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Altera_Forum's avatar
Altera_Forum
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18 years ago

Connecting unused pins

Hello everyone, I have a design using a Cyclone III, with some unused pins. I wonder what would be the best recommendation about what to do with these pins. By default Quartus reserve these p...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

Generally I set unused pins to"output driving ground".

Be totally sure that the unused pins are not connected to VCC or external logic on your PCB!

Ground bounce reduction is always a good thing and the extra "GND" pins can help with noise imunity when routing.

Setting unsued pins to "input tri-stated" ensures that you will not have contention with external devices so can be of use.

Personally, I wouldn't go down the route of drivings logic '1' from your device and using pull-ups to VCC.