Hysteresis in Digital or Analog Devices or IC's

Hysteresis the word it self explain the meaning!!!Hysteresis means the lagging of an effect behind its cause!!.If you are familiar with the digital design,you would definitely gone through the data sheets of Digital ICs with some Input hysteresis values say 200mV.What it does actually meant for? the answer is simple

Let say you detect a Low to high transition at 1.8V(Vref).A 200 mV Hysteresis would mean that your device will detect the Low to high transition at 1.9V and the High to low transition locked at 1.7V.This voltage lag between activating and deactivating the device is known as the Hysteresis of the system.Hysteresis is ensure to avoid several noise transitions would cause the H-L and L-H transitions of the device.So a 200mV Hysteresis means that noise levels lesser than 200mV wont give any disturbance to the Vref of your system..