor. The switching circuit includes a semiconductor element, the switching circuit being configured to subject DC power supplied from the DC power supply to switching processing to supply high-frequency power to the LC resonant circuit. The transformer includes a primary coil included in the LC resonant circuit and a secondary coil connected to the semiconductor element to turn on/off a semiconductor element. The transformer has a coaxial structure in which the primary coil and the secondary coil are coaxially provided. The LC resonant circuit includes a resistor connected in parallel to the primary coil.

A switching power supply comprising: a feedback element; a voltage detection element which is connected to the feedback element at secondary side of the switching power supply and changes current which flows to the feedback element based on output voltage of the switching power supply; a control circuit which is connected to the feedback element at primary side of the switching power supply and controls the switching element; and a current detection resistor which is connected to the switching element, wherein the controller circuit controls burst mode or normal mode based on voltage which is occurred in a first terminal which is connected between the current detection resistor and the switching element and a value based on voltage which is occurred in a second terminal which is connected to the feedback element, sets the switching element ON until the voltage which is occurred in the first terminal reaches to the value based on the voltage which is occurred in the second terminal, and sets the switching element OFF when the voltage which is occurred in the first terminal reaches to the value based on the voltage which is occurred in the second terminal, further comprising: a change circuit which changes inclination of the voltage which is occurred in the first terminal.

A switching power supply apparatus includes a PFM control circuit that outputs a clock signal Set such that a switching frequency of a switching element varies in accordance with a load state. The clock signal Set determines a turn-on timing of the switching element. A reference value of a current flowing through the switching element determines a turn-off timing of the switching element. A modulation signal is applied to the turn-off timing of the switching element to modulate one of a peak value of a drain current flowing through the switching element and an on-time of the switching element. Input control is performed separately on the clock signal Set and the modulation signal. Accordingly, even when the clock signal Set and the modulation signal contribute to each other to offset each other, modulation effects are not cancelled.

A power converter connected between a direct current power supply and a load, the power converter including a switching unit energizing the load based on inputted control signal, a voltage detector detecting a voltage of the direct current power supply, and a protection operation portion detecting a steep elevation of the voltage and performing protection operation to stop a switching operation by the switching unit, wherein the protection operation portion includes an addition circuit adding a predetermined voltage to the voltage detected by the voltage detector and a delay time generator connected to an output of the addition circuit, and wherein the protection operation is performed when a difference between the voltage detected by the voltage detector and an output voltage of the delay time generator reaches a certain value.

A synchronous rectifier controller integrated circuit. The synchronous rectifier controller integrated circuit comprises a continuous current mode (CCM) detection circuit configured to detect CCM operation based on sensing a voltage at a pre-defined point in a rectification cycle; a multiplexer having a first reference voltage signal input, a second reference voltage signal input, an output, and a selector input coupled to the CCM detection circuit; and a gate voltage driver circuit coupled to the output of the multiplexer.

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.

A switch-mode power supply includes a control element in a primary circuit for controlling a transformer for transmitting electric energy from the primary circuit to a secondary circuit, a first regulating element in the secondary circuit for regulating an electric output variable of the secondary circuit, and a second regulating element in the primary circuit for regulating an electric controlled variable of the control element as a function of a temperature of the primary circuit, the second regulating element being thermally coupled to an element of the primary circuit whose temperature is to be ascertained.

To prevent an overvoltage from being applied to a load in a power reception circuit of a power supply system. A power supply system is provided which includes a power supply device equipped with a power supply coil, and a power reception device equipped with a power reception coil. When a resonance circuit is in a resonance state, a peak voltage value of a voltage generated in the power reception coil is set higher than a prescribed voltage value. When the resonance circuit is in a non-resonance state, the peak voltage value of the voltage generated in the power reception coil is set lower than the prescribed voltage value.

A controller including a voltage synthesizer for a switching regulator includes a synthesizer input to be coupled to an input of the regulator. First and second replica switching transistors are connected at a first node. A resistor couples between the first node and a second node, and a capacitor couples between the second node and ground. A transconductance stage compares a voltage sampled onto the capacitor to the output voltage of the regulator and generates an output signal in response to the comparison. A first switch couples between first and second inputs of the transconductance stage. The first switch is turned on during each cycle of operation of the voltage synthesizer to reset the capacitor voltage to the output voltage of the regulator.