BQ27425-G2A shunt resistor

Hi, Hartl-san,

It is an additional question.
The shunt resistor inside BQ27425-G2A will be corrected by the automatic calibration?
Or whether it should be corrected by supplying a current from the outside?

Thanks, Masami M.

My original response was for another part - please disregard the suggestion to calibrate the current gain.

The automatic calibration will not calibrate the current gain. It calibrates the internal offset.

The bq27425 sense resistor, current gain is calibrated in the factory. I'll update this thread with additional data as soon as possible.

Hi, Hartl-san,

Thank you for your support.
I will wait your update.

Thanks, Masami M.

The absolute value of the internal sense resistor can vary quite a bit (approx. 4mOhm to approx. 8mOhm) but this is compensated by TI during production (CC gain trim) so that the current measurement accuracy does not significantly depend on the absolute resistor value.

From a production and customer point of view, the much more important issue is the quality of the connection to the PCB and therefore the battery/cell. If the reflow process is poor, the impedance of the solder ball connection to the PCB will add an uncontrolled additional (and random) impedance to the effective impedance of the sense resistor, skewing the current measurement results and negatively impacting the accuracy of the gauge.

Hi, Hartl-san,

Thank you for your reply.
Please tell me the criteria for adjusting the internal sense resistor at the time of shipment.
It is OK that converted into a value viewed from the customer side, and add a margin.

Thanks, Masami M.

Hi, Hartl-san,

Is the adjustment standard of the internal resistance not available?
For example, even the LSB level at the full scale is OK.
In addition, please tell me when it is available to check it if time is necessary.

Thanks, Masami M.

The gauge will be calibrated at TI for the actual sense resistor value - you can modify the CC Gain value to account for any inaccuracies but this should not be necessary.

I'm not sure what you mean with adjustment standard? Please clarify. Thank you!

Hi, Hartl-san,

The customer wants to know for differences between current value and real electric current level that a device read.
Specifically, they want the value to know the range with the variation of the device.
Are there the data to be able to show?

Thanks, Masami M.