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Validate electronics robustness: Part 2—Find the worst case

11/19/2010 00:52 AM EST
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docdivakar
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re: Validate electronics robustness: Part 2—Find the worst case
docdivakar   11/25/2010 11:47:51 PM
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@Sanjib.Acharya & @hm: the Saber WCA tool is more a design tool that adds a level of confidence in the reliability of the electronic system built using the WCA-tested circuit. It is NOT a tool to predict the MTTF of an electronic system built using the WCA-verified circuit. Whether is space, defense or commercial application, DFM review is a core piece of the development activity and is routinely done these days. I have used FMEA Pro and Weibull++ (Reliasoft) and other similar products to predict MTTF. Nothing beats real product/component level testing to predict MTTF. There are many interactions of various parameters (temperature, material behavior, to mention a few) that take place during testing that circuit simulators simply can not model accurately. Dr. MP Divakar

JurgenFr
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re: Validate electronics robustness: Part 2—Find the worst case
JurgenFr   11/23/2010 4:19:11 PM
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There is another approach not mentioned that is superior to WCA in many cases. WCA is required in some industries of course. A problem with WCA is that designers sometimes "conveniently" leave out variables that should be included but would cause the WCA to fail. To have a successfull WCA outcome typically drives component tolerances to be extremely tight which may be fine for one-of mission critical systems but would raise product cost in high volume manufacturing needlessly. If a MonteCarlo Analysis is run on a system passing WCA and the probability distribution of the output parameter is examined you will find the WCA result to frequently be sigma out on the curve hence an extremely unlikely occurrence. MonteCarlo Analysis allows computing Cpk and setting reasonable tolerances that still achieve a ~0 failure rate. There is an alternative to Monte Carlo Analysis that computes as fast as WCA but gives a more realistic metric of system robustness and reliability. It is based on sensitivity factors and tolerances and computes expected Cpk. I will be publishing a paper on this soon.

Sanjib.A
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re: Validate electronics robustness: Part 2—Find the worst case
Sanjib.A   11/23/2010 1:41:26 PM
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Hi hm, I see what you were saying...thank you. I agree with you. I have also not experienced using a circuit simulation tool for reliability analysis so far. Generally the tools such as FMEA, HAZOP etc. are used for such amalysis. That's why I was interested to know if the tool discussed in this article is capable of generating reliability parameters such as failure rate / MTTF of an electronic system...and also the price as you have also requested.

_hm
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re: Validate electronics robustness: Part 2—Find the worst case
_hm   11/23/2010 4:33:30 AM
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Sanjib, I have worked in Space industry and they do employ this tools. I have also worked for defense but I have observed, more often then not, these tools are not employed by them. As for industrial electronics, they use off-the-self instruments and systems and they never asked for such detail testing as their requirement. Thorsten, will you please give us list price for some of your basic modules?

Sanjib.A
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re: Validate electronics robustness: Part 2—Find the worst case
Sanjib.A   11/22/2010 3:19:58 PM
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Hi, the tools used to determine the reliability of an electronic system is not limited to the space and defense related systems, but they are now an essential part of every electronics system used for safety critical application in Oil & Gas, Boiler, Machine Safety, Automotive, Nuclear etc. sectors. The cost of additional time & effort for reliability analysis, cost of tools etc. translated into the higher product costs for such applications are well justified by the reduced insurance premium the customers have to pay.

t.alex
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re: Validate electronics robustness: Part 2—Find the worst case
t.alex   11/22/2010 2:41:26 AM
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The tool mentioned here is mainly for circuit design and simulation or it can be used for system simulation?

_hm
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CEO
re: Validate electronics robustness: Part 2—Find the worst case
_hm   11/21/2010 4:47:00 AM
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This tools are good for high reliability applications like space and defence. However, it does need lots of resources - time, man power and cost for tools. They are very difficult to justify to management. Also it effect time to market and cost of the final product, though it should be performed ideally. Physical prototype testing as per MIL or other standard gives you very good feedback, probability of confidence of reliabiliy of devices. Engineer may perofrm abovementioned detailed analysis, if he has perticular concern for some aspects. However, doing it for all may be futile excercise in many situation.

Sanjib.A
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CEO
re: Validate electronics robustness: Part 2—Find the worst case
Sanjib.A   11/20/2010 5:56:18 PM
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This looks to be a great Reliability Analysis Tool...thanks for the information. I have a few questions: 1. Is this tool capable to analyze the reliability of analog circuits only? or digital circuits (processor/CPLD/FPGA based circuits)too? 2. Can the tool generate reliability parameters such as "Failure Rate" OR "MTTF" (Mean Time to Failure) for a circuit? 3. Approximately how much does the tool cost?

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