RE: IBIS model creation

Stephen,

The data are tabulated after the vcc-relative calculation, vtable=vcc-vout. After the calculation, the data have the same range.
For a pullup curve, the following table may help:

                        (vout) (vtable)
                        sweep vcc-relative
corner vcc range range
------ --- ----- -------------
min 3.0 -3.6 > 6.3 6.6 > -3.3
typ 3.3 -3.3 > 6.6 6.6 > -3.3
max 3.6 -3.0 > 6.9 6.6 > -3.3

Regards,
Ross
--------------
Ross Pryor
Nortel Networks
Billerica, MA
(978) 288-3811
ESN 248-3811
rpryor@nortelnetworks.com

-----Original Message-----
From: Stephen Nolan [mailto:s-nolan1@ti.com]
Sent: Wednesday, January 05, 2000 1:31 PM
To: ibis-users@eda.org
Subject: IBIS model creation

I've been reading the draft version of the "IBIS FORUM I/O BUFFER MODELING
COOKBOOK - Revision 2.0X (under development)"

In the section entitled "Making Pullup and Power Clamp Sweeps Vcc Relative" it
states that you should make your three sweeps Vcc relative. Example: min=-3.6 to
6.3, typ=-3.3 to 6.6, and max=-3.0 to 6.9.

In this case, there would be table data created for the min column from -3.6 to
-3.3 where no typ data exists. Also, there would be data in the max column from
6.6 to 6.9 where no typ data exists. In those ranges, the typ column would have
to include NAs. Is this legal?

The IBIS spec (Version 3.2) says:
"NA" can be used for currents in the typical column, but numeric values MUST be
specified for the first and last voltage points on any I-V table.

As I read this, the typ table would have NA values for both the first and last
voltage points on the I-V table, by following this method.

And the example given in the IBIS spec ranges ONLY from -5 to 10 V and does not
include the additional data suggested by the "Making Pullup and Power Clamp
Sweeps Vcc Relative" section of the Cookbook.

Thanks.

--
Regards,
Stephen M. Nolan