I use LM339 to compare two voltage signal. Following is the schematic and the simulation.
I use 10V Vcc, Icc is normal(0.3mA), I want to compare the green(green signal Vpp is 70mV, 20kHz) and blue signal, but LM339 is not working properly. Anyone familiar with LM339 circuit design, or I need another comparator(This circuit is low-voltage and high precision, so is LM339 suitable here?) ?

 

Post you .asc file.

 

Post you .asc file.

I use LTSpice only for two weeks if there's anything missing, please let me know. I will ever be so grateful.

 

I use LTSpice only for two weeks if there's anything missing, please let me know. I will ever be so grateful.

 

The first problem I see is that an LM339 has an open collector output. You have the output connected to different voltage sources through R13 & R17. This cannot possibly be correct. How about telling us what you are trying to do.

 

The first problem I see is that an LM339 has an open collector output. You have the output connected to different voltage sources through R13 & R17. This cannot possibly be correct. How about telling us what you are trying to do.

I replace R17 with a small capacitor and shunt to ground, it does not seem to be correct either. What should be the typical circuit for LM339 comparing two voltage sources?

 

The first problem I see is that an LM339 has an open collector output. You have the output connected to different voltage sources through R13 & R17. This cannot possibly be correct. How about telling us what you are trying to do.

Thank you, I try really small response time, now it seems to be correct.

 

The first problem I see is that an LM339 has an open collector output. You have the output connected to different voltage sources through R13 & R17. This cannot possibly be correct. How about telling us what you are trying to do.

But it is correct.
R17 provides positive feedback for hysteresis.

 

But it is correct.
R17 provides positive feedback for hysteresis.

I got what I want, I change the R17 into a 2nF capacitor and shunt to ground. It works now.