SLVSIU4 April   2026 BQ27Z846

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configurations 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  Supply Current
    5. 5.5  1.8V LDO Regulator (REG18)
    6. 5.6  Low Frequency Oscillator (LFO)
    7. 5.7  High Frequency Oscillator (HFO)
    8. 5.8  PACK Clamp (PACK_CLAMP)
    9. 5.9  Analog-to-Digital Converter (VADC)
    10. 5.10 Coulomb Counter (CCADC)
    11. 5.11 Coulomb Counter Digital Filter (CC1)
    12. 5.12 Current Measurement Digital Filter (CC2)
    13. 5.13 Wake-up Comparator (I-WAKE)
    14. 5.14 Internal Temperature Sensor (INT_TEMP)
    15. 5.15 Thermistor Measurement Support
    16. 5.16 Hardware-based Protection (SCOMP) Thresholds (OVP, UVP, OCC, OCD, SCD)
    17. 5.17 Hardware-based Protections (SCOMP) Timing (OVP, UVP, OCC, OCD, SCD)
    18. 5.18 CHG, DSG NFET Drivers
    19. 5.19 Zero-volt Charging (ZVCHG)
    20. 5.20 General Purpose Input-Outputs (INT)
    21. 5.21 I2C Interface I/O (SDA, SCL)
    22. 5.22 I2C Interface Timing
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  BQ27Z855 Processor
      2. 6.3.2  Battery Parameter Measurements
        1. 6.3.2.1 Analog-to-Digital Converter (VADC)
        2. 6.3.2.2 VADC Multiplexer
        3. 6.3.2.3 Coulomb Counter (CCADC) and Digital Filter (CC1)
        4. 6.3.2.4 Internal Temperature Sensor (INT_TEMP)
        5. 6.3.2.5 External Temperature Sensor Support
      3. 6.3.3  Power Supply Control
      4. 6.3.4  ENAB Pin
      5. 6.3.5  I2C Bus Communication Interface
      6. 6.3.6  Low Frequency Oscillator (LFO)
      7. 6.3.7  High Frequency Oscillator (HFO)
      8. 6.3.8  Real Time Clock (RTC)
      9. 6.3.9  1.8V Low Dropout Regulator (REG18)
      10. 6.3.10 FET Drivers (CHG, DSG)
        1. 6.3.10.1 Charge (CHG) FET Driver
        2. 6.3.10.2 Discharge (DSG) FET Driver
      11. 6.3.11 Zero-volt Charging (ZVCHG)
      12. 6.3.12 Integrated Protections
        1. 6.3.12.1 Hardware-based Protections
          1. 6.3.12.1.1 Overvoltage Protection (OVP)
          2. 6.3.12.1.2 Undervoltage Protection (UVP)
          3. 6.3.12.1.3 Overcurrent in Charge Protection (OCC)
          4. 6.3.12.1.4 Overcurrent in Discharge Protection (OCD)
          5. 6.3.12.1.5 Short Circuit Current in Discharge Protection (SCD)
          6. 6.3.12.1.6 Wake-up Comparator (I-WAKE)
        2. 6.3.12.2 Firmware-based Protections
          1. 6.3.12.2.1 Primary Level Protection Features
          2. 6.3.12.2.2 Permanent Failure Protection Features
      13. 6.3.13 Gas Gauging
      14. 6.3.14 Advanced Battery Algorithms
        1. 6.3.14.1 Si-anode Chemistry Support
        2. 6.3.14.2 Internal Short Indication (ISI)
        3. 6.3.14.3 Battery Swelling Detection (BSD)
      15. 6.3.15 Charge Control Features
      16. 6.3.16 Lifetime Data Logging Features
      17. 6.3.17 Authentication
        1. 6.3.17.1 ECC ECDSA Authentication
        2. 6.3.17.2 SHA-256 Authentication
      18. 6.3.18 Over the Air (OTA) Field Updater
      19. 6.3.19 Configuration
        1. 6.3.19.1 Cell Voltage Measurements
        2. 6.3.19.2 Coulomb Counting
        3. 6.3.19.3 Temperature Measurements
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application Schematics
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 High-Current Path
          1. 7.2.2.1.1 Protection FETs
          2. 7.2.2.1.2 Battery Cell Connections
          3. 7.2.2.1.3 Sense Resistor
          4. 7.2.2.1.4 ESD Mitigation
        2. 7.2.2.2 Gas Gauge Circuit
          1. 7.2.2.2.1 Cell Voltage Measurement Interface
          2. 7.2.2.2.2 Coulomb Counter Interface
          3. 7.2.2.2.3 Temperature Measurement
          4. 7.2.2.2.4 1.8V Low Dropout Regulator (REG18)
          5. 7.2.2.2.5 I2C Communication (SDA, SCL)
          6. 7.2.2.2.6 Interrupt to Host Interface (INT)
        3. 7.2.2.3 Co-design with BQ27Z746 and BQ27Z758
          1. 7.2.2.3.1 Footprint Compatibility and Equivalent Pins
          2. 7.2.2.3.2 Co-layout Example
    3. 7.3 Power Supply Recommendations
  9. 8 Layout
    1. 8.1 Layout Guidelines
  10. 9 Device and Documentation Support
    1. 9.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1.     PACKAGE OPTION ADDENDUM
    2. 11.1 Tape and Reel Information
    3. 11.2 Mechanical Data

6.3.14.1 Si-anode Chemistry Support

Li-ion batteries with silicon-based anodes offer unique advantages compared to Li-ion batteries with graphite-based anodes. The primary advantage is that Li-ion cells with Si-anodes tend to have a higher energy density than Li-ion cells with graphite anodes. However, the silicon degrades faster than graphite in the anode of Li-ion cells causing the Si-anode cell's open circuit voltage (OCV) curve to shift over time with cell aging. This OCV curve shift is especially prevalent in batteries containing a small amount of silicon (up to 20%).

Through device firmware, the BQ27Z846 device enables support for gauging Si-anode cells accurately on both small and dominant silicon type batteries by tracking the OCV curve shift using the predictive modeling of the Dynamic Z-Track™ technology.