Design method of quasiresonant flyback converter based on L6565

CAO Xuewu， QIN Huibin
（School of Electronics & Information， Hangzhou Dianzi University ，Hangzhou 310018， China）

Abstract：In order to improve the power density of switching power supply， reduce the size and the electormagnetic interference(EMI)， lower the power switching device conduction losses，  a quasiresonant flyback converter based on L6565 was introduced，the power MOSFET’s output capacitance and the primary inductance of the transformer were used to produce resonance. Through appropriate control, the zerovoltage switch turnon was realized. With the traditional hardswitching flyback converter than it can effectively reduce the switching loss and improve the converter efficiency.
Key words：flyback converter；quasiresonant； zerovoltage switch (ZVS)