A 30 W Power SupplyWave Resonant Mode30瓦电源 准平方运算方法 波共振模式.PDF

Prepared by: Christophe Basso ON Semiconductor APPLICATION NOTE INTRODUCTION 230 Quasi−Square Wave Resonant converters, often noted QR converters, offer an elegant means to make Flyback supplies Lf look more friendly on the Electro−Magnetic Interference 170 Ip · Ctot (EMI) point of view. By delaying the ON switching event until the drain−source voltage has decayed to a minimum, 110 switching losses are reduced and rising slopes lose their stiffness. Designers get an immediate benefit from this 50 configuration since the MOSFET runs cooler and the EMI input filter becomes easier to implement. Designing QR Switch−Mode Power Supplies (SMPS) requires some −10 attention but is not an area dedicated to experts only. 1.69U 1.73U 1.77U 1.81U 1.85U You will discover through the following lines how new ON Semiconductor solutions can help you to quickly turn Figure 1. A Truly Resonating Vds Signal on a your quasi−resonant project into a working device. Quasi−Resonant Flyback Converter What is Quasi−Resonance? The term quasi−resonance is normally related to the The main problem with this technique lies in the very high association of a real hard−switching converter and a voltage generated at the switch opening.