Download The Schmitt Trigger

The Schmitt Trigger
The Schmitt trigger is
a comparatorapplication which switches
the output negative when the input
passes upward through a positive
reference voltage. It then uses negative
feedback to prevent switching back to
the other state until the input passes
through a lower threshold voltage, thus
stabilizing the switching against rapid
triggering by noise as it passes the
trigger point.
Comparator Applications
Schmitt Trigger Action
The Schmitt trigger action uses a comparator to
produce stable level-crossing switches in
contrast to the action of a straight reference
comparison.
Comparator Applications
For circuit parameters:
=
V
=
=
=
the trigger voltage will be
=
V
and it will hold until the signal drops to
=
V
1
The Schmitt Trigger
Schmitt trigger action is a double
thresholdcomparator process. The current
equation at A gives:
where
This dependence upon the output voltage
gives the dual threshold. The two output states
give the thresholds shown at right.
2