The DIFF_TERM attribute activates internal differential termination for differential inputs. Are there any VCCO supply restrictions when using this attribute?
The internal termination is designed to work with a VCCO supply of 2.5V. A VCCO supply other than 2.5V results in a non-ideal termination, and is not recommended or supported.
Virtex-II Pro/Virtex-4/Virtex-5 SPICE models can be used to examine the effect of Process, Voltage, and Temperature variations on differentially terminated inputs (model = "LVDS_25_DT"). The SPICE models can be downloaded in the Download Center at: