In the KL03 datasheet is stated that all I/O pins are NOT diode clamped to V_DD. And V_IO (max) is V_DD + 0.3V.
So I assume that the inputs are NOT 5V-tolerant. I have to use a voltage divider. Is that right?
All I/O pins are internally clamped to VSS through a ESD protection diode. There is no diode connection to VDD.