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AR# 22117

Virtex-E/-II/-II Pro/-4 - What is the default I/O standard?

Description

If I do not specify an I/O constraint on the user I/Os, which I/O standard will be selected?

Solution

Single-ended standard:

For Virtex, Virtex-E, and Virtex-II devices, the default I/O standard is LVTTL, 12mA, Slow slew rate.

For Virtex-II Pro and Virtex-4 devices, the default I/O standard is LVCMOS 2.5V, 12mA, Slow slew rate.

Differential I/O standard:

Virtex devices do not support differential I/O standard.

To instantiate the differential I/O standard in Virtex-E devices, refer to the data sheet available at:

http://www.xilinx.com/xlnx/xweb/xil_publications_display.jsp?category=Data+Sheets
Navigate to FPGA Device Families -> Virtex-E -> "Virtex-E 1.8V FPGA Complete Data Sheet (All four Modules)" (ds022.pdf).

For Virtex-II devices, the default differential I/O standard is LVDS 3.3V.

For Virtex-II Pro and Virtex-4 devices, the default differential I/O standard is LVDS 2.5V.

AR# 22117
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article