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SN54AHCT00: Need IBIS model

Scott Asher
Intellectual 500 points
Part Number: SN54AHCT00

Hello, Can you provide an IBIS model for the SN54AHCT00J? If one is not available, can you provide a model of another part that would provide close to the same simulation results as the SN54AHCT00J? If so, what would the differences be?

Thanks,

Scott

  • 0
    TI__Guru 62930 points
    Scott,
    The ibis model for the commercial variant can be used for representative performance.
    Our modelling team has evaluated effects for package parasitics, and concluded that in most cases the parasitics are too pessimistic. All new IBIS model will have generic parasitic values and will not vary by package type.

    The commercial version of the IBIS model is available here: www.ti.com/.../toolssoftware

    If this answers your question, please click "Verify it as the answer"
    Regards,
    Wade
  • 0 in reply to Wade Vonbergen
    Intellectual 500 points
    Hi Wade, Thanks for the info! I have some follow up questions on this.

    So are you saying that it is the same die in both the 54 as compared to the 74 part? And that the only difference between the 54 and 74 parts is the package parasitics?

    If this is is true, then why does the datasheet report the same tPLH/tPHL max value of 8ns for both the 54 and 74 part? The 54 part is rated to 125C where the 74 part is only rated to 85C. If it was the same die in both, I would think the tPLH/tPHL max would be greater than 8ns for the 54 part since the same die would be slower at 125C as compared to at 85C.

    And I also assume that the min value of dV/dt_r and dV/dt_f ramp rates in the IBIS model for the 74 part is for only 85C temp and not all the way up to 125C, right? So in this case, how can I use the IBIS model for the 74 part to simulate what my slowest PCB trace flight time delays would be for the 54 part at its max temp of 125C?

    Thanks,
    Scott
  • 0 in reply to Scott Asher
    TI__Guru 62930 points
    They are from the same design, but may differ in wafer fab flows. However, at nominal conditions, they will perform the same.

    As far as the discrepancies in propagation max delays being the same with different temperatures.
    My only explanation for this, is that they were independently characterized and the commercial limits are very conservative. The engineer who released the military version chose to keep same limits as commercial.

    IBIS models have quite a bit of variability to them (at least in how they are generated), and they are not considered sign-off models.
    For example many models are empirically generated in the lab. This is based on just a few units and does not encompass the entire process spread. Some are generated from simulations (as this one is), and will cover process.
    Unfortunately, we do not have the capability to simulate many of the older designs to military temperature extremes and re-create the IBIS model.

    The models are intended for signal integrity analysis, and not timing analysis. Having a somewhat slower slew at 125c versus the 85c should only improve the signal integrity, and not worsen it.

    Regards,
    Wade