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Altera_Forum
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14 years ago

Unused REFCLK and GXB Pins

The Cyclone IV GX Schematic Review Worksheet says to tie all unused REFCLKn pins to GND through a 10K resistor, and the unused REFCLKp pins to GND through a 10K resistor. The same goes for unused GX...
Altera_Forum's avatar
Altera_Forum
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14 years ago

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Is there any reason why I can't connect all of these pins directly to GND, especially that they are all of them strictly input pins.

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The logic levels on these pins are not ground referenced, i.e. the input common mode voltage, Vicm, is not zero. Use a resistor.

Cheers,

Dave