Is there a longer delay on VREF pins when used as I/O compared to general purpose I/O pins in Cyclone-series devices that support dual-purpose VREF pins?

Description

Yes, there is a longer delay on VREF pins when used as an I/O pin compared to a general purpose I/O pin in Cyclone®-series devices that support dual-purpose VREF pins.

The pin capacitance is higher on VREF pins than general purpose I/O pins, thus you should avoid placing fast edge rate signals such as clocks on these pins, and avoid using these pins in buses since the I/O timing will not be consistent with the rest of the bus.

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