What can the GPIO tolerate on a K20-100 running on 1.8V? Customer wants to have 3.3V GPIO.

[Larry5335]

When a K20-100 is running on 1.8 or 2.5 volts VDD, what is the maximum voltage the IO will tolerate?

[egoodii]

Pins in GPIO mode are spec'ed to accept -0.3 to 5.5V, irrespective of Vdd (Vdio in Table 4.4 of datasheet).  That being said, you may have concerns assuring Vil at 0.3*Vdd, or 0.54V for Vdd=1.8V (table 5.2.1).