Hi,

We are doing FSGM0565 replacement with TOP255GN...however, i am forced to use transformer with np/ns = 84/19 and so its in CCM at low mains (its 90-265vac).

Its 24v, 0.8a.

The feedback loop calc from AN57 is giving nonsense figures.

Also, AN57 says Q should be taken as 0.15....but this is way off....Q is given on page 8 of TN-203 by microsemi...it would be more like 58.

please shed light on AN57?

I cannot use TOP255GN if cannot garantee good feedback loop.

They wont use Inno or TOP-JX because they like the TOP255GN package.

Also, what is this about resonance needing to be above 500Hz.?..that would mean a limit on output capacitance, which is surely nonsense?