8.3.4 Bus Communication Interface

The BQ27Z561-R2 device has an I2C bus communication interface. Alternatively, the BQ27Z561-R2 can be

configured to communicate through the HDQ pin (shared with SDA).

Note

Once the device is switched to the HDQ protocol, it is not reversible.

8.3.5 Low Frequency Oscillator

The BQ27Z561-R2 device includes a low frequency oscillator (LFO) running at 65.536 kHz.

8.3.6 High Frequency Oscillator

The BQ27Z561-R2 includes a high frequency oscillator (HFO) running at 16.78 MHz. It is frequency locked to

the LFO output and scaled down to 8.388 MHz with a 50% duty cycle.

8.3.7 1.8-V Low Dropout Regulator

The BQ27Z561-R2 device contains an integrated capacitor-less 1.8-V LDO (REG18) that provides regulated

supply voltage for the device CPU and internal digital logic.

8.3.8 Internal Voltage References

The BQ27Z561-R2 device provides two internal voltage references. REF1 is used by REG18, oscillators, and

CC. REF2 is used by the ADC.

8.3.9 Gas Gauging

This device uses the Impedance Track™ technology to measure and determine the available charge in battery

cells. See the Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm Application

Report for further details.

8.3.10 Charge Control Features

This device supports charge control features, such as:

• Reports charging voltage and charging current based on the active temperature range—JEITA temperature

ranges T1, T2, T3, T4, T5, and T6

• Provides more complex charging profiles, including sub-ranges within a standard temperature range

• Reports the appropriate charging current required for constant current charging, and the appropriate charging

voltage needed for constant voltage charging to a smart charger, using the bus communication interface

• Compensates the charging profile based on the value of RelativeStateOfCharge()

• Selects the chemical state-of-charge of each battery cell using the Impedance Track method

• Reports charging faults and indicates charge status via charge and discharge alarms

8.3.11 Authentication

This device supports security with the following features, which can be enabled if desired:

• Authentication by the host using the SHA-256 method

• The gas gauge requires SHA-256 authentication before the device can be unsealed or allow full access.

8.4 Device Functional Modes

This device supports five modes, but the current consumption varies, based on firmware control of certain

functions and modes of operation:

• NORMAL mode: In this mode, the device performs measurements, calculations, protections, and data

updates in 250-ms intervals. Between these intervals, the device is operating in a reduced power stage

to minimize total average current consumption.

• SLEEP mode: In this mode, the device performs measurements, calculations, and data updates in adjustable

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

average current consumption.

www.ti.com

BQ27Z561-R2

SLUSE22B – FEBRUARY 2020 – REVISED NOVEMBER 2022

Copyright © 2022 Texas Instruments Incorporated

Submit Document Feedback

13

Product Folder Links: BQ27Z561-R2