Roman Black scribbled:
>
> 18uH seems very low for 100kHz?? Does the chip datasheet
> specify it should be 18uH?? I would try doubling your
> windings (or even more) to bump it up to 70uH or so,
> and give that a go. :o)

Not specifically the datasheet, but their online and
standalone design tool.  The datasheet has similar
designs that call for a 1:1 transformer with a 22uh
primary.


> Yeah ok, not very "scientific" but then you did ask for
> tips with the transformer design.

True.  Fine, I'll bite.


> Re blowing up the chip,
> are you using a variable load?

No, just a fixed 150-ohm resistor across the output.
This should give me 80mA for now.


> Maybe also try putting a
> 3w 20v zener across your DC input and/or chip, if you
> have a winding reversed (hint hint) it might make lots
> of volts on flyback and fry your chip. :o)

Hmmm.... maybe you could be right.


> -Roman
>

Cheers,
-Neil.

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