JAJSFE4B May 2015 – May 2018
PRODUCTION DATA.
The bq27546-G1 fuel gauge measures the cell voltage, temperature, and current to determine battery SOC based on the Impedance Track algorithm. (For more information, refer to the Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm Application Report [SLUA450].) The device monitors charge and discharge activity by sensing the voltage across a small-value resistor (5-mΩ to 20-mΩ typical) between the SRP and SRN pins and in series with the cell. By integrating the charge passing through the battery, the battery SOC is adjusted during battery charge or discharge.
The total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. When an application load is applied, the impedance of the cell is measured by comparing the OCV obtained from a predefined function for present SOC with the measured voltage under load. Measurements of OCV and charge integration determine chemical state of charge and chemical capacity (Qmax). The initial Qmax values are taken from a cell manufacturer's data sheet multiplied by the number of parallel cells. It is also used for the value in Design Capacity. The fuel gauge acquires and updates the battery-impedance profile during normal battery usage. It uses this profile, along with SOC and the Qmax value, to determine FullChargeCapacity() and StateOfCharge(), specifically for the present load and temperature. FullChargeCapacity() is reported as capacity available from a fully charged battery under the present load and temperature until Voltage() reaches the Terminate Voltage. NominalAvailableCapacity() and FullAvailableCapacity() are the uncompensated (no or light load) versions of RemainingCapacity() and FullChargeCapacity(), respectively.