Dave King wrote:
>
> >fiddle tonight with a 40v to 12v design as asked

> Roman buddy pal best friend .. Just going to ask
> if you could do the same thing. ;-]  What would it take
> to run that voltage range and up to say about 3 amps?
>
> This is a bit of serendipity. I found out I can't get any Max727
> for  a few months if at all, or I need to play with a LM2576
> and see how it behaves.

Hi Dave (buddy?) :o)
So you want 24v to 40v in, 12v @ 3A out?

Getting close to 40v input means the buck diode needs
to be rated for 60v, which is starting to push the
common type schottkys. I can get TO220 60v 16A diodes
for about $1.10 USD, provided you take adequate
measures for automotive spikes etc that type would do.

It will only be about 1.5A input so maybe a cheap
n-channel FET could be adapted, or even go with a
low-tech (cheap) bipolar like the BD204 with low sat
spec (and maybe a driver transistor) would work.

I'd like to give it a go in the simplest 2-tran
config I can manage, will be a bit of fun. What sort
of requirements do you have for;
* total size
* inductor type
* cost sensitivity
* quantity
* input filtering
* will it be compared with a specific chip?
:o)
-Roman

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