Subject: Question on the Sweep range

From: [email-masked] ( Scott Aron Bloom)
Date: Mon, 27 Jun 94 09:39:35 PDT

After reading  all the ibis specs that are available to me, I can not find this
answer anywhere.

For the voltage ranges, version 1.1 and 2.0 specs state:

2) Voltage Ranges:
|    Points for each curve must span the voltages listed below:
|
|       Curve                   Low Voltage             High Voltage
|       -----------             -----------             ------------
|       [Pulldown]              GND - POWER             POWER + POWER
|       [Pullup]                GND - POWER             POWER + POWER
|       [GND Clamp]             GND - POWER             GND + POWER
|       [POWER Clamp]           POWER                   POWER + POWER

Now the question I have is this.  When you are sweeping on the non-typical
voltage, what is the range.  Meaning, if you have a 5 volt power supply, 
with a minimum voltage of 4.5 volts.  Does you sweep for the pullup now go from
-4.5 volts to 9 volts?  or from -5 to 5 as before?

Thanks in advance,

Scott Aron Bloom
InterConnectiX, Inc.

---

From: Arpad Muranyi <[email-masked]>
Date: Mon, 27 Jun 94 10:46:05 PST

Scott,

Since there is only one voltage column for the three cases of current columns in
the IBIS models, in my mind this rule references the typical voltage range.  
Therefore my models all have a -5V to +10V range regardless whether the columns 
are typ., min., or max.

This is actually not a very important issue anyway.  The lab measurements can 
not go that far in most cases.  The main reason we added this rule was to make 
sure that all simulators cover the widest possible range correctly, because they
do not all extrapolate the same way beyond the last data point.  For example, if
your last data point is at -1V, one tool might continue with the last slope, 
another might continue horizontally, and another vertically.  If you had a -2V 
undershoot, you would see very different results.

Arpad Muranyi
Intel Corporation

After reading  all the ibis specs that are available to me, I can
not find this
answer anywhere.

2) Voltage Ranges:

Now the question I have is this.  When you are sweeping on the non-typical
voltage, what is the range.  Meaning, if you have a 5 volt power supply,
with a minimum voltage of 4.5 volts.  Does you sweep for the pullup
now go from
-4.5 volts to 9 volts?  or from -5 to 5 as before?

Thanks in advance,

Scott Aron Bloom
InterConnectiX, Inc.

---

From: "Hobbs, Will" <[email-masked]>
Date: Mon, 27 Jun 94 11:50:52 PDT

Scott,

The soon-to-be-released IBIS Modeling Cookbook says the following:

Note: The IBIS specification calls for the pullup and power clamp diode I-V data
to be referenced to VCC.  To put the data into a table format properly, adjust 
the sweep voltage along with VCC.  For example, the sweep voltage for a 5V part 
under typical conditions would range from -5V to +10V.  For minimum conditions, 
where the VCC was adjusted to 4.75V, the sweep voltage would also have to be 
adjusted -0.25V (i.e., sweep from -5.25v to +9.75v).  Likewise, for maximum 
conditions, adjust the sweep voltage positive along with the VCC.

Will Hobbs
Intel Corp.

2) Voltage Ranges:

Thanks in advance,

Scott Aron Bloom
InterConnectiX, Inc.