On Sun, 23 Mar 2008 23:12:13 -0700, "William Chops Westfield"
<westfw@mac.com> said:
> 
> 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?


Hi Bill,

For years I've used the MAX710 from our "favorite" semiconductor
manufacturer. Not only does it use that topology but it also adds the
user-selectable option of a low-dropout linear regulator on the output
side so you don't get a glitch when it swaps modes.

Cheerful regards,

Bob


-- 
http://www.fastmail.fm - The way an email service should be

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist