Trying to see where this data goes… 
Seems like we have to read from the ADC12_IN16 channel…
More information at page 226:
In the core-common code there’s a function to set the bit TSVREFE!
I can’t go any further than this and sure @mohit can help with all the information gathered above.
Looking at the analogread code and i believe some code there can be used to read this particular channel…