In Vivado Design Suite 2015.1, THE XADC Wizard has incorrect alarm limits for some of the -2L devices.
For example in (DS191) the Vccint and Vccbram limits for the -2L are given as Min = 0.93V, Typ = 0.95V and Max = 0.97V.
However in the Wizard the lower limit is 0.87 - 0.9V for Vccint and 0.95 - 1.0V for Vccbram and the Upper Limit is 0.91V - 0.93V for Vccint and 1.0 - 1.05V for Vccbram.
As a result, the alarm limits do not match the data sheet limits.
The Data sheets limits are correct and the Wizard limits are incorrect.
This is also true for the Virtex-7 -2L devices.
This is a known issue with the Wizard and will be fixed in a future release of the Wizard.
To work around the issue, you can change the limits in the VHDL code that is generated by the Wizard and include the HDL in the project instead of the XCI file.
The lines that need to be changed are the Vccint and Vccbram upper and lower alarm limits.