There aren't many places where a mediocre Q-factor is useful.
Certain powdered irons (namely #26 and #52) are too lossy to use in most, say, flyback converter applications. But they're not so lossy that they just go "thud", so you still need a damper or snubber to absorb the ring-down EMI.
Actually, it's pretty close, I've done it before. Sooo lossy...
Anyway, that's the same as hooking a big fat resistor across the winding. It's not a high-frequency-only thing, like an R+C damper. It's just... lossy.
An application where efficiency doesn't matter, like my recent current limiting circuit breaker device, benefits from losses to the extent that:
- It doesn't cut into accuracy of the current limit (a solid-iron core would be dominantly resistive, and not really do any filtering anymore);
- Any loss in the core is loss I don't have to handle elsewhere (in transistors, resistors, TVSs, etc.). More components handling more power = more cost. Anywhere I can economize is a win.
This is a good application for something like a #26 powdered iron, instead of a gapped ferrite core.
If you're using a pot core, it sounds like you're already well above the point where anything like this can apply.
So... maybe, sometimes -- but no?
Also, on the subject of both #26 toroids and 150V buck converters, you may be interested to see this?
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First tried a #26 here, cooked itself. Then a Kool-Mu, also cooked itself (but slower). Finally changed to gapped ferrite, just because I have a shitton of 'em. Now it runs quite cool, because, well, of course it does...
Tim