Batchellor, Gary wrote:
>
> Sorry I left out some of the info.  What total current range? The 12v will
> be occasional loading (motors), so it will be 10amps or
> nothing. The 5v will be from a low of .5a to a max of 3a. Down to zero amps?
> On the 12v side but the 5v no.
> How much regulation needed? Regulation can be a bit sloppy especially on the
> 12v side. The 5v I would like to keep within about .3 +/- Input voltage? 24v
> to 36v dc
> Efficiency needs? This isn't a big concern right now.


I suggest driving the motors via PWM directly from
the 24v or 36v side. You can use the same FETs
with no 12v PSU needed, less parts, better efficiency,
and much higher motor performance available.
Stepper motors and good DC servos are almost always
driven this way.

The 5v up to 3A is do-able with the 2-tran one
inductor circuit, with the right transistor
choices. BUT this project sounds expensive in total,
the obvious choice would be a dedicated 5v smps
regulator chip, and the chip specs would have
charts suggesting a good inductor size and type
saving you some research.

Is it a robot?
-Roman

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