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Rc and Cc of the BQ76930

user4574471
Prodigy 90 points
Other Parts Discussed in Thread: BQ76930

How to choose Rc and Cc of the  BQ76930 ?

  • 0
    TI__Expert 6085 points

    R can be sized to to dissipate the extra power loss seen during the cell balancing.  Also for bq76930 , the input filters -resistor Rc  to keep the balance current small. Cc cap for improved measurement.

    Rc is typically ( 1K)  selected based on the balancing current, [ 2 *4.25/ 2 *1K ] =4.25mA. balancing current is low..but may be acceptable for expected balancing windows and overnight charging.

    Also  the max power per balancing resistor  (4.25mA*4.25mA) *1k = 18mW

    RC filter for high frequency filtering,  LPF = 1 / ( 2*pi* 1K *0.1u) =1.6KHz

  • 0 in reply to Vish Nadarajah
    Prodigy 90 points
    Thanks! If the external balance circuit, can reduce the Rc to improve the balance of current?
  • 0 in reply to user4574471
    TI__Expert 6085 points

    yes.  A higher Balance current can be achieved by reducing the Rc.  The power filter ( filter for the VCnX pins)

     also must be reduced.  The EVM schematics on the d/s use larger input Rc to reduce transient voltages to the inputs.