Ultra low voltage IO pins support on 5SGXMA3K3F40C4

HI @LH12

May i know you are using as input or output?
If as input, what is the upstream device VOH min/max?
If as output, what is the downstream device VIH min/max?

Then, refer to Table17 of datasheet (https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/stratix-v/stx5_53001.pdf)

Check for an IO standard that best meet your requirement.