5.9.3. Guideline: Voltage-Referenced I/O Standards Restriction
- If you use a VREF group for voltage-referenced I/O standards, connect the VREF pin for that group to the appropriate voltage level.
- If you do not use all the VREF groups in the I/O bank for voltage-referenced I/O standards, you can use the VREF pin in the unused voltage-referenced groups as regular I/O pins.
- The VREF pins are shorted together within the same I/O bank. If you use multiple VREF groups in the same I/O bank, you must power all the VREF pins with the same voltage level.
For example, if you have SSTL-2 Class I input pins in I/O bank 1 and you place them all in the VREFB1N group, you must power VREFB1N with 1.25 V. You can use the remaining VREFB1N[1..3] pins, if available, as I/O pins.
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