Schmitt Trigger Inputs

Why don’t we have a single value as shown in the illustration below?

This single value cannot lead to lot of misinterpretations



There is a problem with how we define 2.5 (is it 2.49999-2.50001 or something else). To reduce wrong interpretation we have two threshold values, one for low to high transition and one for high to low transition (Shown in below diagram).

Ex: if voltage is rising from zero, and now at 1.5 it is taken, as ‘low’ to get to high it have to pass 2.5

This type of logic gates are called as “Schmitt trigger” input gates. With this we can overcome above problem