For the -1LI, -2LI, and -2LE speed grades, VCCINT can operate at 0.72V versus 0.85V/0.90V for VCCBRAM/VCCINT_IO. It is thus necessary to separate those rails onto different planes. Plane design for VCCINT and VCCBRAM/VCCINT_IO should be sized in such a way as to provide the required amount of current/power with minimal IR drop to ensure that the voltage rails meet the data sheet specifications.