RE: [SI-LIST] : Bad IBIS models!

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From: Dan Bostan (dan@Corvia.com)
Date: Wed Mar 15 2000 - 13:12:59 PST


Kim,
Could you please provide a couple of embarrassing examples of companies that
provide faulty IBIS models?

Dan Bostan
Corvia Networks

-----Original Message-----
From: Kim Helliwell [mailto:khelliwe@acuson.com]
Sent: Wednesday, March 15, 2000 12:54 PM
To: si-list@silab.eng.sun.com
Subject: [SI-LIST] : Bad IBIS models!

Are any component vendors reading this list? I'm frustrated
with some of the excuses for IBIS models some of them
(naming no names) distribute on the web and elsewhere.

Here are the problems I've seen so far:

1. Models that don't have a complete pin map
2. Pin map does not match the data sheet.
3. Files that specify all the pins, but some of the models referenced
   don't exist in the file
4. Driver models that don't have any rise and fall curves.
5. dv/dt values that are *GIVEN* as 0.00000/0.00000.
   (This is totally unacceptable by my signal integrity tools)
6. dv/dt values that are *GIVEN* as -x.xxxx/y.yyyy
   (that is, negative values specified; also not accepted by
   my SI tools)
7. Min/Typ/Max values or curves that are scrambled
   ( Typ > Max, Min > Typ, Min > Max)
8. VI and clamp curves that are discontinuous.

My word to vendors: customers that use IBIS models are not that
easily fooled. We use ibischk3, we look at the curves with a graphing
utility, and we have conversion programs that choke on one or more
of these problems. We can look at a model and pretty quickly tell
whether it is a good or a bad one. And it's pretty clear over time
which vendors consistently provide good models, and which ones obviously
aren't interested in providing good models and consequently do a
half-assed job on them.

We're watching, and we know who you are!

Of course, vendors that don't supply models at all don't
even rate this much attention.

OK, I feel better now. Anyone else?

-- 
Kim Helliwell
Senior CAE Engineer
Acuson Corporation
Phone: 650 694 5030  FAX: 650 943 7260

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