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Sense resistor for high current ~200A

Ryszard Brzukala
Prodigy 20 points
Part Number: BQ40Z80 
I want to use the BQ40Z80 only to balance 6 cells and monitor them, bypassing the charge and discharge protection FETs. The external charger will take care of charging. The problem I encountered was too much current for the measuring resistor recommended in the documentation. To reduce power and voltage losses on outpot, it would be advisable to use a resistor of 0.0001ohm or less, is the BQ40Z80 capable of working with such a small measuring resistor? Or can I skip it and still keep the balancing ability?
  • 0
    TI__Guru** 105590 points

    Hello Ryszard,

    It is not recommended to go below 1mOhm for sense resistor on our gauges, it will introduce noise into the CC and can potentially cause gauging issues. I would set the sense resistor as high as possible if under 1mOhm and do system verification to make sure there are no issues since we do not guarantee performance with lower sense resistor values.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points 
    Thank you for your comprehensive answer. In that case, do I have another question, or are you aware of another TI 
    manufacturing system capable of working within these guidelines?
  • 0 in reply to Ryszard Brzukala
    TI__Guru** 105590 points

    Hello Ryszard,

    With a sense resistor this low there will always be some issues with noise. You can use TI gauge parts but you may need to do additional testing to verify the operation is correct. We have some parameters we can adjust to help mitigate any issues relating to low sense resistor value, like the CC deadband which is the current we ignore if it is too low.

    Sincerely,

    Wyatt Keller