Hi JiHoo
The input voltage of the analog-to-digital converter is specified in the Kinetis K64F Sub-Family DataSheet. It's possible to find this characteristic in chapter 3.6.1 on the table 30 of this document, as it is shown below.
The Input voltage (VADIN) accepts values between the ADC reference voltage low and high (VREFL and VREFH). This reference voltages depend on the value of the ground voltage (VSSA) and the supply voltage (VDDA).
Then, the ADC input voltage range is 0 ±100mV to 3.6V±100mV(depending on the supply voltage).
Please let me know if you need any more information.
Jose
