Joulwatt Technology Co., Ltd.

Joulwatt Technology (hangzhou) Co., Ltd.

Xianghua Jiang

Pitleong Wong

Xunwei Zhou

Xiangyong Xu

Junming Zhang

Disclosed is a high-efficiency flyback converter and a control method thereof. The flyback converter comprises: a transformer; a first switch transistor and a second switch transistor; a resonant capacitor; a control circuit, for controlling the second switch transistor to be turned on for a first time before the first switch transistor is turned on during a switching cycle, controlling the second switch transistor to maintain turn-off state during a first time stage, to control energy transmission between primary and secondary sides to include two time stages during a switching cycle, the first time stage lasts for a set time period during a freewheeling process. The present disclosure allows the main switch transistor to realize zero-voltage turn-on, thus reducing conduction loss of the primary and the secondary sides, reducing ripples of an output voltage and a current of the secondary side, and being beneficial to improving operating efficiency.

Flyback converter with high efficiency and control method thereof

A control method and control circuit of a switched-mode power supply, and the switched-mode power supply are provided. An operating mode of the switched-mode power supply is controlled in a first mode and a second mode according to an output feedback signal of the switched-mode power supply. One operating period of the first mode includes a switch period of a boundary conduction mode (BCM), and one operating period of the second mode includes N switch periods of BCMs and a switch period of a discontinuous conduction mode (DCM). The auxiliary switch transistor is turned on once to discharge a parasitic capacitor of the main switch transistor when the switched-mode power supply enters the next operating period from one operating period of the current second mode before the next operating period starts or the switched-mode power supply enters the first mode from the current second mode before the first mode starts.

Control method and control circuit of switched-mode power supply, and switched-mode power supply

A clamping switch abnormality detection method, a clamping switch abnormality detection circuit and a switch circuit are provided, wherein an active clamping flyback circuit includes a clamping switch, a main switch and a transformer. When a clamping switch control signal is active, a switching node voltage or a voltage on an auxiliary winding or an magnetizing inductor current is detected, and when the switching node voltage or the voltage on the auxiliary winding or the magnetizing inductor current oscillates, or the switching node voltage is less than a first voltage threshold or the voltage on the auxiliary winding is less than a second voltage threshold, the clamping switch is abnormal or a clamping switch driving circuit is abnormal. The switching node is a common node of the transformer and the main switch, and the transformer includes a primary winding, a secondary winding and the auxiliary winding.

Clamping switch abnormality detection method, clamping switch abnormality detection circuit and switch circuit

An active clamping flyback circuit and a control method are disclosed, comprising a flyback circuit, a clamping circuit and a clamping control circuit. The active clamping flyback circuit comprises a transformer, a main transistor, and a freewheeling diode or a synchronous rectifier, an output feedback circuit is coupling to an auxiliary winding of the transformer and outputs a feedback voltage through a divided voltage The clamping circuit comprises a first capacitor and a first transistor coupling in series, In a discontinuous conduction mode, the clamping control circuit starts timing from a turn-off time of the first transistor, and ends timing until the feedback voltage is reduced to zero voltage, to obtain a first time, The clamping control circuit adjusts a turn-off moment of next switching cycle of the first transistor so that the first time of the next switching cycle is close to a first threshold.

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Hangzhou, China

Xianghua Jiang