> But I have zero experience in transformer based step up circuits. Anyhow,=
 I
> don't want to wound my own transformer, as this circuit may (with some
> hope) later become part of a production device. It needs to have an enabl=
e
> pin and it will be used to charge capacitors (probably around 15uF @ 400V=
).
>=20
> Any hint or guide? I wouldn't mind if as a controller I'd have to use a P=
IC, as I
> already need one in my circuit anyway and it has plenty of CPU time avail=
able
> also for this task, and anyway I'd like to learn something about transfor=
mer
> step up (or should I call it inverter?) technology anyway, algorithms, co=
ntrol
> strategies, etc.. so an independent IC is not really necessary.
>=20
> Where do I start? Should I drive a couple of MOSFETs to feed the primary
> side of the transformer with a low voltage high current square wave?
> Does it have to be AC? Can't I use a pulse transformer and feed DC pulses=
?

Check out any of the SMPS chip suppliers application notes. IIRC National S=
emiconductor, ST or Linear Technology had app notes using SMPS chips to do =
step up conversion, and that would point you at standard transformers from =
Wurth, Coilcraft, and possibly some Japanese manufacturers. If you can't fi=
nd chip suppliers app notes, just browse the catalogues of the companies me=
ntioned.

I don't think you will get 50W out of a standard pulse transformer. I suspe=
ct from the PIC point of view you are going to need to look at a chip that =
has a complementary PWM drive to drive the transformer, so one of the dsPic=
 chips designed for power supplies would be a good starting point, although=
 there are 16F1xxx and 16F1xxxx chips which I believe have similar PWM thes=
e days.



--=20
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