BQ2980: BQ2980 + BQ27510 shunt connection

Roman Isaikin

Part Number: BQ2980
Other Parts Discussed in Thread: BQ27510

Hello!

While developing BMS for 1S cell using bq2980+bq27510+mcu I've noticed that bq2980 measures shunt voltage the opposite way compared to bq27510 and that I actually need 2 shunts (1mR for protection and 10mR for gauge). So I'm wondering if the schematic below will work or not?

P.S. Cell is not removable.

over 5 years ago

0 Onyx Ahiakwo over 5 years ago

TI__Guru* 76230 points

Hi Roman
i do not believe i agree with the way you have the schematic set up. The battery positive terminals should be connected to both vdd of the bq2980 and bq27510. Vdd should not be connected via the fets like you have now.

Also i don't see the reason for having two sense resistors. I believe you can have just one sense

thanks
Onyx

0 Roman Isaikin over 5 years ago in reply to Onyx Ahiakwo

Intellectual 270 points

Oh, I see, vdd connection is not an obvious one...

So, the idea to connect CS of bq2980 to 10mR shunt through resistive divider should work?

0 Onyx Ahiakwo over 5 years ago in reply to Roman Isaikin

TI__Guru* 76230 points

I am missing what is your reasoning with using the resistor divider network. That will affect the gauges current measurement as well.

0 Roman Isaikin over 5 years ago in reply to Onyx Ahiakwo

Intellectual 270 points

bq2980 needs 1mR shunt so that SCD would trip at 8A, but if I understand correctly, gauge needs 10mR shunt to be more precise at low currents?

0 Onyx Ahiakwo over 5 years ago in reply to Roman Isaikin

TI__Guru* 76230 points

hi
Place the 1m in series with the 10m and have the 1m have its node connected to cs and vss of the bq28980. Then have those of the 10mohm of the gauge connected between srn and srp

thanks
Onyx

0 Roman Isaikin over 5 years ago in reply to Onyx Ahiakwo

Intellectual 270 points

Thank you very much for your help!

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BQ2980: BQ2980 + BQ27510 shunt connection