On 24/03/2008, William Chops Westfield <westfw@mac.com> wrote:
>
> In the attached circuit I've overlaid a standard buck-mode converter
> (SW2, CR2, L1), and a boost mode converter (SW1, CR1, L1) that shares
> the same inductor.
>
> Is there some reason that this doesn't work as a boost/buck variable
> voltage regulator? (for boost, you leave SW2 ON continuously, for
> buck you leave SW1 off all the time.)  I don't think I've ever seen
> this sort of configuration.  (for that matter, I haven't seen many
> switch-mode variable power supplies at all...)  I can forsee "issues"
> trying to run this with a traditional analog feedback path, but if
> I'm using a microcontroller as the regulating element anyway?
>
> Thanks
> Bill W
>
>
Bill,
Looks like it should work. In the buck mode you have an additional
diode drop from the "standard" configuration. I'm not sure how the
optimum value for L would work out.

Why not use the traditional buck-boost circuit?


Richard P
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