SLUUC54C February 2020 – March 2024 BQ27Z558 , BQ27Z561 , BQ27Z561-R2
The integrating delta-sigma ADC in the gauge measures the charge/discharge flow of the battery by measuring the voltage drop across a small-value sense resistor between the SRP and SRN pins. The 16-bit integrating ADC measures bipolar signals from –0.10 V to 0.10 V with 3.74-µV resolution. The gauge reports charge activity when VSR = V(SRP) – V(SRN) is positive, and discharge activity when VSR = V(SRP) – V(SRN) is negative. This data is scaled and translated into mA using CC Gain and reported through Current(). The gauge uses this information for gauging and lifetime data logging functions. In NORMAL and SLEEP modes, the gauge continuously monitors the measured current and integrates the digital signal over time using an internal coulomb counter, which is also used for gauging.
In addition, the integrating ADC is sampled during voltage measurements and converted to mA in the same manner. This data is used for gauging (but not coulomb counting) and reported through Cell 1 Current in DAStatus1().
The data reported through Current() can also have a deadband applied to it. This removes any noise or offset that has not been calibrated out from being reported as real current or from being accumulated by the coulomb counter in DOD0 Passed Q. This deadband value is programmed in Deadband.