The datasheet for Cyclone 10 LP says:"All VCCA pins must be powered to 2.5 V (even when PLLs are not used) and must be powered up and powered down at the same time." Can I consequently leave them powered down all the time (I do not use any PLL), i.e. connected to GND? If the answer is yes, should I also connect VCCD_PLL to GND?
I concede there's always a way to misunderstood a clear specification if you try hard enough. The "and" conjunction in the middle of the quoted sentence tells you that both conditions should be fulfilled. If you also want to know why, you may step back a few lines in the device handbook where it says:--- Quote Start --- The POR circuit of the Intel Cyclone 10 LP device monitors the VCCINT, VCCA, and VCCIO (of banks 1, 5, 6, and 8) that contain configuration pins during power-on. --- Quote End --- In other words, the device won't start operation before all mentioned power pins are up. I guess this answers your question.