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Single-end Flyback with RCD snubber (DC input version)


Flyback topologies are the most common and widely used topologies in auxiliary power supply design. Fly-back converter could be single phase as well as three phase types.  Fly- back is most commonly used due to its simplicity in design and control, less components, low cost solution, and built-in galvanic isolation.
Single end fly-back is typically used for the power supplies < 250W.


An overview of relevant components, power class and topologies is shown in below table.



Key Products

Product Category Product family Product Number Remark
Controller QR BM1Q021FJ Linear type, fsw<120kHz
QR BM1P061FJ /BM1P101FJ Gate clamper, fsw=65kHz /100kHz
QR BM1P10CFJ Gate clamper, Low power mode, X-cap. Discharge, fsw= 100kHz
Discrete MOSFET 600 / 650V SJ MOS R60xxKN / R65xxKN Good compromise between performance and ease of use.
Diode (D1)
Secondary Rectifier
Schottky Barrier Diodes RBQ /RBxx8 series Ultra low IR SBD is suitable for rectification purpose, RBxx8 series has wide range of voltage choise
Diode (Ds)
800V Si FRD RFS series Lower Vf than RSV series, but ultra fast switching capability


C-010. DC-DC Flyback Converter Vin=800V, Vo=25V, Io=10A

Related Topologies

Interleaved Boost PFC

Totem-Pole Bridgeless PFC (Diode Rectification)

Totem-Pole Bridgeless PFC (Synchronous FETs)