Hi John,
MK02FN128VFM10 can operate at the full 100Mhz, because this chip have wide range of operation voltage:1.71v-3.6V, then you can use 1.8V.
About the detail performance implications when running at 1.8V vs.3.3V, unfortunately, we don't have it until now, you can use the 1.8V operation voltage and test it.
Any question, please contact with us.
Wish it helps you!
If you still have question, please contact me!
Have a great day,
Jingjing
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