how a voltage detector works
In general for anywhere a system has to be activated based on a threshold voltage,
a comparator with a hysteresis is used, where the hysteresis ensures that after
the system gets activated, its de-activation wont be triggered due to noise or
by chance, unless the threshold voltage recovers from the activation threshold
below a certain level.......
This is just to aviod rapid toggling of the system between its activation and
de-activation states......