SLUSE22C February   2020  – September 2025 BQ27Z561-R2

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Supply Current
    6. 5.6  Internal 1.8V LDO (REG18)
    7. 5.7  I/O (PULS, INT)
    8. 5.8  Chip Enable (CE)
    9. 5.9  Internal Temperature Sensor
    10. 5.10 NTC Thermistor Measurement Support
    11. 5.11 Coulomb Counter (CC)
    12. 5.12 Analog Digital Converter (ADC)
    13. 5.13 Internal Oscillator Specifications
    14. 5.14 Voltage Reference1 (REF1)
    15. 5.15 Voltage Reference2 (REF2)
    16. 5.16 Flash Memory
    17. 5.17 I2C I/O
    18. 5.18 I2C Timing — 100kHz
    19. 5.19 I2C Timing — 400kHz
    20. 5.20 HDQ Timing
    21. 5.21 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  BQ27Z561-R2 Processor
      2. 6.3.2  Battery Parameter Measurements
        1. 6.3.2.1 Coulomb Counter (CC)
        2. 6.3.2.2 CC Digital Filter
        3. 6.3.2.3 ADC Multiplexer
        4. 6.3.2.4 Analog-to-Digital Converter (ADC)
        5. 6.3.2.5 Internal Temperature Sensor
        6. 6.3.2.6 External Temperature Sensor Support
      3. 6.3.3  Power Supply Control
      4. 6.3.4  Bus Communication Interface
      5. 6.3.5  Low Frequency Oscillator
      6. 6.3.6  High Frequency Oscillator
      7. 6.3.7  1.8V Low Dropout Regulator
      8. 6.3.8  Internal Voltage References
      9. 6.3.9  Gas Gauging
      10. 6.3.10 Charge Control Features
      11. 6.3.11 Authentication
    4. 6.4 Device Functional Modes
      1. 6.4.1 Lifetime Logging Features
      2. 6.4.2 Configuration
        1. 6.4.2.1 Coulomb Counting
        2. 6.4.2.2 Cell Voltage Measurements
        3. 6.4.2.3 Auto Calibration
        4. 6.4.2.4 Temperature Measurements
  8. 7 Applications and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Design Requirements (Default)
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Changing Design Parameters
      3. 7.2.3 Calibration Process
      4. 7.2.4 Gauging Data Updates
        1. 7.2.4.1 Application Curve
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.4.2.1 Coulomb Counting

The device uses an integrating delta-sigma analog-to-digital converter (ADC) for current measurement. The ADC measures charge and 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 –100mV to 100mV, with a positive value when V(SRP) – V(SRN), indicating charge current and a negative value indicating discharge current.

The current measurement is performed by measuring the voltage drop across the external sense resistor, which can be as low as 1mΩ, and the polarity of the differential voltage determines if the cell is in the CHARGE or DISCHARGE mode.