BQ27426: external shunt resister design

Koji Ikeda

Part Number: BQ27426

Hello support team,

My customer is investigating bq27426. bq27426 recommend 10mOhm shunt resister and the Coulomb Counter input range is +/-25mV, this means that the monitoring load range is +/-2.5A. However, they would like to use higher load current range, like 5A. In this case, they should use R= 25mV / Imax, is their understanding correct?

Thanks,

Koji Ikeda

over 5 years ago

0 Dominik Hartl11 over 5 years ago

TI__Guru 62076 points

You can use a smaller sense resistor. The minimum recommended value is 5mOhm. Going lower will lead to poor accuracy.

0 Koji Ikeda over 5 years ago in reply to Dominik Hartl11

TI__Expert 6325 points

Dominik-san,

Thank you for your support. Could you show how to calculate the resister value? I found another post on E2E and the 25mV on datasheet might be typo. Please clarify the input range.

https://e2e.ti.com/support/power-management/f/196/t/752899?tisearch=e2e-sitesearch&keymatch=BQ27426%20shunt

Thanks,

Koji Ikeda