By default, DONE is released in phase 4 of
start-up. DONE indicates that configuration is complete and
all data has been loaded, but some extra clock cycles need to be applied to
ensure the start-up sequence completes correctly all the way to phase 7, End
of Start-up. A conservative number for the clock cycles required after
DONE is 64; this will account for the most common
use cases. An undefined number of clock cycles are added If the bitstream
options LCK_cycle and Match_cycle are set after phase 4
(DONE).