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BQ76940EVM: BQ76940EVM Cell Balancing

Part Number: BQ76940EVM
Other Parts Discussed in Thread: BQ76940

We observed adjacent cells are switched on (for short duration) during cell balancing test.

We have to add a N-mosfet in between in order to get the cell balancing to work with our existing PCB.

Please refer below for schematics of 15 cells balancing circuit.

Is there a way to get rid of this issue or this is normal for BQ76940?

  • Hi Brandon,

    I'm not able to get access to your schematic, perhaps you can post a larger clip of the topology in question.  In general the input filter capacitors for BQ76940 are connected in sequence so a change on one will influence the others.  You can reduce the effect with smaller time constant, for the BQ76940 that should be with smaller capacitors. There will still be an impulse, you might make the FET less responsive to it with a small capacitor across the gate to source. If you like simulation you might values in a simulator such as or