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                           IBIS Model Usage
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Contents:

1) General Suggestions

2) Configuring the PIN parameter

3) Selecting the required package

4) PCI related

5) Calculating the max/min source/sink current from the IBIS models

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1) General Suggestions
---------------------------------
It is always good to open the IBIS model in a text editor and look for any
model specific intructions that might be included. Since these appear as
in-line comments in the model, simulators will ignore them by default.


2) Configuring the PIN parameter (Not applicable to ProASICplus)
---------------------------------
Each Actel IBIS model contains a pin named ALLIO. This pin can serve as a
signal pin during board level simulations. Simply replicate the pin as
many times as needed to suit your design.


3) Selecting the required package (for all models)
---------------------------------
The IBIS model(s) contain package parasitics under R_pkg, L_pkg, C_pkg.
The model(s) usually have information for more than one package. All package
data except for one will be commented out by default. The pipe (|) symbol in 
the first column is the comment character. Please uncomment the appropriate
package before starting the simulation.
example:
|
R_pkg            0.800               NA                  NA          | FG896
L_pkg            6.19nH              NA                  NA          | FG896
C_pkg            3.59pF              NA                  NA          | FG896
|
|R_pkg            0.711               NA                  NA          | FG676
|L_pkg            5.75nH              NA                  NA          | FG676
|C_pkg            3.07pF              NA                  NA          | FG676
|
|R_pkg            0.566               NA                  NA          | BG456
|L_pkg            7.49nH              NA                  NA          | BG456
|C_pkg            2.18pF              NA                  NA          | BG456
|


4) PCI related (Only ProASICplus PCI models)
---------------------------------
According to the PCI spec the Vref and Vmeas parameters are different depending
on the edge under consideration. So for the PCI models Vref and Vmeas
parameters are commented out and are given seperatly for both edges. Please
uncomment the values corresponding to the required edge.

5) Calculating the max/min source/sink current from the IBIS models
---------------------------------

The brief description below is the procedure to get the MAX source/sink current 
from the IBIS model. These are not guaranteed values as results may vary slightly 
from device to device.  For detailed information about background and usage of 
IBIS models, please refer to the application note: 
http://www.actel.com/appnotes/Ibis_AN.pdf.

Positive current is defined as current flowing into the device.
The voltage in IBIS model tables are derived from the equations below:

	Vtable = VCC - Voutput   (in Pullup section for source current)
	Vtable = Voutput         (in Pulldown section for sink current)

To get the MAX source/sink current at the correct operating voltage, you need to 
consider the Min/Max value of VOH/VOL from the DC Specification listed in your 
devices corresponding datasheet:

	Vtable = VCC - VOH(Min)		(for MAX source current)
	Vtable = VOL(Max) 		(for MAX sink current)

For example, the DC Spec in the SX-A datasheet shows that VOH(Min) is 
2.4V at 3.3V LVTTL,  so the corresponding WORST case MAX source current, I(min), 
is -35mA as shown below at Vtable = 3.3V – 2.4V = 0.9V.  The BEST case MAX source
current corresponds to I(max) which is equal to -50.9mA at Vtable = 0.9

 [Temp Range]   25.0000             0.1250k             -54.0000 
 [Voltage Range]3.3000V             3.0000V             3.6000V
 [Pullup]
 | voltage     I(typ)              I(min)              I(max)
   0.7000      -34.9100mA          -28.4922mA          -41.0565mA
   0.8000      -39.1200mA          -31.8780mA          -46.0863mA
   0.9000      -43.1300mA          -35.0757mA          -50.9141mA <---
   1.0000      -46.9400mA          -38.0952mA          -55.5197mA
   1.1000      -50.5500mA          -40.9365mA          -59.9031mA

-Actel Corporation
May 29, 2002