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BQ76920: Correct chip for the task?

Jonathan Reinfelds
Prodigy 60 points
Part Number: BQ76920

Beginner looking for some guidance on chip selection.

I have a 4S LiFePO4 battery that I wish to read the voltages across the entire battery as well as each cell.  I do not require any additional features related to charging, balancing, temperature, etc.  Just the voltages, so that I can read them into a microcontroller for output onto a display.  

I did some research and found various solutions ranging from voltage dividers to opto-isolators, but none seemed to be ideal - they all either lacked in accuracy and/or safety.  I then stumbled across the BQ76920 chip - but I am wondering if this chip is a bit of overkill for the application.  Is this the right chip?  Is there another chip/process that would be "better"?     I am hoping for an accuracy of within 0.05V 

Thank you all in advance!

  • 0
    TI__Expert 6085 points
    The bq769x0 may be an overkill; Since these family of IC have monitoring and protection integrated. If just for monitoring cell voltages, all you need ( depending on the power consumption constraints, a series R ( with tight tolerance) network to measure the individual cell voltages and stack voltage into the uC with the ADC channels. Depending on the calibration and ADC sampling techniques, you should be able to achieve the accuracy of 50mV!

    good luck
  • 0 in reply to Vish Nadarajah
    Prodigy 60 points

    Thanks Vish.  Sorry for my ignorance, but I am unfamiliar with series R network.  Do you mean a series of resistors (essentially a voltage divider)? 

    If using ADC channels, as I am using Arduino as the microcontroller, I am guessing an external ADC would be better to get more accurate results.