Calibration for CC Offset is not possible for Zero Current

Maximilian,

Which device are you using? Can you provide a schematic for your module?

Regards
Tom

Tom,

in order to get zero current detection by using the bq20z65 we found the CC current value (see TRM para. C.13.2.1).

Which influence has the changing of the given value?

Regards
Roland

Roland,

The CC Current value does not affect zero current reporting. It is used to calibrate out errors at high current. You can reduce this value, but if can increase noise and offset errors. The current should report 0 after calibrating the Board Offset and CC Offset. Also, did you calibrate the temperature before calibrating current? An accurate temperature measurement is required to calibrate current accurately.

Regards
Tom

Tom,

the bq20z65 has two thermal couples inputs. You can decide if you are going to use one or both. 

Will both temperature inputs implicate the current calibration?

Regards

Roland

Roland

The device should use the internal temperature sensor for current calibration.

Tom

Tom,

I have the same problem with BQ20855 IC which is a custom design. When i calculate the board offset, appears error message that says the value is beyond threshold and 127 (max. value) is written to Board Offset register of IC. The CC Offset calculation doesn't change the result. Current in SBS screen displays about 7-8mA without any load.

By the way, for reducing temperature on pcb during high current flowing, the pcb dimension is larger than it should be. (85x65x1.6mm)

Note:Bq20855 is derived from Bq2083 IC

please find the attached file that includes schematic.

4848.BQ20855 BMU Schematic.pdf