Shanghai Sim-Bcd Semiconductor Manufacturing Co., Ltd.

Bcd Semiconductor Manufacturing Limited

Zhimin Hu

Yajiang Zhu

Xuegang Ren

Na Liu

Siyuan Xu

Qun Li

Jianhua Duan

Zeqiang Chen

Lei Cheng

Junelei Li

Chao Deng

A bleeder circuit is provided in a switched mode power supply (SMPS) that provides a compensation current when the loop current drops below the holding current of the TRIAC to alleviate light flickering problem. Further, automatic power factor correction is also provided in embodiments of the invention, which enables the output current to be in phase with the input voltage. The power factor correction not only improves the efficiency of the power supply, it can also reduce the compensation current and the duration in which compensation current flows, thereby reducing the power loss in the bleeder circuit.

Power supply for LED lamp with TRIAC dimmer

A switch mode power supply (SMPS) includes a buck converter circuit that includes a first inductor coupled to an output terminal and a switch device coupled the first inductor. A controller is configured for regulating the output current based at least in part on controlling a peak current in the first inductor according to a ratio between an instantaneous voltage to an average voltage at the negative output terminal. The controller is configured to cause the SMPS to operate in a boundary conduction mode (BCM). The controller is configured to maintain a constant average output current that is substantially independent of the input voltage and the output voltage, and also provide a high power factor.

Method and circuit for constant current buck converter

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

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Shanghai, China

Zhimin Hu