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 <jjSNIPlarkin@highNONOlandtechnology.com>
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: <uhpv1jd4b0cd20haudbsb3dneut5dap4ka@4ax.com>
References: <uvjn74$d54b$1@dont-email.me> <uvldrf$rpnh$1@dont-email.me> <ak5t1j5bmuiito091au53lshmqgpv3mvtr@4ax.com> <uvmao8$124q1$1@dont-email.me> <uvmd3u$8n3$1@nnrp.usenet.blueworldhosting.com> <p47u1j1tg35ctb3tcta5qevsfnhgnpcrsg@4ax.com> <uvn7tv$1big$1@nnrp.usenet.blueworldhosting.com> <mufu1jhjt8m0pjphcmj519k371c8bc0h0t@4ax.com>
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
<jjSNIPlarkin@highNONOlandtechnology.com> wrote:

>On Tue, 16 Apr 2024 21:16:45 -0400, "Edward Rawde"
><invalid@invalid.invalid> wrote:
>
>>"John Larkin" <jjSNIPlarkin@highNONOlandtechnology.com> wrote in message 
>>news:p47u1j1tg35ctb3tcta5qevsfnhgnpcrsg@4ax.com...
>>> On Tue, 16 Apr 2024 13:39:07 -0400, "Edward Rawde"
>>> <invalid@invalid.invalid> 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.