Bcd Semiconductor Manufacturing Limited

Shanghai Sim-Bcd Semiconductor Manufacturing Co., Ltd.

Bcd Semiconductor Manufacturing Co., Ltd.

Other

Diodes Inc.

Yajiang Zhu

Chao Chen

Qiang Zong

Shuzhuang Lv

Xiaoru Gao

ShaoHua Fang

Ruixia Fei

Meiling Zhang

Hu Wang

Jia Xie

Zeqiang Chen

Yongbo Zhang

Na Liu

Xuegang Ren

Siyuan Xu

Jianhua Duan

Shihai Zhu

BaoZhen Chen

Tao Peng

Chao Gao

Zheng Ying

Pingan Zhao

Huizhen Zhu

Zhimin Hu

Xianfeng Liu

Jinhua Duan

Chao Deng

Wenhui Dong

Yanping Wang

Yawei Tang

A switch mode power supply (SMPS) system includes a rectifying circuit for coupling to an AC input voltage and a transformer having a primary winding for coupling to the rectifying circuit and a secondary winding coupled to the primary winding. The system also has a power switch coupled to the primary winding and a control circuit coupled to the power switch. The control circuit is configured to control current flow in the primary winding such that an envelope waveform formed by peak points of current pulses is in phase with the magnitude of the AC input voltage. Moreover, the SMPS system is configured to provide a constant average output current.

High power-factor control circuit and method for switched mode power supply

A control circuit for a switch mode power supply (SMPS) includes a power switch for coupling to a primary winding of the power supply and a startup resistor coupled to an external input voltage and to a control terminal of the power switch. The control circuit also includes a controller. During startup, the controller is configured to cause the power switch to amplify a startup current from an external input voltage through the startup resistor and provide a startup power to the controller. During normal operation, the controller is configured to provide a power switch control signal to turn on and off the power switch for controlling a current flow in the primary winding and regulating an output of the power supply. The controller is configured to provide a current signal for driving an NPN power switch and to provide a voltage signal for driving an NMOS power switch.

Fast startup control circuit for switch mode power supply

A switch mode power supply (SMPS) has a primary-side controller configured to control a power switch for turning on and turning off a current flow in the primary winding. A secondary-side controller is coupled to the secondary winding for providing constant voltage (CV) and constant current (CC) control of the SMPS. The secondary-side controller is configured to receive an output selection signal and, based on the output selection signal, select a voltage reference signal from a plurality of voltage reference signals and select a current reference signal from a plurality of current reference signals. The secondary-side controller is configured to monitor an output voltage and an output current of the SMPS, and is configured to provide a turn-on signal to the primary-side controller for turning on the power switch upon determining that the output voltage is below the selected voltage reference signal and the output current is below the selected current reference signal.

Switching mode power supply with selectable constant-voltage constant-current control

A control circuit is provided for a buck converter that includes at least an inductor coupled to an output of the buck converter. The control circuit includes a power switch configured for coupling to a line voltage and configured for charging the inductor, an input line voltage sampling circuit, and a constant-voltage (CV) and constant-current (CC) control module coupled to the power switch. During a charging period of the inductor, the CV and CC control module is configured to control the power switch to provide a constant output current by maintaining a constant peak inductor current, even when the input line voltage changes. During a discharging period of the inductor, the CV and CC control module is configured to monitor the sensed output voltage to control the power switch to provide a constant output voltage.

Constant-voltage and constant-current buck converter and control circuit

A switching mode power supply (SMPS) includes a transformer having a primary winding, a secondary winding for providing an output voltage, and an auxiliary winding. The SMPS also includes a power switch coupled to the primary winding. A first control circuit is coupled to the secondary winding, and is configured to provide a first electrical signal to the secondary winding when the output voltage of the SMPS is less than a reference voltage during a discontinuous time, whereupon a second electrical signal is induced in the auxiliary winding. A second control circuit is coupled to the auxiliary winding and the power switch. The second control circuit is configured to regulate the output of the SMPS by controlling the power switch in response to a feedback voltage signal from the auxiliary winding, and is further configured to turn on the power switch in response to the second electrical signal.

Control circuits and methods for switching mode power supplies

A power supply controller is provided for providing a drive current to a control terminal of a power transistor in three time intervals. The controller includes control circuits configured to control the drive current in multiple stages. During a first time interval, first drive current includes a current spike for turning on the power transistor in response to a start of the control signal pulse. During a second time interval, a second drive current includes a ramping current substantially proportional to a magnitude of a current through the power transistor. During a third time interval, current flow to the power transistor is at least partially turned off before an end of the control signal pulse.

Power transistor driving circuits and methods for switching mode power supplies

An SMPS received a rectified periodic input line voltage and is configure to provide a regulated output. A power switch has a constant turn-on time in a given cycle of the rectified periodic input line voltage. A maximum value of the envelope of peak currents through the power switch is determined and is compared with a reference value, and the power switch turn-on time in the next cycle is adjusted accordingly. The output of the power supply is regulated to a target output value, and the current is in phase with the periodic input line voltage, resulting in a high power factor. No sampling of the line voltage is needed to maintain the high power factor. A controller chip can have as few as five pins. Alternatively, a seven-pin controller chip can have two external resistors for selecting operations in either Boundary Conduction Mode (BCM) or Discontinuous Conduction Mode (DCM).

High power-factor control circuit and power supply

A synchronous rectification circuit for a power supply includes a power switch for coupling to a secondary winding of a transformer of the power supply and an output capacitor of the power supply. The power switch includes a four-terminal MOSFET having a source, a drain, a gate, and a body. A body diode is formed by a junction between the body and the drain or by a junction between the body and the source. The body diode is coupled in parallel to the source and drain of the power transistor. A control circuit is configured to provide a control signal for controlling an on/off state of the power switch in response to a voltage condition of two terminals of the power switch. When the body diode makes a transition from reverse bias to forward bias, the control circuit causes the MOSFET to turn on, and when the forward bias voltage drops below a reference voltage, the control circuit causes the MOSFET to turn off. When the body diode makes a transition from forward bias to reverse bias, the control circuit causes the MOSFET to turn off.

System and method for synchronous rectifier

A switch mode power supply (SMPS) system includes a rectifying circuit for coupling to an AC input voltage and a transformer having a primary winding for coupling to the rectifying circuit and a secondary winding coupled to the primary winding. The system also has a power switch coupled to the primary winding and a control circuit coupled to the power switch. The control circuit is configured to control current flow in the primary winding such that an envelop waveform formed by peak points of current pulses are in phase with the magnitude of the AC input voltage. Moreover, the SMPS system is configured to provide a constant average output current.

A switched mode power supply (SMPS) includes a transformer with a primary winding, a secondary winding, an auxiliary winding, and a power switch coupled to the primary winding. During one switching cycle, the auxiliary winding provides a feedback signal which includes a first voltage pulse that is induced after the power switch is turned on and a second voltage pulse that is induced after the power switch is turned off. A control circuit includes a circuit for generating a sampling signal for sampling the second voltage pulse in a switching cycle at a time that is determined based on the first voltage pulse in the same switching cycle. A sample-and-hold circuit is configured for sampling and storing the second voltage pulse in response to the sampling signal. A switching signal generating circuit is configured to generate a switching signal for controlling the power switch based on an output of the sample-and-hold circuit.

Control circuit for primary side control of switching power supply

A switching mode power supply (SMPS) includes a rectifying device configured for converting a periodically varying input AC (alternating current) voltage into a DC (direct current) voltage, and a transformer including a primary winding, a secondary winding, and an auxiliary winding. The primary winding is coupled to the rectifying device. An input capacitor is coupled to the rectifying device and the primary winding of the transformer. A first power switch is coupled to the input capacitor. A control circuit is coupled to the first power switch and is configured to control the first power switch based on a phase or amplitude of the input AC voltage. By controlling the charging and discharging of the input capacitor, power is provided to the primary winding during a longer portion of the AC input voltage cycle, allowing the rectifier device to have a larger conduction angle to increase a power factor (PF).

Circuits and methods for increasing power factor of switch mode power supply

A pulse frequency modulation (PFM) controller for controlling a switching mode power supply. The controller includes an output terminal for providing a control signal to turn on and off a current in the power supply to regulate an output of the power supply. A first input terminal receives a feedback signal related to the output of the power supply, the feedback signal exhibiting a ringing waveform when the current in the power supply is turned off. The controller also includes a control circuit configured to provide the control signal in response to the feedback signal. The control signal is adapted to turn on the current in the power supply when the feedback signal is substantially at a valley of the ringing waveform of the feedback signal. In an embodiment, such a PFM controller can reduce turn-on transition loss in a power supply and provides frequency dithering to reduce electromagnetic interference.

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Shanghai, China

Yajiang Zhu