Subject: RE: [IBIS-Users] IBIS model Error
From: Birendra Rana (birendra.rana@wipro.com)
Date: Wed Aug 13 2003 - 23:58:56 PDT
Hi,
Such errors are encountered when the IBIS model is not generated
properly. One reason of getting this kind of error, as per my
experience, is when the ramp tables haven't captured the full waveform.
The ibischk utility takes the 'not fully settled' final value of the
ramp as the stable end value and compares with the IV table DC end point
and flags an error or warning depending on how big is the difference.
Because of this reason I have seen errors/warnings normally flagged for
one end point.
Muthu Lakshmi's error reports however have large difference at the two
end points which means the problem lies else where.
Regards,
Birendra
-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On
Behalf Of Allen Chao
Sent: Thursday, 14 August 2003 2:08 AM
To: erik.van.der.ven@philips.com; KMuthulakshmi@scmmicro.co.in;
ibis-users@eda.org
Subject: RE: [IBIS-Users] IBIS model Error
Hi IBIS experts,
I have the same problem as Muthu Lakshmi. I don't really understand how
the parser calculated the DC end points from the IV table... If anyone
can kindly show me how it works or know where to find the information on
the internet, it will be greatly appreciated.
Thanks in advance,
Allen Chao
-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of erik.van.der.ven@philips.com
Sent: Monday, July 28, 2003 4:10 AM
To: KMuthulakshmi@scmmicro.co.in; ibis-users@eda.org
Subject: Re: [IBIS-Users] IBIS model Error
Hello Muthu Lakshmi,
I think there is something wrong with your IBIS model. The DC end points
calculated from the I-V tables should match the V-T end points (logic
levels). If the error is within 2% you should get a warning, otherwise
an error. The difference you mention is very big.
The DC end points are calculated from the I-V tables (therefore you
don't see the end points of the V-T table). The I-V tables are derived
by sweeping a voltage at the output and measuring the resulting current.
By applying a certain load the voltages from the logic high and low
level are calculated from the pull-up and pull-down curve (and of course
they should be near the waveform end point voltages). The V-T data is
used to describe the transition between the logic levels calculated from
the I-V data.
I would suggest that you contact Cypress to ask if this model is OK.
With kind regards,
Ir. Erik van der Ven
Room DB1032
Business Line Networking Infrastructure
Philips Semiconductors BV
Gerstweg 2
6534 AE Nijmegen
The Netherlands
Phone: +31-24-3534334
Sent by:
owner-ibis-users@eda.org
07/28/03 05:32 AM
To: ibis-users@eda.org
cc: (bcc: Erik van der Ven/NYM/SC/PHILIPS)
Subject: [IBIS-Users] IBIS model Error
Classification:
Hi All,
I need IBIS expert's advice on the following.
I get the following warning when checking the IBIS model.
Warning - Model bp_usb_hs: The [Rising Waveform]
with [R_fixture]=45 Ohms and [V_fixture]=0V
has TYP column DC endpoints of 0.00V and 0.38v, but
an equivalent load applied to the model's I-V tables yields
different voltages ( 1.14V and 1.06V),
a difference of 99.99% and 64.28%, respectively.
Warning - Model bp_usb_hs: The [Falling Waveform]
with [R_fixture]=45 Ohms and [V_fixture]=0V
has TYP column DC endpoints of 0.00V and 0.38v, but
an equivalent load applied to the model's I-V tables yields
different voltages ( 1.14V and 1.06V),
a difference of 99.99% and 64.28%, respectively.
Warning - Model bp_usb_hs: The [Rising Waveform]
with [R_fixture]=45 Ohms and [V_fixture_min]=0V
has MIN column DC endpoints of 0.00V and 0.37v, but
an equivalent load applied to the model's I-V tables yields
different voltages ( 1.09V and 0.93V),
a difference of 99.99% and 60.23%, respectively.
Warning - Model bp_usb_hs: The [Falling Waveform]
with [R_fixture]=45 Ohms and [V_fixture_min]=0V
has MIN column DC endpoints of 0.00V and 0.37v, but
an equivalent load applied to the model's I-V tables yields
different voltages ( 1.09V and 0.93V),
a difference of 99.99% and 60.23%, respectively.
Warning - Model bp_usb_hs: The [Rising Waveform]
with [R_fixture]=45 Ohms and [V_fixture_max]=0V
has MAX column DC endpoints of 0.00V and 0.39v, but
an equivalent load applied to the model's I-V tables yields
different voltages ( 1.77V and 1.83V),
a difference of 100.00% and 78.72%, respectively.
Warning - Model bp_usb_hs: The [Falling Waveform]
with [R_fixture]=45 Ohms and [V_fixture_max]=0V
has MAX column DC endpoints of 0.00V and 0.38v, but
an equivalent load applied to the model's I-V tables yields
different voltages ( 1.77V and 1.83V),
a difference of 100.00% and 79.26%, respectively.
Please tell me the impact of this warning in simulation. I use XTK for
the simulation. Eventhough the rise and fall VT curve values range from
0V to 0.38V in the IBIS model, I get 1.04V to 1.14V wave form. How is
this related with this. I am using Cypress "CY7C65640" hub controller's
IBIS model.
Awaiting your earliest reply.
Note: One IBIS parser gives the above warnings and another parser gives
them as Errors.
I do not know whether files can be attached with this mail. If it
is OK, I can send the IBIS model.
thanks & regards
K.Muthu Lakshmi (KML)
SCM Microsystems (India) Pvt. Ltd.
email: KMuthulakshmi@scmmicro.co.in
Web: www.scmmicro.com
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