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SN74LVC2G17DCK IBIS Model and Die Shrink

Ned Dempsher
Intellectual 260 points

Hi TI,

My name is Ned Dempsher and I'm a signal integrity engineer here at L-3 Communications.

We have been using the SN74LVC2G17DCK on one of our products for a number of years. I think since about 2008.

I am being told that there has been a recent die shrink on this part and they would like me to assess if there are any changes to signal integrity on our board with this part's most recent die shrink.

We used an IBIS model for our SI analysis dated August 18, 2003 (Rev. 1.3) when we did our original SI work in 2008. The latest model on your website is dated April 24, 2013 (Rev. 1.4) but the revision log at the top of the IBIS model file states that the only change with the new revision is to add the package component LVC2G17_DRY. The driver behavior appears to be identical between the two models consistent  with the revision log.

Would you be able to let me know:

1. Does the current IBIS model available on your website reflect the latest silicon with the most recent die shrink?

2. If not would I be able to get this model created by you from your SPICE?

3. Could you tell me when the latest die shrink took place?

This is an very expensive product so we don't want to leave anything to chance.

Thanks Very Much TI,

Ned Dempsher

L-3 Communications 

  • 0
    TI__Guru 62240 points
    Hi Ned ,

    Thanks for all the details provided . I contacted my product engineering department and I am told that the change notification expired this March.
    The die shrink strives to retain the char of the device intact and there is no change to the datasheet . the process and layout was changed to shrink the die but currently the DCK doesn't have the new die yet. It doesn't mean that it probably wont happen in the near future though.
    I would refer you to contact the simulation and modeling forum to consult regarding the spice simulation since I do not have the tools to do it .
  • 0 in reply to ShreyasRao
    Intellectual 260 points

    Thanks Shreyas,

    What does this mean "the change notification expired this March..."?

    It looks like you are saying that they try to meet the same characteristics like rise and fall times as the original die when performing a die shrink?

    I'll send a question regarding the model to the simulation and modeling forum now.

    Ned

  • 0 in reply to Ned Dempsher
    TI__Guru 62240 points

    Hi Ned ,

    Every time there is any change associated with the device , TI would issue a product change notification (PCN) along with it to explain what changed. The time limit for any objection with the change recently expired in March I am told. 

    There is no change in the datasheet electrical specs even after the change. If there was any change in the spec values we cannot release this without changing the device name.

  • 0 in reply to ShreyasRao
    Intellectual 260 points
    Thanks Shreyas,

    The one concern I have is that if the rise time decreases this could significantly effect signal integrity while the tpD specification may not change much at all. The tPD is in the datasheet but tRISE is not so I am concerned that the rise time could decrease adversely effecting SI. What do you think?
    Ned
  • 0 in reply to Ned Dempsher
    TI__Guru 62240 points
    Hi Ned ,

    we do not spec the tr and tf on the datasheet , they are heavily dependent on the load (cap load or RC) at the output.
    With die shrink I would think the rise time should not decrease rather stay the same or increase for the same load .