13.11.6.5.7 Hysteresis
A hysteresis on the trigger threshold of a BOD will reduce the sensitivity to ripples on the monitored voltage: instead of switching RESET at each crossing of VBOD, the thresholds for switching RESET on and off are separated (VBOD- and VBOD+, respectively).
Enabling the BOD33 hysteresis by writing the Hysteresis bit in the BOD33 register (BOD33.HYST) to '1' will add hysteresis to the BOD33 threshold level.
The hysteresis functionality can be used in both Continuous and Sampling Mode.