Forum Discussion
Altera_Forum
Honored Contributor
Honored Contributorwill Cyclone III work with unconected VCCA PLL ??
I actually made e board already and didn't connected thous VCCA PLL pins and now my board don't work (I can't program it and software all time is saying "can't access JTAG chain" is that because...
Altera_ForumHonored Contributor
Honored ContributorVCCA is required for a Cyclone III class product because:
1. It's a 65nm product. Smaller process geometries require more technical discipline with respect to voltage (affects the IC designer and the board designer equally). 2. The Cyclone III PLLs are far more sophisticated than Cyclone II. In order to keep the PLL jitter superior to alternative clock sources on a board, it needs its own, clean power source. For future reference, you can just take the schematics from the starter kits: http://www.altera.com/products/devkits/altera/kit-cyc3-starter.html#documentation and save yourself a lot of headaches experimenting with what Altera means by the word "required". Out of curiosity, did you spend more than $200 in your time and money to build this home baked board? GG
