[SI-LIST] Re: Translating a Differential IBIS buffer to XTK format
- From: Umesh Painaik <upainaik@xxxxxxxxxxxx>
- To: Timothy.Coyle@xxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Wed, 17 Jul 2002 09:33:47 -0400
Hi Timothy
Yes if ibis2xtk does not see the ibis cookbook test fixtures it will default
to ramp.
You can use ibis2xtk -no_rfchk option to override this checker.
This checker should only be used if you are absolutely sure if the VT test
fixtures are correct for the technology.
e.g. LVDS, 50 to 1.0 and 50 to 1.4
SSTl2 class I, 25 to 1.25
SSTL2 Class II, 50 to 1.25
PCML, 100 to 3.3V and 50 to 3.3V
These are some examples.
Generally it is a good idea to check the vendor's board termination schemes
to verify if the test fixtures in ibis model ( if out of the ordinary)
makes sense
Hope this helps
Umesh Painaik
Innoveda
-----Original Message-----
From: Timothy Coyle [mailto:Timothy.Coyle@xxxxxxx]
Sent: Tuesday, July 16, 2002 10:28 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Translating a Differential IBIS buffer to XTK format
Hi,
I am running into a problem when I try to translate a LVDS IBIS buffer
to
XTK using IBIS2XTK. The issue is that each time I run the program, it
always defaults to using
the Ramp data, and not the V-T data in the conversion. I get a warning
message in the log file that says, "Required waveform(s) not found,
using
Ramp"
So I asked Innoveda (now Mentor) support for help. They pointed me to
the
IBIS2XTK manual, where it states that for an output model V_fixture has
to
be
within .7V of the rail voltage. Since this is LVDS, I am using V_fixture
of 1.25V. If I change V_fixture to 3.3 V (the supply voltage), then the
V-T data is used.
The V_fixture requirement does not apply to open-ended models. I asked
support if they knew of this issue, and have not heard anything since.
Has
anyone
encountered this problem? Perhaps I am doing something wrong? If not,
does
anyone know of a possible work-around?
Thanks,
Tim
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