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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...
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Altera_Forum
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14 years ago

That's interesting because I just saw in one of the Cyclone IV demo boards, they tied both REFCLKn and REFCLKp together directly to ground.

Thinking more about it, I don't believe those pins have any OCT because you are required to put the termination outside (page 1-28 of the device handbook.)

The OCT issue still exists with the GXB_RX pins though.

Does this sound like a correct reasoning?