If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
GNDX GND for the Hibernation oscillator. When using a crystal clock source, this pin should only be connected to the crystal load capacitors to improve oscillator immunity to system noise. When using an external oscillator, this pin should be connected to GND.
VDDA The positive supply for the analog circuits (ADC, Analog Comparators, etc.). These are separated from VDD to minimize the electrical noise contained on VDD from affecting the analog functions. VDDA pins must be supplied with a voltage that meets the specification in Table 24-5 on page 1389, regardless of system implementation.
VDDC Positive supply for most of the logic function, including the processor core and most peripherals. The voltage on this pin is 1.2 V and is supplied by the on-chip LDO. The VDDC pins should only be connected to each other and an external capacitor as specified in Table 24-12 on page 1401.
