Schmitt Trigger Calculator
Calculate the upper and lower switching thresholds of an inverting Schmitt trigger built with an op-amp.
V
V
kΩ
kΩ
Upper Threshold (V_TH)
1.091 V
Lower Threshold (V_TL)-1.091 V
Hysteresis Width2.182 V
Upper Threshold (V_TH) vs Positive Saturation
Inverting Schmitt Trigger
Formulas
V_TH = V_sat+ x R1 / (R1 + R2)
V_TL = V_sat- x R1 / (R1 + R2)
Hysteresis = (V_sat+ - V_sat-) x R1 / (R1 + R2)
The ratio R1/(R1+R2) sets the threshold as a fraction of the saturation voltages.
Example Calculation
Op-amp saturates at +/-12 V, R1 = 10k, R2 = 100k.
- 01V_TH = 12 x 10/110 = 1.091 V
- 02V_TL = -12 x 10/110 = -1.091 V
- 03Hysteresis = 24 x 10/110 = 2.182 V
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