I'm designing a DC-DC Flyback or SEPIC converter, not decided yet.

The converter is used to source some power LED's. The output voltage up to 60V and 1A with an input of 12-24V. The switching frequency should be between 100kHz and 1MHz, because of the switching losses, we are considering a rather low frequency.

So I just had a glance what type of coupled inductors may be avaiable on the market.

I looked first for an inductor with ~40uH series inductance at a current raiting above 5A and an even higher satturation current.

But I could just find some rather strange products, looking like ment for a rather specific application.

Are there other more common terms than "coupled inductor" to find such products? Also manufacturer names would be helpful.

I know a transformer may met my conditions, but are transformers not by general ment to transform energy rather than store it?

  • \$\begingroup\$ In general, flyback transformers are custom wound. \$\endgroup\$
    – winny
    Commented Dec 28, 2020 at 9:15
  • 1
    \$\begingroup\$ Is there a reason you are not considering a standard boost converter? Also, can you be clear about what switching frequency you are considering? \$\endgroup\$
    – Andy aka
    Commented Dec 28, 2020 at 10:24

1 Answer 1


A coupled inductor is also known as a flyback transformer. It is intended to operate in a different mode from what is traditionally called a power transformer. You are correct that a traditional power transformer does not store appreciable energy. A fly-back transformer, on the other hand, stores energy for part of its "cycle", and then releases that energy, through the "secondary", during another part. It is essentially an inductor with two magnetically coupled coils.


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