VCC_CKLK
pins have the same specifications as the VCCINT
pin, and can only be connected to 1.8 V.
VCC_CKOUT
pins have the same specifications as VCCIO
, and can be connected to either 1.8 V, 2.5 V, or 3.3 V.
For more information, refer to Application Note 115 (Using the ClockLock & ClockBoost PLL Features in APEX Devices).