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BQ27Z561-R1

SLUSDH5 – MARCH 2019

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Copyright © 2019, Texas Instruments Incorporated

Device Functional Modes (continued)

time intervals. Between these intervals, the device is operating in a reduced power stage to minimize total

average current consumption.

•

DEEP SLEEP mode: In this mode, the current is reduced slightly while current and voltage are still measured

periodically, with a user-defined time between reads.

•

OFF mode: The device is completely disabled by pulling CE low. CE disables the internal voltage rail. All non-

volatile memory is unprotected.

8.4.1 Lifetime Logging Features

The device supports data logging of several key parameters for warranty and analysis:

•

Maximum and Minimum Cell Temperature

•

Maximum Current in CHARGE or DISCHARGE Mode

•

Maximum and Minimum Cell Voltages

•

Total Run Time (This data is stored with a resolution of 2 hours.)

•

Time spent different temperature ranges (This data is stored with a resolution of 2 hours.)

8.4.2 Configuration

The device supports accurate data measurements and data logging of several key parameters.

8.4.2.1 Coulomb Counting

The device uses an integrating delta-sigma analog-to-digital converter (ADC) for current measurement. The ADC

measures charge/discharge flow of the battery by measuring the voltage across a very small external sense

resistor. The integrating ADC measures a bipolar signal from a range of –100 mV to 100 mV, with a positive

The current measurement is performed by measuring the voltage drop across the external sense resistor, which

can be as low as 1 mΩ, and the polarity of the differential voltage determines if the cell is in the CHARGE or

DISCHARGE mode.

8.4.2.2 Cell Voltage Measurements

The BQ27Z561-R1 gas gauge measures the cell voltage at 1-s intervals using the ADC. This measured value is

internally scaled for the ADC and is calibrated to reduce any errors due to offsets. This data is also used for

calculating the impedance of the cell for Impedance Track gas gauging.

8.4.2.3 Auto Calibration

The auto-calibration feature helps to cancel any voltage offset across the SRP and SRN pins for accurate

measurement of the cell voltage, charge/discharge current, and thermistor temperature. The auto-calibration is

performed when there is no communication activity for a minimum of 5 s on the bus lines.

8.4.2.4 Temperature Measurements

This device has an internal sensor for on-die temperature measurements, and the ability to support an external

temperature measurement via the external NTC on the TS pin. These two measurements are individually

enabled and configured.

9 Applications and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.