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UCD3138: Non-monotonic Notes when running UCD3138 IBIS model

Guru 65920 points
Part Number: UCD3138

Hello

When running the IBISCHK on the UCD3138 IBIS model(https://www.ti.com/lit/zip/slum586, the following Notes are popped. Could you please help explain what these NOTES mean?

Thanks

Yihe

  • Yihe, I looked at the actual numbers in the file, and they are monotonic, but only barely.  It looks like the ibis program is just going down the columns and looking at variation in slope.  The problem with that is that:

    The voltage steps driving everything are not even.  There's a big step in voltage and then a small one.  So there's a big step in current, and then a small one.  

    So I'd say everything is fine.  Here are graphs of voltage and typical to show what I mean:

    You can see that the uneven voltage steps lead to uneven steps on the current measurements.  And you can see that when the slope decreases significantly, that seems to trigger the note from ibis.  It looks like if you graphed current vs voltage, you would get a nice smooth line.  

    I probably didn't need to dig in that much, but I couldn't resist.  

  • Hello Ian

    Could you share the graphics since I do not see the them in the previous post?

    Thanks

    Yihe

  • Yihe, if you looked at them right when I posted they didn't show up.  However, I've edited it since then, and I can see them up there.  If you can't see them now, let me know and I'll try to fix it.  

  • Hi Ian

    Thank you. I can see the figures now , but How do you get the Y-axis data for the two figures? They do not look from file directly.

    Regards

    Yihe 

  • I put the file into excel, and the row numbers corresponded to the line numbers.  That's actually the X axis.

    The Y axis definitely corresponds to the data from the file:

    | Voltage I(typ) I(min) I(max)

    -3.3 -0.000161608 -9.56727e-05 -0.000239472
    -1.7754 -0.000594687 -0.000322629 -0.000918274

    .....

    -0.4092 -0.0176307 -0.0128072 -0.0223204
    199 -0.2706 -0.0118803 -0.00854971 -0.0151232
    200 -0.2409 -0.0106218 -0.00762641 -0.0135373
    201 -0.132 -0.00591771 -0.00421208 -0.00757488
    202 -0.1221 -0.00548254 -0.00389919 -0.00702061
    203 -0.0231 -0.00105446 -0.000743786 -0.00135551
    204 -0.0132 -0.000603579 -0.000425392 -0.000776205
    205 -0.0033 -0.000151156 -0.000106443 -0.000194462


    I added the line numbers to the relevant lines in the file - this is from the excel spreadsheet.