BQ77915: Design formula required for bq77915 controller

Hello Udhaya,

All of these essentially boil down to Ohm's law, V = I*R.

For the balancing resistor Vcell/(Rbal + Rin + Rin), as mentioned in the image you shareed:

• According to the datasheet, 33-Ohm input resistors would give ~50-mA of internal current @ 4.2-V.
  • 4.2-V/50-mA = 84-Ohms.
  • So Rin = ~18-Ohms if we solve for Rin in the original equation.

For the sense resistor:

• If you have a protection that will trigger at 30-A, and you have a threshold of 60-mV, the sense resistor may be Rsns = Vsns / Isns = 60-mV / 30-A = 2-mOhms.
• You then must take into account what the datasheet gives and its examples. But that's the basic formula.

For the gate resistor, I would recommend to use what is recommended in the datasheet/EVM.

Best Regards,

Luis Hernandez Salomon

Dear Luis, Thanks for your support.