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Needing help choosing a precision comparator
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Pentoad:
Hello all,

I am trying to design a module which is to be placed upon each cell in a lithium ion battery bank. The module is to dissipate excess energy to maintain the cell voltage at 4.1v. It needs to be accurate to within a millivolt. For the comparator, I was thinking of using an LM339 which has a typical input offset voltage of 1mv but this can be as high as 5 or 9mv. My voltage reference will be a TL431A.

The bulb in the diagram will be a high power resistor. Will this setup give the accuracy I'm looking for? If so, I will use a 4 channel comparator and the other inputs will be used as over voltage and under voltage warnings which will be optocoupled to an external management unit.

jhpadjustable:
Any particular reason you aren't using a proper battery protection IC? Ablic (formerly Seiko Semiconductor) offers a wide variety of battery pack functions, some with balancing functionality built in.
Marco:
The TL431 is a three pin device with an integrated opamp, you don't need a comparator just an external transistor.
Pentoad:

--- Quote from: jhpadjustable on October 06, 2019, 02:17:50 am ---Any particular reason you aren't using a proper battery protection IC? Ablic (formerly Seiko Semiconductor) offers a wide variety of battery pack functions, some with balancing functionality built in.

--- End quote ---

Just because I want to make something simple and accurate for a college project with full voltage adjustability.
Pentoad:
So I found a circuit here which would accomplish that without using an external comparator. Where about could I place a potentiometer to adjust the voltage it triggers at to 4.1?

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