Evergreen Micro Devices Co., Ltd.

Run Qin Tan

Matthew Man Ho Ku

Li Fang Guo

A controller for reducing the harmonics contents in the AC-to-DC converter that is capable of minimizing THD due to crossover distortion. The controller can approximate the shape of the current running through boost inductor to the sinusoidal waveform of the rectified line input voltage and in the meantime to keep the valley of rectified sinusoidal waveform line voltage close to local ground value. The controller can be used in a transition mode power factor correction device suitable for a wide range of AC line input voltage and output loading application.

Transition mode power factor correction device with built-in automatic total harmonic distortion reduction feature

The present invention relates to clamp protection circuit and a PFC control circuit employing such clamp protection circuit. Said clamp protection circuit comprises a high voltage isolation module used for receiving power from a high voltage power supply; a voltage clamp module used for receiving an output low voltage from the high voltage isolation module and realizing a clamp protection; and a low voltage bias module used for providing bias voltage to the high voltage isolation module and the voltage clamp module. By employing the clamp protection circuit, the precision of the clamp voltage is improved, the design is simplified and the silicon area is reduced. Meanwhile, the transient response is enhanced. Moreover, when the clamp protection circuit is applied in a PFC control circuit, the design of the whole PFC control circuit is simplified and the silicon area is reduced, and the precision and transient response of the clamp voltage of the clamp protection circuit inside the PFC control circuit are improved.

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Shenzhen, China

Run Qin Tan