Hi,
V is the output of the delta-sigma and it needs to be fed back to the input to close the delta-sigma loop.
There are two main reasons to reset a delta-sigma modulator.
1- To lock up the ADC when the internal states get saturated.
2- To serve as a resettable ADC (well-known as incremental ADCs). In the incremental mode, the delta-sigma gets reset every OSR cycle and the ADC starts digitizing the next channel.
It's always nice to have reset signal even though the ADC is not going to be used in an Incremental mode. Otherwise, you need to play with supply voltage to lock up the ADC
!!!
Tnx