I am going to try using a QX5252 to drive 300ma led. The specs imply a 30uH inductor in the 'boost' circuit would do the trick, which I would wind on a small ferrite ring I have, the kind used to suppress rfi by running ribbon cables through it.
But those rings are not 'meant' for hi Q inductors. Are they maybe specially made to be lossy for rfi suppression, and hence not a good choice for a switch mode power application?
I tried to tag this with 'Q' or quality factor, but it wasn't there.