Path: ...!weretis.net!feeder6.news.weretis.net!usenet.blueworldhosting.com!diablo1.usenet.blueworldhosting.com!feeder.usenetexpress.com!tr1.iad1.usenetexpress.com!69.80.99.22.MISMATCH!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 17 Apr 2024 15:18:53 +0000 From: John Larkin Newsgroups: sci.electronics.design Subject: Re: Predictive failures Date: Wed, 17 Apr 2024 08:17:10 -0700 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: References: X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 61 X-Trace: sv3-7R5aE90AnZL+1ushNoIhcW8TaFj+8uGqb5R1NGICnCncBBDiDabzKWqzUEOJHL7iTEp1x4GDfXlDaW+!6sih9v7t0PaikkKUNyHoMoPdRipGR+7mVwNBj7yJlmAWXrMi1P3gDvlTSqbn+CIyixrwCTkfhz7v!A/oM1A== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3780 On Tue, 16 Apr 2024 20:23:46 -0700, John Larkin wrote: >On Tue, 16 Apr 2024 21:16:45 -0400, "Edward Rawde" > wrote: > >>"John Larkin" wrote in message >>news:p47u1j1tg35ctb3tcta5qevsfnhgnpcrsg@4ax.com... >>> On Tue, 16 Apr 2024 13:39:07 -0400, "Edward Rawde" >>> wrote: >>> >>> >>>>> On 17/04/2024 1:22 am, John Larkin wrote: >>>>>> On Tue, 16 Apr 2024 09:45:34 +0100, Martin Brown >>>>>> <'''newspam'''@nonad.co.uk> wrote: >>>>>>> On 15/04/2024 18:13, Don Y wrote: >>>>> >>> >>>>Yes I've seen that a lot. >>>>The power rails in the production product came up in a different order to >>>>those in the development lab. >>>>This caused all kinds of previously unseen behaviour including an >>>>expensive >>>>flash a/d chip burning up. >>>> >>>>I'd have it in the test spec that any missing power rail does not cause >>>>issues. >>>>And any power rail can be turned on and off any time. >>>>The equipment may not work properly with a missing power rail but it >>>>should >>>>not be damaged. >>> >>> >>> Some FPGAs require supply sequencing, as may as four. >>> >>> LM3880 is a dedicated powerup sequencer, most cool. >>> >>> https://www.dropbox.com/scl/fi/gwrimefrgm729k8enqrir/28S662D_sh_19.pdf?rlkey=qvyip7rjqfy6i9yegqrt57n23&dl=0 >>> >> >>Ok that doesn't surprise me. >>I'd want to be sure that the requirement is always met even when the 12V >>connector is in a position where it isn't sure whether it's connected or >>not. >>Or rapid and repeated connect/disconnect of 12V doesn't cause any issue. >> > >We considered the brownout case. The MAX809 handles that. > >This supply will also tolerate +24v input, in case someone grabs the >wrong wart. Or connects the power backwards. > > Another hazard/failure mode happens when things like opamps use pos and neg supply rails. A positive regulator, for example, can latch up if its output is pulled negative, though ground, at startup. Brownout dippies can trigger that too. Add schottky diodes to ground.