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RyusukeYOKOYA's avatar
RyusukeYOKOYA
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7 months ago

Re: Inquiry Regarding Cyclone V IBIS Model Definitions and Updates

Dear Intel Support Team, I hope this message finds you well. I am currently conducting IBIS simulations for the Cyclone V FPGA, specifically for the part number 5CGXFC9C6F23, and I have a few quest...
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FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
6 months ago

Hi,
thanks for correction. Now I get your point.

lvcmos_xxx_d2xx Ibis I/V curves don't look like 2 mA current strength, according to datasheet specification (0.2 V max. voltage drop at nominal current) it rather looks like 8 mA. Unfortunately I have no Cyclone V board at hand and can't check if lvcmos_d2 I/O standard is setting current strength that high or if it's only an IBIS file error.

I can tell that e.g. Cyclone 10LP has consistent current strength settings and IBIS files.

In contrast, the relation of Cyclone V lvcmos30 and lvttl30 I/V curves looks consistent. See below a visualization.

Best regards
Frank

  • RyusukeYOKOYA's avatar
    RyusukeYOKOYA
    Icon for New Contributor rankNew Contributor
    6 months ago

    Hi Frank,

    Thank you very much for taking the time to review the details and for providing additional insights.

    I also find it difficult to determine whether this behavior is part of the intended specification or simply an error in the IBIS file. Given the ambiguity, I would appreciate it if an Intel employee could help clarify this point.

    Thanks again for your support.

    Best regards,
    Ryusuke YOKOYA

    • FvM's avatar
      FvM
      Icon for Super Contributor rankSuper Contributor
      6 months ago
      Hi,
      I got hold of an old Cyclone V based PCA and was able to measure drive strength of lvcmos 3.3V output. I found that is nearer to lvttl_d4 than lvttl_d16, in other words, just what we would expect for lvcmos_d2. Suggests that lvcmos_d2 spec in Cyclone V IBIS file is wrong and doesn't represent actual device behaviour.

      Regards
      Frank