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Altera_Forum
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19 years ago

VCCA_PLLn

I know the Stratix II device handbook says I must connect the VCCA_PLLn even if I'm not using PLLn. But do I really have to? What will happen if I don't? I want to save all the power I can.
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Altera_Forum
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18 years ago

Just a clarifying post here....

Both VCCA and vccd for the PLLs must be connected to supply voltages. The problem I referred to earlier was from an unconnected VCCD for one of the PLLs.

Remember, this design that I was working on didn't even use PLLs. None. All we did was leave the VCCD from one of the PLLs unconnected and it turned into a two month debugging adventure. As I mentioned earlier, the problem manifested in an occasionally faulty tristate control in a completely unrelated I/O cell.

Just follow the pin connection guidelines, hook up PLL VCCA and VCCD pins and save yourself a debugging nightmare.