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Re: analog failures

From Joerg <news@analogconsultants.com>
Newsgroups sci.electronics.design
Subject Re: analog failures
Date 2017-02-17 15:37 -0800
Message-ID <egpfp7Fel2lU1@mid.individual.net> (permalink)
References (7 earlier) <o87mdm$qru$2@dont-email.me> <egpackFdjfvU2@mid.individual.net> <o87sjs$h3a$2@dont-email.me> <egpc9uFe0r5U1@mid.individual.net> <o87v36$pph$1@dont-email.me>

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On 2017-02-17 14:58, rickman wrote:
> On 2/17/2017 5:38 PM, Joerg wrote:
>> On 2017-02-17 14:16, rickman wrote:
>>> On 2/17/2017 5:05 PM, Joerg wrote:
>>>> On 2017-02-17 12:30, rickman wrote:
>>>>> On 2/15/2017 11:30 AM, John Larkin wrote:
>>>>>> On Wed, 15 Feb 2017 07:53:18 -0800, Joerg
>>>>>> <news@analogconsultants.com>
>>>>>> wrote:
>>>>>>
>>>>>>> On 2017-02-14 19:55, Reinhardt Behm wrote:
>>>>>>>> AT Wednesday 15 February 2017 11:00, bill.sloman@ieee.org wrote:
>>>>>>>>
>>>>>>>>> On Wednesday, February 15, 2017 at 1:52:23 PM UTC+11, Reinhardt
>>>>>>>>> Behm
>>>>>>>>> wrote:
>>>>>>>>>> AT Wednesday 15 February 2017 07:05, Lasse Langwadt Christensen
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> Den tirsdag den 14. februar 2017 kl. 23.47.11 UTC+1 skrev John
>>>>>>>>>>> Larkin:
>>>>>>>>>>>> http://semiengineering.com/devices-threatened-by-analog-content/
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>
>>>>>>> IME most analog failures are caused by ESD and that is often
>>>>>>> squarely in
>>>>>>> the court of the board level designer.
>>>>>>>
>>>>>>> Upsets without subsequent chip damage are also considered a fault
>>>>>>> where
>>>>>>> the function is mission-critical. That is very often due to EMI.
>>>>>>>
>>>>>>>
>>>>>>>>>>>> My experience is that we find a lot of bugs and documentation
>>>>>>>>>>>> problems
>>>>>>>>>>>> with the digital parts of mixed-signal chips.
>>>>>>>>>>>
>>>>>>>>>>> It does seem like when analog designers get to design the
>>>>>>>>>>> digital
>>>>>>>>>>> parts
>>>>>>>>>>> of a chip it often ends up with a hairball of hazards and weird
>>>>>>>>>>> quirks
>>>>>>>>>>
>>>>>>>>>> That was always my experience with part from NatSemi. Pure analog
>>>>>>>>>> was
>>>>>>>>>> good, pure digital was good, mixed mostly was a mess.
>>>>>>>>>
>>>>>>>>> Mixed signal design is difficult, and doing it on a chip, where
>>>>>>>>> it is
>>>>>>>>> harder to keep the noisy digital bits away from the sensitive
>>>>>>>>> analog bits,
>>>>>>>>> wouldn't have made it any easier.
>>>>>>>>>
>>>>>>>>> Sadly, mixed signal design can do a lot more than pure analog or
>>>>>>>>> pure
>>>>>>>>> digital, so if you have got something complicated to do, that
>>>>>>>>> tends
>>>>>>>>> to be
>>>>>>>>> what you end up doing.
>>>>>>>>
>>>>>>>> It was never the problem of digital noise coupling into the analog
>>>>>>>> portions
>>>>>>>> but the digital totally mixed up, like the LM75 going into a state
>>>>>>>> where
>>>>>>>> only a power cycle helps to get it working again. This can be
>>>>>>>> caused by
>>>>>>>> noise on the I2C signals.
>>>>>>>
>>>>>>>
>>>>>>> I2C is a bus I try not to use if it can be avoided because of
>>>>>>> various
>>>>>>> hang-ups. SPI is much more robust IME and, therefore, that is what I
>>>>>>> prefer.
>>>>>>
>>>>>> I prefer SPI too, and it's faster, but lots of people design terrible
>>>>>> SPI interfaces, bad logic design and bad clock/data circuits. Every
>>>>>> SPI should have schmitt inputs and safe timing margins. Maybe cooking
>>>>>> a digital design into an analog process causes compromises, but I
>>>>>> suspect it's just sloppy engineering.
>>>>>
>>>>> Not trying to be snarky, but most digital engineers work to eliminate
>>>>> noise and to have proper clocks without noise on the transition edge.
>>>>> Schmitt is only needed on the clock inputs, but even there proper
>>>>> design
>>>>> at the board level eliminates the need.
>>>>>
>>>>
>>>> Schmitt is needed everywhere a signal connect to the outside world. A
>>>> lot of uC design engineers do not understand this.
>>>
>>> Define "outside world".  Do you mean off board?
>>>
>>
>> Yes, or via a noisy area on the board. Also if slow on-board sensors are
>> involved.
>
> That's why I said...
>
> "most digital engineers work to eliminate
> noise and to have proper clocks without noise on the transition edge. "
>

... and then overlook that there can be external influences into boards 
and system. Such as EMI, magnetic fields or even weird stuff like that 
inexplicable double-pulse whenever somebody uses the freight elevator. 
But who am I to complain, this stuff brought me plenty of assignments.

-- 
Regards, Joerg

http://www.analogconsultants.com/

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Thread

analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-14 14:47 -0800
  Re: analog failures Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-14 15:05 -0800
    Re: analog failures Reinhardt Behm <rbehm@hushmail.com> - 2017-02-15 10:52 +0800
      Re: analog failures bill.sloman@ieee.org - 2017-02-14 19:00 -0800
        Re: analog failures Reinhardt Behm <rbehm@hushmail.com> - 2017-02-15 11:55 +0800
          Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-15 07:53 -0800
            Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-15 08:30 -0800
              Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-15 10:19 -0800
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-15 10:53 -0800
                Re: analog failures Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-15 10:58 -0800
                Re: analog failures "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-15 21:25 -0600
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-15 20:18 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-17 15:44 -0500
              Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-17 15:30 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 14:05 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-17 17:16 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 14:38 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-17 17:58 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 15:37 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-17 18:51 -0500
                Re: analog failures krw@notreal.com - 2017-02-17 20:27 -0500
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-17 17:56 -0800
                Re: analog failures "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-17 21:03 -0600
                Re: analog failures krw@notreal.com - 2017-02-17 22:36 -0500
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-19 00:45 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-19 08:32 -0800
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-21 12:31 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-23 14:57 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-23 12:02 -0800
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-17 17:27 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-17 20:39 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-18 07:41 -0800
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-18 08:04 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-18 08:16 -0800
            Re: analog failures Reinhardt Behm <rbehm@hushmail.com> - 2017-02-16 06:49 +0800
              Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-16 07:14 -0800
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-16 07:24 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-16 07:41 -0800
                Re: analog failures Reinhardt Behm <rbehm@hushmail.com> - 2017-02-17 13:22 +0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 06:58 -0800
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-17 12:26 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 14:03 -0800
                Re: analog failures "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-17 21:05 -0600
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-18 08:07 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-18 08:20 -0800
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-18 09:20 -0800
                Re: analog failures rickman <gnuarm@gmail.com> - 2017-02-19 00:48 -0500
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-21 12:39 -0800
                Re: analog failures "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-21 22:54 -0600
                Re: analog failures krw@notreal.com - 2017-02-17 20:33 -0500
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-18 07:37 -0800
                Re: analog failures dagmargoodboat@yahoo.com - 2017-02-22 15:45 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-23 10:43 -0800
                Re: analog failures krw@notreal.com - 2017-02-23 20:42 -0500
                Re: analog failures "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-24 03:31 -0600
                Re: analog failures grahamholloway@graham65.plus.com - 2017-02-24 06:39 -0800
                Re: analog failures Don Kuenz <g@crcomp.net> - 2017-02-24 14:58 +0000
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-25 12:48 -0800
                Re: analog failures pcdhobbs@gmail.com - 2017-02-26 04:39 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-26 07:52 -0800
                Re: analog failures dagmargoodboat@yahoo.com - 2017-02-24 09:02 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-25 12:44 -0800
                Re: analog failures dagmargoodboat@yahoo.com - 2017-02-26 08:29 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-26 09:46 -0800
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-26 10:11 -0800
                Re: analog failures krw@notreal.com - 2017-02-26 17:55 -0500
                Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-26 15:09 -0800
                Re: analog failures krw@notreal.com - 2017-02-26 19:30 -0500
                Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-27 10:37 -0800
                Re: analog failures Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-24 09:14 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-25 12:46 -0800
                Re: analog failures Klaus Kragelund <klauskvik@hotmail.com> - 2017-02-26 17:44 -0800
                Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-27 07:51 -0800
                Re: analog failures Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-02-23 21:36 +0200
                Re: analog failures dagmargoodboat@yahoo.com - 2017-02-24 08:38 -0800
                Re: analog failures krw@notreal.com - 2017-02-24 20:20 -0500
                Re: analog failures kevin93 <kevin@whitedigs.com> - 2017-02-24 17:36 -0800
      Re: analog failures Ralph Barone <ralph@invalid.com> - 2017-02-15 03:25 +0000
    Re: analog failures John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-14 19:20 -0800
  Re: analog failures Tim Wescott <seemywebsite@myfooter.really> - 2017-02-14 17:46 -0600
    Re: analog failures Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-14 17:50 -0700
      Re: analog failures Tim Wescott <tim@seemywebsite.com> - 2017-02-14 23:49 -0600
        Re: analog failures Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-15 07:03 -0700
        Re: analog failures John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-15 10:18 -0800
          Re: analog failures Tim Wescott <seemywebsite@myfooter.really> - 2017-02-15 15:06 -0600
  Re: analog failures legg <legg@nospam.magma.ca> - 2017-02-16 23:06 -0500
    Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 07:00 -0800
      Re: analog failures legg <legg@nospam.magma.ca> - 2017-02-17 13:22 -0500
        Re: analog failures Joerg <news@analogconsultants.com> - 2017-02-17 11:06 -0800

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