Re: Any known issues with TPS71xxx regulators?

Hello Jim,

Jim Thompson wrote:

On Fri, 20 Oct 2006 23:42:56 GMT, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:


Hello Mark,


I am sure TI wouldn't endorse this. The ESR needs be low and placing a
10ohm resistor in series would carry the potential that the whole thing
bursts into oscillation.

The input capacitor could be increased a bit but it's on the HV side so
it would cost some space. And right now it is all pretty much what the
data *** recommend. Let's see what TI comes back with tomorrow.


I've just seen some changes to regulator datasheets where there is a caution
about having too low an ESR capacitor. Surprised the hell out of me: not
something I would have looked for, but now I know. May be worth checking
out (Issue is loop stability and would not expect it to be distructive to
the part but...)


The TPS77550 data*** doesn't list a minimum but something on it has been revised in Sep-2006. And we see the problems with recent chips...

Who knows but I'll parse the old and new versions side by side. There is something nice about having two PCs next to each other in the office :-)

Now I am going to have to figure out which tools they still let you take on board. Calling the airline won't help because they won't have the foggiest idea what I am talking about when I say FET probe, and I don't want to give up $2k worth of gear at security.


Crikey! If they're so spooky I think I'd be inclined to use a
discrete PNP, so I could compensate the loop properly.


Here we were hard pressed for space. But it seems that many times where I use a chip it doesn't perform as well as ye olde discrete solution :-(

--
Regards, Joerg

http://www.analogconsultants.com
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