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AR# 13669

Virtex-II - What are the input and output capacitance values for a particular package?


Keywords: I/O, pin, parasitic

What are the input and output capacitance values for a particular Virtex-II package?


The Virtex-II Platform FPGA Data Sheet lists a maximum "Cin" value of 10 pF based on device characterization. Refer to Module 3: DC and Switching Characteristics -> DC Characteristics Over Recommended Operating Conditions table at:

You can find capacitance values that stem from process models in the IBIS file. "C_pkg" is a lumped approximation of the package capacitance, and "C_comp" is the capacitance of the die. For rough calculations, you can add these values to determine the total pin capacitance.

To accurately model the behavior of any signal, you should perform IBIS simulation. IBIS models for Xilinx devices can be found at:

1. Select the tab for the family you want to use. If you do not see the tab, select the family from the Device List drop-down.
2. Under Data Files, select IBIS Models.
3. Select the Device Models tab on the left side of the page.
4. Under IBIS Models, select the family you want.
5. On the IBIS Models page, click the IBIS Models link.
6. Sign in to Xilinx. If you are new, select the Create Account button.
7. The File Download dialog box will appear. Open or Save the zip file.

AR# 13669
Date 04/07/2009
Status Active
Type General Article