Joulwatt Technology Co., Ltd.

Chengdu Monolithic Power Systems Co., Ltd.

Xiangyong Xu

Xianghua Jiang

Junming Zhang

Pitleong Wong

Yike Li

Yang Yang

Mengyi Huang

Zhiyong Su

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 frequency regulating circuit for a switching circuit, a frequency regulating method, and the switching circuit are provided. The frequency regulating circuit includes a charging current generating module configured to receive a first signal characterizing an output power and a second signal characterizing an input voltage to generate a charging current and a signal generating module configured to output a third signal according to the charging current. The third signal is used to adjust the maximum operating frequency of the switching circuit so that the maximum operating frequency decreases with the increase of the input voltage. Therefore, the frequency regulating circuit increases the maximum operating frequency of the switching circuit under the condition of low voltage input, which decreases the maximum operating frequency of the switching circuit under the condition of high voltage input to reduce the switching loss of the switching circuit with wide input voltage and improve efficiency.

Frequency regulating circuit, frequency regulating method and switching circuit

Disclosed is a flyback converter and a control method thereof. The flyback converter comprises: a transformer; a power switch; a driver; a synchronous rectifier; and a feedback control module, wherein the feedback control module is configured to output a primary-side turn-on signal when a new switching cycle is started; in each switching cycle, the feedback control module is configured to turn off a primary-side power switch according to a voltage across the synchronous rectifier and an output voltage of the flyback converter. The flyback converter only needs a single isolation device to achieve lossless equivalent peak current control and driving interlocking of primary side and the secondary side, and the synchronous rectifier can effectively prevent driving shoot-through of the primary side and the secondary side in terms of control without reducing a drive voltage, which further improves system efficiency and reliability.

Flyback converter and control method thereof

The present disclosure relates to a flyback converter and a power supply system. The flyback converter comprises: a transformer; a first switching transistor and a second switching transistor; a first inductor and a first capacitor; and a control circuit. The control circuit includes an under voltage protection module configured to determine an under voltage protection threshold proportional to an output voltage of the flyback converter and to trigger an under voltage protection action of the flyback converter in a case that an input voltage of the flyback converter is less than the under voltage protection threshold. By setting an adaptive under voltage protection threshold, a system-restart phenomenon of the flyback converter after an input power failure or a shutdown may be avoided, and a PFC circuit may be turned off to optimize the standby power consumption and the low load efficiency in fast charging applications using an flyback topology.

Flyback converter and power supply system with dynamic under voltage protection

A current limiting circuit of a switching circuit, and a switching circuit are provided. The switching circuit uses a gallium nitride (GaN) power transistor as a main power transistor. The current limiting circuit includes a first terminal connected with a drain of the GaN power transistor, and a second terminal connected with a controller of the switching circuit. The current limiting circuit is configured to limit a current flowing out of a power supply terminal of the controller. The current limiting circuit suppresses a negative current flowing through the controller.

Current limiting circuit of switching circuit and switching circuit

Disclosed is an asymmetric half-bridge flyback converter and a control method, including: in an initial switching cycle of the asymmetric half-bridge flyback converter, obtaining a pre-turnoff time of the second switch transistor, and controlling the second switch transistor to be turned off after a delay which lasts for a first time and starts at the pre-turnoff time of the second switch transistor; in a non-initial switching cycle of the asymmetric half-bridge flyback converter, obtaining a judgment result by judging whether the first switch transistor is operated with zero-voltage switching in a current switching cycle, and adjusting a length of the first time based on the judgment result. The present disclosure can realize zero-voltage switching of the asymmetric half-bridge flyback converter, and at the same time, satisfy a requirement for achieving more ideal dead-time setting under a wider range of input voltage and a wider range of output voltage.

Asymmetric half-bridge flyback converter and control method thereof

A switching-type regulation driver includes a transformer, a controller, a synchronous rectifier and a drive control module. The drive control module is connected to the synchronous rectifier and the non-dotted terminal of the secondary winding respectively, and is used to detect a target parameter of a voltage across both power ends of the synchronous rectifier when the synchronous rectifier disconnects the conductive path between the non-dotted terminal of the secondary winding and the reference ground. When it is detected that the target parameter of the voltage across both power ends of the synchronous rectifier meets a preset condition, the controller controls a switching action of the first transistor so that the primary winding transmits power to the secondary winding. According to the present disclosure, the pre-stage chip may be matched with to realize a function of dynamic acceleration, and the dependence on the output pin may be reduced.

Switching-type regulation driver and regulation driving method thereof

A controller having an on-time controller, an off-time controller, a switch control signal generator, and a jittering signal generator, wherein the jittering signal generator couples jitter into the on-time or the off-time of a primary switch of the power supply. Therefore the EMI performance may be improved.

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Hangzhou, China

Xiangyong Xu