Question on LM339 Simulation

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mohaad

Joined Jan 12, 2021
2
Hello,

Please refer to the attached images. I got the LM339's LTSpice model from https://github.com/evenator/LTSpice-Libraries/blob/master/sub/LM339.sub
I connected the circuit like that shown on the image and expected the output voltage, Vout, to be 1, a digital signal. However, the output is 17.2mV. I would like to know if this is my mistake or something wrong with the model?
 

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dl324

Joined Mar 30, 2015
12,255
I connected the circuit like that shown on the image and expected the output voltage, Vout, to be 1, a digital signal.
Why are you using a simulator for such a simple circuit? That's kind of like using a calculator to add 2 + 3.
 

Wolframore

Joined Jan 21, 2019
2,192
For single supply situation, If neg is > pos output = 0, if neg < pos it goes high. For a simple comparator when both are equal it can go either way with actual component, hysteresis helps that issue and also mitigates oscillation.

The mV you see is min output voltage at the lower rail.
 
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