What affects a microcontroller IO's VOH_min and VOL_max?
For a given specified value of \$I_{OL}\$ and \$I_{OH}\$, the actual (not specified) values of \$V_{OL}\$ and \$V_{OH}\$ are subject to the usual influences: temperature, manufacturing variation, supply voltage, aging, packaging resistance differences, and so on. Which of these might be a &quot;major&quot; contributor depends a great deal on the specific device design, fabrication, and usage.