On 11/2/06, Dave McGuire <[EMAIL PROTECTED]> wrote:
On Nov 2, 2006, at 8:15 PM, Bob Paddock wrote: >> I'll look into it. The thing about op amps is that they're cheap and >> tiny. > > Which frequently gets people into trouble when they try to use > Op-Amps as Comparators: ... > TI: > Op Amps and Comparators - Don't Confuse Them > > Operational amplifiers (op amps) and comparators look similar; they > even have very similar schematic symbols. > This leads a lot of designers to think they are interchangeable. > There is a strong temptation to use a spare section > of a multiple op amp package as a comparator to save money. This > application note will explain why designers should not do this. > > http://encon.fke.utm.my/nikd/latest/sloa067.pdf > Download .pdf (sloa067.pdf, 150 Kbytes)"Not to butt in, but...wow, that is a VERY informative article...Thanks for sending that URL! -Dave
I think the article is overstating things a little bit. Sure, op-amps make lousy, slow comparators. But commercially successful op-amps aren't going to burn up if you let the output go to a rail! Some high-spec opamps may have limitations, such as high current in the input stage if you exceed a certain differential voltage, but these limitations should be called out in the datasheet. And expensive, exotic amps aren't the ones being pressed into comparator duty. Regards, Mark [EMAIL PROTECTED] -- You think that it is a secret, but it never has been one. - fortune cookie _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
