RE: [SI-LIST] : IBIS models

Roy Leventhal (Roy_Leventhal@mw.3com.com)
Mon, 30 Aug 1999 08:41:32 -0500

Abe,

Not always so simple and convienient as you indicate. I agree with you for a
device witha few tens of pins. But, for example, for a programmable device with
several hundred pins it's a lot of tedious extra work for every user of the
device. A lack of a proper pin list is just a lazy supplier's way of avoiding
the same distasteful, resource consuming task their customers would find more
cost effective if it were just figured into the price of the part.

IBIS itself offers no real sanctions for non-compliance with any of its
provisions. When the JEDEC committee tried laying down the law to suppliers they
were quickly rendered irrelevant with the use of "supplier controlled,
non-registered data sheets." Talk about a license to do anything at any time to
your product with warning or data.

I still haven't figured out what the disclaimer "Data is for modeling purposes
only - - - use at own risk - - - not guaranteed," etc. Just what do suppiers
think I should do to proceed with my design, improve its insensitivity to normal
process variation, not overstress it, etc.?

I don't get it. I thought that IBIS was an agreement between semiconductor
supplier and software suppliers to provide an improved means for exchanging data
with their customers so that they could all suceed together. How do half-assed
pin list help that objective?

Best Regards,

Roy

Abe Riazi <ariazi@anigma.com> on 08/28/99 11:30:01 AM

Please respond to si-list@silab.eng.sun.com

Sent by: Abe Riazi <ariazi@anigma.com>

To: "'si-list @silab.eng.sun.com'" <si-list@silab.eng.sun.com>
cc: (Roy Leventhal/MW/US/3Com)
Subject: RE: [SI-LIST] : IBIS models

>Mike Mayer Wrote:
>
>I have found several IBIS models that use the [Pin] keyword but only
>model a couple of pins. For example, an octal buffer in a 20-pin
>package that only includes statements for one buffer input pin, one
>buffer output pin, Vcc and Gnd. My reading of the IBIS spec would say
>that this is non-compliant. In Section 5 under "Usage Rules" for the
>[Pin] keyword the first sentence states "All pins on a component must
>be specified.".
>
>1) Am I correctly interpreting the IBIS specification?
>
>2) How common are models of this type?
>
>--
Hi Mike:

What you have described is one of the most common types of model
deficiency I have observed in IBIS models. however, in many cases it is
quite simple to fix this kind of model defect. Frequently, all that is
required to complete the pin mapping section of the model is the
datasheet of the device and an ASCII file editor.

Regards,

Abe Riazi
>ariazi@anigma.com
>

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