Topswitch系列芯片是Power Integration公司生产的开关电源专用集成电路。它将脉宽调制电路(PWM)与高压MOSFET开关管及驱动电路等集成在一起。使用该芯片设计的小功率开关电源。可大大减少外同电路，降低成本，提高可靠性。本文介绍了Topswitch系列芯片的工作原理及用该芯片制作的30W反激式开关电源，并就电路设计中的关键问题做了详解。

Topswitch series integrated circuits are produced especially for power supply by power integration company, which integrate the pulse width controller(PWM) and a high voltage MOSFET together. Designing low power switching power supply with such integrated circuits can decrease parts count, decrease cost and increase reliability. The functional block diagram and reality application circuit are introduced and the key points on design is given.

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