Re: Combining IBIS models of the same part from different vendors

From: Lynne Green <lgreen@cadence.com>
Date: Tue Jul 03 2001 - 16:26:51 PDT

Kim,

You should be very careful. Two parts may have the same data sheets, but
the edge
rates may differ by a factor of 3 or more (and signal integrity will be
correspondingly
different!).

If possible, SI should be checked using the IBIS model from each vendor
that you
use as a source for the part. At the least, check the fastest and slowest
IBIS
drivers you can encounter on each net.

It is probably safest (from a design data management perspective) to keep
the IBIS
files separate, and "sweep" the model files in the simulation tool.

-Lynne

At 03:14 PM 7/3/2001 -0700, you wrote:
>One of the difficulties in the IBIS world is: if you are using a part that
>you buy from several
>vendors, and they each give you an IBIS model for the part, how do you
>combine these
>files into some sort of composite models (assuming that is desirable at all).
>
>Now, it's easy to look at typ, min, max values for caps and voltages, and
>figure out
>what to do. Harder is combining typ, min, and max pullup and pulldowns,
>or VT curves.
>
>What I'm looking for is a "best practice" for this situation: if you've
>faced this situation, how have
>you dealt with it?
>
>Of course, maybe nobody has faced this yet, because the other difficulty,
>of course, is
>finding a part, any part, that has multiple suppliers that all provide
>IBIS models for them :-)
>But we won't go there this time!
>
>
>Kim Helliwell
>Apple Computer
>kimgh@apple.com
>408 974 9936

 

Received on Tue Jul 3 16:28:19 2001

This archive was generated by hypermail 2.1.8 : Fri Jun 03 2011 - 09:53:47 PDT