Kria SOMs support all I/O standards supported by the respective bank that a signal is connected to with the exception of I/O standards that require a reference voltage (VREF). For more information, refer to the UltraScale Architecture SelectIO Resources User Guide (UG571).
During power-up and configuration, internal pull-up resistors are disabled and each SelectIO™ pin is set to 3-state.
The K26 SOM is built with the XCK26-SFVC784-2LV device; which has a -2 speed grade and is an LV device (operates at VCCINT = 0.72V).
The K24 SOM is built with the XCK24-UBVA530-2LV device; which has a -2 speed grade and is an LV device (operates at VCCINT = 0.72V).
Consult the corresponding I/O speed tables in the Zynq UltraScale+ MPSoC Data Sheet: DC and AC Switching Characteristics (DS925) for the switching characteristics. I-grade SOM devices can differ from the standard MPSoC. Exceptions overriding the standard definition are listed in each SOM data sheet. Refer to the K26I SOM I-grade specification in the Kria K26 SOM Data Sheet (DS987) or the K24I SOM industrial grade specification in the Kria K24 SOM Data Sheet (DS985).