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quality issues and date code

Mark Tillmann
Prodigy 110 points
Part Number: DAC7725

I have a few questions regarding part# DAC7725N

What is the difference between parts that have the TI logo and parts that have the "Burr-Brown" logo.

I was surprised to still see that the parts still have "Burr-Brown" on them since TI bought them in 2000.

Besides the part#, there are some other characters below it.

Not sure if it is a DIE code or a date code or both.

Here is an example:

15S5FD8

Can you tell be the date of manufacture?

I am also seeing some electrical anomolies with the parts but I will wait for an answer on the date code question first.

Thanks for you  rime,

Mark

  • 0
    TI__Mastermind 46290 points

    Mark,

    Not necessarily all of the top-side markings were updated after the TI acquisition of Burr-Brown. As far as I can tell reviewing historical and current builds of the DAC7725, they all still bear the Burr-Brown logo.

    That said, the specific top-side marking numbers you have provided do not match any of the builds I can find. Can you provide a photo of the unit?

    Assuming it were a correct number it would suggest that this was a unit built in June, 2011. However given the age of this part it is also possible that it was built in June, 2001.

    From where did you acquire this unit?

    What sort of anomalies are you observing?

  • 0 in reply to Kevin Duke
    Prodigy 110 points

    Kevin - here is a picture of the device.  I currently have 7 of them that I've pulled off boards.

    These parts are from our in-house Arrow store.

     

    I am an in-circuit test engineer using an Agilent 3070 to test an assembly which utilizes the DAC7725.

    Some anomalies that I have seen are a low input impedance on a control line or one of the 12 digital bit inputs (b0-b11)

    Ideally, the input impedance would be >1Meg.  I have seen some input impedances as low as 500ohms.

    I also recently started walking a one across the digital input lines to verify that the output steps up by the weight of the specific bit.

    The reference voltage is 5.00V so the LSB weight is 1.22mV.

    When stepping from 0 to 1, a good part will read 1.22 +/- 0.1LSB on the two channels that I am able to monitor (CHA and CHC)

    A bad part may read 250uV on one channel and 1.22mV on the other Channel.

    Sometimes both channels read very low.

    Below is a picture of one of the parts.

    Any information regarding the age of the parts would be very useful.

    i.e. if these parts are 7+ years old, that is a problem.

  • 0 in reply to Mark Tillmann
    TI__Mastermind 46290 points
    Hi Mark,

    I can say with certainty that these parts either came from 2011 or 2001. I can't say for sure which one because I cannot find the top-side codes in any of our manufacturing records. I'm not sure how well that database transferred from old parts from near 2000, so it's possible that is why I cannot find it.

    I will enlist the help of someone a bit more versed in these systems from our program management side of things and see if they can find these specific parts.

    Can you speak to the approximate percentage of observed bad units from the overall population? Was this an existing design in production that has recently started to show these problems? If the rate is common enough, we could provide some sample units from the TI eStore which would come from a newer manufacturing lot to try to isolate the topic of old parts etc. versus in-circuit problems.

    Have you validated that the issue follows bad units? (i.e. install a bad part on a known good board)

    If you have a schematic you can share as well that could be helpful to begin to ask more probing questions to determine if the units are somehow being damaged in circuit.
  • 0 in reply to Kevin Duke
    Prodigy 110 points

    Hi Kevin,

    I'm not able to share a schematic at this time.

    Many of the failures related to low input impedance on digital inputs were measured before power was actually applied to the part.

    I can't really speak to the percentage of bad units compared to the entire population since it hasn't been confirmed by our customer that the DAC is the root cause.

    It could be useful to try some newer parts on failing units to see if it resolves the failure that the customer is seeing.

    One of our senior buyers indicated that the DA7725N went obsolete in 2011.

    Is this true?

    Thanks,

    Mark

  • 0 in reply to Mark Tillmann
    TI__Mastermind 46290 points

    Mark,

    The DAC7725 Product Folder (www.ti.com/.../DAC7725) is still marked as active so I do not believe it is obsoleted, I have also seen builds since 2011 when I was searching for the top side markings you shared in the original post. However the stocked volumes are very low. I can check more with our planning teams to see what the reason is behind the low stock and get back to you, it may just be that this product is consumed in very low volumes at this point so a standing stock is not maintained and instead units are produced based on what orders we have in the backlog.

  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Mark,

    Someone with deeper access / experience with SAP found these parts for me. This was indeed made in 2011, and apparently in May - not June.

    Concerning any confusion on obsolescence I am triple checking that with one other internal resource.
  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Mark,

    As I mentioned I've checked this obsolescence topic from every angle possible and the device is positively not obsoleted from TI. I cannot find any reason concerning why or how that would have been communicated.

    Please let me know how you would like to proceed.
  • 0 in reply to Kevin Duke
    Prodigy 110 points

    Hi Kevin,

    One of our buyers showed me a screen shot of DAC7725N/750 as being obsolete in Silicon Expert.

    Do you know why a company like ARROW or Rochester Electronics would be providing parts that are over 7yrs old if new parts are being actively built?

     

    Thanks,

    Mark

  • 0 in reply to Mark Tillmann
    TI__Mastermind 46290 points
    Mark,

    I do not know the mechanisms with which Arrow or Rochester Electronics would have in place for handling old material. I can see builds from TI within this year though, so we are certainly still producing new material.
  • 0 in reply to Kevin Duke
    TI__Mastermind 46290 points
    Mark,

    Is there anything else you would like help with on this topic?

    I can try to dig further into the practices of your distributors if you're having challenges getting answers to that on your side.

    If there is nothing else you want help with at this time, I would like to mark this thread as closed. Should more come up, you can re-activate the thread as long as that post is within 2 weeks. If beyond 2 weeks, you can click on "Ask a Related Question" to continue the discussion with me or someone else on my team.