Specifications

Development System Reference Guide www.xilinx.com 293
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Chapter 17
IBISWriter
The IBISWriter program is compatible with the following families:
• Virtex
™
, Virtex
™
-E
• Virtex
™
-II
• Virtex
™
-II Pro, Virtex
™
-II Pro X
• Virtex
™
-4
• Virtex
™
-5 LX
• Spartan
™
-II, Spartan
™
-IIE
• Spartan
™
-3, Spartan
™
-3E, Spartan
™
-3L
• CoolRunner
™
XPLA3, CoolRunner
™
-II
• XC9500
™
, XC9500XL
™
, XC9500XV
™
This chapter describes the IBISWriter program. This chapter contains the following
sections:
• “IBISWriter Overview”
• “IBISWriter Syntax”
• “IBISWriter Input Files”
• “IBISWriter Output Files”
• “IBISWriter Options”
IBISWriter Overview
The Input/Output Buffer Information Specification (IBIS) is a device modeling standard.
IBIS allows for the development of behavioral models used to describe the signal behavior
of device interconnects. These models preserve proprietary circuit information, unlike
structural models such as those generated from SPICE (Simulation Program with
Integrated Circuit Emphasis) simulations. IBIS buffer models are based on V/I curve data
produced either by measurement or by circuit simulation.
IBIS models are constructed for each IOB standard, and an IBIS file is a collection of IBIS
models for all I/O standards in the device. An IBIS file also contains a list of the used pins
on a device that are bonded to IOBs configured to support a particular I/O standard
(which associates the pins with a particular IBIS buffer model).
IBISWriter supports the use of digitally controlled impedance (DCI) for Virtex-II input
designs with reference resistance that is selected by the user. Although it is not feasible to
have IBIS models available for every possible user input, IBIS models are available for I/O
Standards LVCMOS15 through LVCMOS33 for impedances of 40 and 65 ohms, in addition