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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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19 years ago

I recently spent a very long time debugging a problem that turned out to be an unconnected PLL power supply. The design used no PLLs and almost completely passed through qual testing (temp cycling and everything) when we found a problem with a completely unrelated I/O cell tristate control. An embarrassingly long time passed between discovering the problem and figuring out what was causing it.

NEVER NEVER NEVER leave a PLL power supply pin unconnected.