Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!purdue!ames!oliveb!apple!xanadu!michael
From: michael@xanadu.COM (Michael McClary)
Newsgroups: sci.electronics
Subject: Re: want help with power supply
Message-ID: <fqRXA#=michael@xanadu.COM>
Date: 5 Aug 89 13:57:51 GMT
References: <113785@sun.eng.sun.com> <10040006@hprmokg.hp.com>
Reply-To: michael@xanadu.UUCP (Michael McClary)
Organization: Xanadu Operating Company, Palo Alto, CA
Lines: 6

In article <10040006@hprmokg.hp.com> barry@hprmokg.HP.COM (Barry Fowler) writes:
>pf is probably Power Fail, a signal issued when a comparator detects that
>the power output is about to be interrupted in ?-milliseconds.

In an Intel supply I've used, the power failure signal was an open-collector.
Add pullups and such as appropriate for your logic family.