SLUSE86A April   2022  – April 2024 BQ76922

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information BQ76922
    5. 6.5  Supply Current
    6. 6.6  Digital I/O
    7. 6.7  LD Pin
    8. 6.8  Precharge (PCHG) and Predischarge (PDSG) FET Drive
    9. 6.9  FUSE Pin Functionality
    10. 6.10 REG18 LDO
    11. 6.11 REG0 Pre-regulator
    12. 6.12 REG1 LDO
    13. 6.13 Voltage References
    14. 6.14 Coulomb Counter
    15. 6.15 Coulomb Counter Digital Filter (CC1)
    16. 6.16 Current Measurement Digital Filter (CC2)
    17. 6.17 Current Wake Detector
    18. 6.18 Analog-to-Digital Converter
    19. 6.19 Cell Balancing
    20. 6.20 Cell Open Wire Detector
    21. 6.21 Internal Temperature Sensor
    22. 6.22 Thermistor Measurement
    23. 6.23 Internal Oscillators
    24. 6.24 High-side NFET Drivers
    25. 6.25 Comparator-Based Protection Subsystem
    26. 6.26 Timing Requirements – I2C Interface, 100kHz Mode
    27. 6.27 Timing Requirements – I2C Interface, 400kHz Mode
    28. 6.28 Timing Requirements – HDQ Interface
    29. 6.29 Interface Timing Diagrams
    30. 6.30 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1  Overview
    2. 7.2  Functional Block Diagram
    3. 7.3  Diagnostics
    4. 7.4  Device Configuration
      1. 7.4.1 Commands and Subcommands
      2. 7.4.2 Configuration Using OTP or Registers
      3. 7.4.3 Device Security
      4. 7.4.4 Scratchpad Memory
    5. 7.5  Measurement Subsystem
      1. 7.5.1  Voltage Measurement
        1. 7.5.1.1 Voltage Measurement Schedule
        2. 7.5.1.2 Using VC Pins for Cells Versus Interconnect
        3. 7.5.1.3 Cell 1 Voltage Validation During SLEEP Mode
      2. 7.5.2  General Purpose ADCIN Functionality
      3. 7.5.3  Coulomb Counter and Digital Filters
      4. 7.5.4  Synchronized Voltage and Current Measurement
      5. 7.5.5  Internal Temperature Measurement
      6. 7.5.6  Thermistor Temperature Measurement
      7. 7.5.7  Factory Trim of Voltage ADC
      8. 7.5.8  Voltage Calibration (ADC Measurements)
      9. 7.5.9  Voltage Calibration (COV and CUV Protections)
      10. 7.5.10 Current Calibration
      11. 7.5.11 Temperature Calibration
    6. 7.6  Primary and Secondary Protection Subsystems
      1. 7.6.1 Protections Overview
      2. 7.6.2 Primary Protections
      3. 7.6.3 Secondary Protections
      4. 7.6.4 High-Side NFET Drivers
      5. 7.6.5 Protection FETs Configuration and Control
        1. 7.6.5.1 FET Configuration
        2. 7.6.5.2 PRECHARGE and PREDISCHARGE Modes
      6. 7.6.6 Load Detect Functionality
    7. 7.7  Device Hardware Features
      1. 7.7.1  Voltage References
      2. 7.7.2  ADC Multiplexer
      3. 7.7.3  LDOs
        1. 7.7.3.1 Preregulator Control
        2. 7.7.3.2 REG1 LDO Control
      4. 7.7.4  Standalone Versus Host Interface
      5. 7.7.5  Multifunction Pin Controls
      6. 7.7.6  RST_SHUT Pin Operation
      7. 7.7.7  CFETOFF, DFETOFF, and BOTHOFF Pin Functionality
      8. 7.7.8  ALERT Pin Operation
      9. 7.7.9  Fuse Drive
      10. 7.7.10 Cell Open Wire
      11. 7.7.11 Low Frequency Oscillator
      12. 7.7.12 High Frequency Oscillator
    8. 7.8  Device Functional Modes
      1. 7.8.1 Overview
      2. 7.8.2 NORMAL Mode
      3. 7.8.3 SLEEP Mode
      4. 7.8.4 DEEPSLEEP Mode
      5. 7.8.5 SHUTDOWN Mode
      6. 7.8.6 CONFIG_UPDATE Mode
    9. 7.9  Serial Communications Interface
      1. 7.9.1 Serial Communications Overview
      2. 7.9.2 I2C Communications
      3. 7.9.3 HDQ Communications
    10. 7.10 Cell Balancing
      1. 7.10.1 Cell Balancing Overview
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements (Example)
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Performance Plot
      4. 8.2.4 Calibration Process
    3. 8.3 Random Cell Connection Support
    4. 8.4 Startup Timing
    5. 8.5 FET Driver Turn-Off
    6. 8.6 Unused Pins
  10. 9 Power Supply Requirements
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RSN|32
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.7.10 Cell Open Wire

The BQ76922 device supports detection of a broken connection between a cell in the pack and the cell attachment to the PCB containing BQ76922. Without this check, the voltage at the cell input pin of the BQ76922 device may persist for some time on the board-level capacitor, leading to incorrect voltage readings. The Cell Open Wire detection in the BQ76922 device operates by enabling a small current source from each cell to VSS at programmable intervals. If a cell input pin is floating due to an open wire condition, this current discharges the capacitance, causing the voltage at the pin to slowly drop. This drop in voltage eventually triggers a protection fault on that particular cell and the cell above it. Eventually, the voltage drops low enough to trigger a Permanent Fail on the particular cell and the cell above it.

The Cell Open Wire current is enabled at a periodic interval set by configuration register. The current source is enabled once every interval for a duration of the ADC measurement time (which is 3ms by default). This provides programmability in the average current drawn from approximately 0.65nA to approximately165nA, based on the typical current level of 55µA.

Note: The Cell Open Wire check can create a cell imbalance, so the settings should be selected appropriately.