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comparator hysteresis - help needed

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Jevon

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comparator hysteresis

Hi all,

I've got a comparator comparing the value from an open collector sensor (pull up to 5V through a 10k) and 2.5V (set up through pot. divider... 2 x 10k res.). I'm getting kick back noise which is a problem because they comparator output (open collector pulled up with a 10k as well) is fed to a counter.
Because of the way the inputs are set up, I'm not sure how to set up feed back to sort out the noise problem.
Suggestions would be great.

Thanks
 

Re: comparator hysteresis

Hi,

If you can make the comparator sluggish by reducing bias current, it can solve the problem. Basically it is slowing down the comparator output.
In case you need very fast response from the comparator, then adding hysteresis can solve the problem.
 

    J

    Jevon

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Re: comparator hysteresis

Jevon said:
Because of the way the inputs are set up, I'm not sure how to set up feed back to sort out the noise problem.
Click to expand...
Both your comparator inputs own an input resistance of 5kΩ. So if you want e.g. a hysteresis of 1% (means 50mV in a 5V system), you use a feedback resistor (to the positive input) of (input_resistance / hysteresis_percentage) value, i.e. 500kΩ in your case.
 

    J

    Jevon

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