• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 18 subscribers
  • Views 471 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CD74ACT540: How to convert reliability data

Sean Lee26
Prodigy 40 points
Part Number: CD74ACT540

Hi Everyone.

I have a question about the reliability data which are provided from the TI as the attached image below.

On the table, the confidence level is 60% and I want to convert to 90% or 95%.

Can anybody tell me how can I convert confidence level to get the corresponding MTBF or FIT values.

Thanks

Sean

  • 0
    TI__Guru* 96591 points

    Hi Sean,

    There's a calculator at this link that you can use to estimate 90% confidence level DPPM.  The equation used is located at the bottom of the page.

    At 90%, the DPPM is estimated to be 5233 for the CD74ACT540E.

  • 0 in reply to Emrys Maier
    Prodigy 40 points

    Hi. Emrys

    Thank you for your reply...

    But still don't know how I can convert MTBF and FIT value using converted DPPM value...

    Can you describe it for me if you know??

    Thanks again..

    Sean

  • 0 in reply to Sean Lee26
    TI__Guru* 96591 points
    FIT := Failure In Time
    MTBF := Mean Time Between Failure
    DPPM := Defective Parts Per Million

    26.5 FIT indicates that 26.5 failures will occur over 10^9 operating hours (~100000 years)

    And MTBF of 3.77*10^7 hr tells us that failures are likely to have a spacing of ~4300 years.

    The conversion between these two is:

    10^9 / FIT = MTBF

    Remember that the values are measured in 'hours' and you have to convert to years:

    years ~= hours / (24 * 365)


    For DPPM, this is really a measurement of ELFR (Early Life Failure Rate), and isn't exactly the same thing as the above mentioned values... I haven't been able to find a direct conversion, but I'll ask around and see if I can find something for you.
  • 0 in reply to Emrys Maier
    TI__Guru* 96591 points
    Hey Sean,
    I just wanted to let you know that I haven't given up looking for this. I'm currently waiting to hear back from some of my contacts in the reliability/quality team.
  • 0 in reply to Emrys Maier
    TI__Guru* 96591 points
    Hey Sean,
    It looks like there's no direct conversion - it's possible to make a bunch of assumptions and kind of get an estimation from one to the other, but one type of test is for early life failure (ie defective parts) while the other tests for failure over time of otherwise good parts.