RE: SE and diff drivers on same pin

Larry,

It seems to me that you would like to use the [Model Selector] to be able to
switch between the differential and single ended mode of the buffer. You
are
right, this would only be possible if the [Diff Pin] keyword (or a similar)
function could be inside the [Model Selector]. Unfortunately this can't be
done currently. I would suggest to use the comment character before the
line
that defines the pins of interest as differential in the [Diff Pin] section
for
the single ended mode, and no comment character for the differential mode.

I am just curious, are there a lot of devices like this out there? If so,
we
should probably find an IBIS solution for this case. This could be brought
up
in one of the Open Forum meetings, if necessary.

Arpad
============================================================================
==

-----Original Message-----
From: Beal, Weston [mailto:Weston.Beal@COMPAQ.com]
Sent: Wednesday, May 05, 1999 6:51 AM
To: 'ibis-users@eda.org'
Subject: RE: SE and diff drivers on same pin

Larry,

Defining the differential pins with different drivers is no problem. You
just assign the appropriate model in the pin list and then define the pins
as differential in the diff pin block. I think that IBIS allows you to use
model selector and diff pin on the same pins, but it is likely to confuse
half the simulators, or simple not be supported. I've seen this type of
device before in IBIS and the manufacturer defined it as two different
devices. This is your best bet, I think.

Regards,
Weston Beal
Signal Integrity Engineer
Compaq Computer Corp.

                -----Original Message-----
                From: Barnes, Larry [mailto:Larry.Barnes@lsil.com]
                Sent: Tuesday, 04 May, 1999 4:38 PM
                To: 'ibis-users@eda.org'
                Subject: SE and diff drivers on same pin

                I'm trying to construct a model of a SCSI-2 part. SCSI-2
data pins are
                either differential or single-ended depending on what bus is
detected by the
                part.

                I was planning on using the model selector to assign either
the SE or diff
                driver to the correct pin. BUT I am in a quandary where to
place the Diff
                Pin definitions.

                Also the I-V curves of the differential pins are not exact
mirrors of each
                other, so I have set of data available for each side of the
diff driver.

                I guess I could defined two complete components in the file,
one
                single-ended usage and one for differential. But I still
have a question as
                to how to implement the Diff Pin definitions

                Any suggestions would be appreciated.

                Regards,
                Larry Barnes
                larry.barnes@lsil.com
Received on Wed May 5 08:34:29 1999