I've looked in the datasheet looking for my answer to no avail.
Just wondering is there any big differences, or anything I need to know when running at 1.8v vs 3.3v?
May i know what do you meant by running at 1.8V / 3.3V? Are you saying the VCCIO? I/O Standard? or what?
Every VCC.
For some MCU's I use, they are only capable of USB when running at 3.3 or 5v, due to the clock requiring that voltage.
I'm just wondering if there is any similar nuances with the Max II.
I am assuming you are saying the capable of MAX II to interface with 5.0V and 3.3V. If it so, yes it can be. You may refer to link below for more information about it.
https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/max2/max2_mii51009.pdf
