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Scmitt Trigger Intro

A Schmitt Trigger is a comparator circuit with two threshold voltages, upper (V<sub>UT</sub>) and lower (V<sub>LT</sub>), which provides noise immunity through hysteresis. It switches output states based on these thresholds, making it effective for converting noisy analog signals into clean digital signals. Common applications include debouncing switches, waveform shaping, signal conditioning, and oscillators.

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Rhenne-Ann Orayan
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25 views2 pages

Scmitt Trigger Intro

A Schmitt Trigger is a comparator circuit with two threshold voltages, upper (V<sub>UT</sub>) and lower (V<sub>LT</sub>), which provides noise immunity through hysteresis. It switches output states based on these thresholds, making it effective for converting noisy analog signals into clean digital signals. Common applications include debouncing switches, waveform shaping, signal conditioning, and oscillators.

Uploaded by

Rhenne-Ann Orayan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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⚡ What Is a Schmitt Trigger?

A Schmitt Trigger is a type of comparator circuit with hysteresis. That means it has two
different threshold voltages:

 Upper Threshold Voltage (V<sub>UT</sub>)


 Lower Threshold Voltage (V<sub>LT</sub>)

This dual-threshold behavior helps it filter out noise and prevent false triggering when the
input signal is near the switching point.

🧠 How It Works

 When the input voltage rises above V<sub>UT</sub>, the output switches high.

 The output stays high until the input falls below V<sub>LT</sub>, at which point it
switches low.
 This gap between V<sub>UT</sub> and V<sub>LT</sub> is called hysteresis, and it’s
what gives the Schmitt Trigger its noise immunity.

This behavior is especially useful when dealing with slow or noisy analog signals that need to
be converted into clean digital signals.

🔁 Inverting vs. Non-Inverting

Type Input Location Output Behavior


Inverting Input to inverting terminal Output is opposite of input logic
Non-Inverting Input to non-inverting terminal Output follows input logic with hysteresis

🛠️Common Applications

 Debouncing switches (eliminates chatter)


 Waveform shaping (turns sine or triangle waves into square waves)

 Signal conditioning (cleans up noisy analog signals)


 Oscillators (used in relaxation oscillator circuits)

🧪 Simple Example

Imagine a Schmitt Trigger with:

 V<sub>UT</sub> = 3V
 V<sub>LT</sub> = 1V

If the input slowly rises from 0V:


 Output stays low until input > 3V → then output goes high.
 Output stays high until input drops < 1V → then output goes low.

This prevents the output from flipping back and forth due to small fluctuations between 1V and 3V.

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