Fuji Electric Co., Ltd.

Ryuunosuke Araumi

Ryuji Yamada

Takato Sugawara

A switching control circuit for a power supply circuit that includes an inductor configured to receive a rectified voltage corresponding to an alternating current (AC) voltage, and a transistor configured to control a current flowing through the inductor, the power supply circuit generating an output voltage from the AC voltage, the switching control circuit being configured to switch the transistor. The switching control circuit comprises: a signal output circuit configured to output a signal to turn on the transistor, after lapse of a first time period since the inductor current reaches a first predetermined value after the transistor is turned off, the first time period corresponding to a conduction period during which a parasitic diode of the transistor conducts; and a driver circuit configured to turn on the transistor based on the signal, and turn off the transistor, based on a feedback voltage corresponding to the output voltage.

Switching control circuit and power supply circuit

An integrated circuit for a power supply circuit, including: a first command value output circuit outputting a first command value to turn on a transistor of the power supply circuit for a first time period; an on signal output circuit outputting an on signal to turn on the transistor; a delay circuit delaying the on signal by a predetermined time period; a correction circuit correcting the first command value, to output a second command value to turn on the transistor for a second time period; and a driver circuit turning on and off the transistor based respectively on the delayed on-signal and the second command value. The correction circuit corrects the first command value based on the predetermined time period and a ratio between the second time period and another time period from when the transistor is turned off to when an inductor current of the power supply circuit reaches a predetermined value.

Integrated circuit and power supply circuit

A switching control circuit for a power supply circuit, including: a first command value output circuit outputting a first command value; a correction circuit correcting the first command value, to output a second command value; a first timer circuit measuring a first time period starting from a first timing at which a transistor of the power supply circuit is turned on; and a driving signal output circuit outputting a driving signal to turn on the transistor in response to an inductor current of the power supply circuit reaching a predetermined value and the first time period having elapsed since the first timing, and outputting the driving signal to turn off the transistor based on the second command value. The correction circuit causes an on time period of the transistor to increase, when the first time period has elapsed since the first timing, after the inductor current reaches the predetermined value.

A current detection circuit configured to detect a resonant current of a power supply circuit. The power supply circuit includes a resonant circuit that has an inductor and a first capacitor having a first end and a second end. The current detection circuit includes a second capacitor having a first end and a second end, and a non-linear circuit provided between the second end of the second capacitor and the second end of the first capacitor. The first end of the second capacitor is coupled to the first end of the first capacitor.

Current detection circuit including non-linear circuit and power supply circuit containing the same

A switching control circuit controls switching of a switching device, which controls a resonance current of a resonant converter, with a frequency corresponding to an output voltage of the resonant converter. The switching control circuit includes a detection circuit configured to detect a difference between a first timing at which the switching device is turned on and a second timing at which a polarity of the resonance current reverses, and a signal output circuit configured to output a driving signal with a preset minimum frequency, responsive to the difference becoming so small as to satisfy a predetermined condition.

Switching control circuit and resonant converter

A switching control circuit for a power supply circuit that generates an output voltage from an AC voltage. The power supply circuit includes a rectifier circuit rectifying the AC voltage, an inductor receiving the rectified AC voltage, and a transistor controlling an inductor current flowing through the inductor. The switching control circuit controls switching of the transistor, based on the inductor current and the output voltage. The switching control circuit includes a target value output circuit that outputs a target value of a peak value of the inductor current for shaping a waveform of the peak value so as to be similar to a waveform of the rectified voltage, and a drive signal output circuit that outputs a drive signal to turn on the transistor upon the inductor current falling below a predetermined value and turn off the transistor upon the peak value of the inductor current reaching the target value.

Switching control circuit and power factor correction circuit

A switching control circuit for controlling an LLC converter that includes a first switching device, a first free-wheeling diode connected in parallel with the first switching device, a second switching device connected in series with the first switching device and the first free-wheeling diode, and a second free-wheeling diode connected in parallel with the second switching device. The switching control circuit controls switching of the first and second switching devices. The switching control circuit includes a determination circuit determining whether an operation mode of the LLC converter is a first mode or a second mode based on the resonant current of the LLC converter, and a drive signal output circuit outputting first and second drive signals for respectively switching the first and second switching devices based on the determined operation mode, to thereby prevent a shoot-through current from flowing through the first switching device or the second switching device.

Switching control circuit and LLC converter

A switching control circuit that controls switching of a switching device, the switching control circuit includes a frequency modulation circuit that generates an oscillator signal, and modulates a frequency of an oscillator signal with a predetermined frequency and a modulation index of two or more, and a drive circuit that drives the switching device in response to a signal corresponding to the modulated oscillator signal, the predetermined frequency being higher than a frequency indicative of a value that is a quarter of a half width of a bandpass filter used for measuring noise generated when the switching device is driven.

An integrated circuit that drives a switching device provided between a first line on a ground side and a second line on a power supply side, when a power supply voltage is applied between a first input terminal connected with a first capacitor and a second input terminal, the first capacitor having one end grounded and another end connected to the first input terminal, the integrated circuit includes: a first terminal connected to a circuit element, the circuit element having one end grounded and another end connected to the first terminal; and a drive circuit that changes a voltage at the first terminal to one logic level when a drive signal of the switching device changes to the one logic level, and changes the voltage at the first terminal to another logic level when the drive signal changes to the other logic level.

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Kawasaki, Japan

Ryuunosuke Araumi