• To set the Cell Low Voltage or clear the Cell Low Voltage, use Settings: Configuration: Init Voltage Low

Set or Clear. This is used to set the cell voltage level that will set (clear) the [VOLT_LO] bit in the Interrupt

Status register.

• To enable the internal temperature and the external temperature sensors: Set Settings:Configuration:

Temperature Enable: Bit 0 (TSInt) = 1 for the internal sensor; set Bit 1 (TS1) = 1 for the external sensor.

9.2.3 Calibration Process

The calibration of current, voltage, and temperature readings is accessible by writing 0xF081 or 0xF082 to

ManufacturerAccess(). A detailed procedure is included in the BQ27Z561-R2 Technical Reference Manual

in the Calibration section. The description allows for calibration of cell voltage measurement offset, battery

voltage, current calibration, coulomb counter offset, PCB offset, CC gain and capacity gain, and temperature

measurement for both internal and external sensors.

9.2.4 Gauging Data Updates

When a battery pack enabled with the BQ27Z561-R2 gas gauge is cycled, the value of FullChargeCapacity()

updates several times, including the onset of charge or discharge, charge termination, temperature delta,

resistance updates during discharge, and relaxation. Figure 9-3 shows actual battery voltage, load current,

and FullChargeCapacity() when some of those updates occur during a single application cycle.

Update points from the plot include:

• Charge termination at 7900 s

• Relaxation at 9900 s

• Resistance update at 11500 s

9.2.4.1 Application Curve

Figure 9-3. Full Charge Capacity Tracking (X-Axis Is Seconds)

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BQ27Z561-R2

SLUSE22B – FEBRUARY 2020 – REVISED NOVEMBER 2022

Copyright © 2022 Texas Instruments Incorporated

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