On Fri, Oct 12, 2007 at 09:46:16AM -0400, John Luciani wrote: > There may be a TL431 application circuit that could be work. Check out > the TL431 datasheet from TI.
Well, I think you've fixed my problem, but it doesn't involve the TL431. But the datasheet inspired me -- I see them using it to control a 7805 three-terminal regulator, which is an interesting idea. (Figure 20 in TI's version of the datasheet at http://www.ti.com/lit/gpn/tl431). The TL432 effectively raises the ground reference of the 7805 to Vout-5V. This would work in my application, as the 7805 would only see Vin-Vout+5V instead of the full 42V, and so it would be operating within its limits. But this basic circuit layout looks suspiciously to me like a basic three-terminal adjustable regulator, using GND in place of the ADJ terminal and the TL431 to provide the reference for that terminal. So why not use a standard-issue three-terminal adjustable regulator circuit? Those things don't care what Vin is, only Vin-Vout. Duh! Thanks for the help, even if you didn't realize what answer you were really giving. ;) -- Randall _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
