Original question:
Hi,
If VCC=3V, when input voltage from low up to 1.48V, then the output will be high voltage as VCC. And input voltage down below 1.2V, then output become low level. The input voltage hysteresis we should check is VT+ and VT-? What's the deltaVt hysteresis mean?
Delta Vt is the difference between the positive and negative going threshold.
It is this delta Vt which gives the noise immunity for the schmitt trigger devices.
You can refer to the app note for more information on it.
