SLUSFC9 December   2023 BQ76972

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 BQ76952
    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 REG2 LDO
    14. 6.14 Voltage References
    15. 6.15 Coulomb Counter
    16. 6.16 Coulomb Counter Digital Filter (CC1)
    17. 6.17 Current Measurement Digital Filter (CC2)
    18. 6.18 Current Wake Detector
    19. 6.19 Analog-to-Digital Converter
    20. 6.20 Cell Voltage Measurement Accuracy
    21. 6.21 Cell Balancing
    22. 6.22 Cell Open Wire Detector
    23. 6.23 Internal Temperature Sensor
    24. 6.24 Thermistor Measurement
    25. 6.25 Internal Oscillators
    26. 6.26 High-side NFET Drivers
    27. 6.27 Comparator-Based Protection Subsystem
    28. 6.28 Timing Requirements - I2C Interface, 100kHz Mode
    29. 6.29 Timing Requirements - I2C Interface, 400kHz Mode
    30. 6.30 Timing Requirements - HDQ Interface
    31. 6.31 Timing Requirements - SPI Interface
    32. 6.32 Interface Timing Diagrams
    33. 6.33 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1  Overview
    2. 7.2  Functional Block Diagram
    3. 7.3  BQ76972 Device Versions
    4. 7.4  Diagnostics
    5. 7.5  Device Configuration
      1. 7.5.1 Commands and Subcommands
      2. 7.5.2 Configuration Using OTP or Registers
      3. 7.5.3 Device Security
      4. 7.5.4 Scratchpad Memory
    6. 7.6  Measurement Subsystem
      1. 7.6.1  Voltage Measurement
        1. 7.6.1.1 Voltage Measurement Schedule
        2. 7.6.1.2 Usage of VC Pins for Cells Versus Interconnect
        3. 7.6.1.3 Cell 1 Voltage Validation During SLEEP Mode
      2. 7.6.2  General Purpose ADCIN Functionality
      3. 7.6.3  Coulomb Counter and Digital Filters
      4. 7.6.4  Synchronized Voltage and Current Measurement
      5. 7.6.5  Internal Temperature Measurement
      6. 7.6.6  Thermistor Temperature Measurement
      7. 7.6.7  Factory Trim of Voltage ADC
      8. 7.6.8  Cell Voltage Measurement Accuracy
        1. 7.6.8.1 Fixed Offset Adjustment
        2. 7.6.8.2 Cell Offset Calibration
      9. 7.6.9  Voltage Calibration (ADC Measurements)
      10. 7.6.10 Voltage Calibration (COV and CUV Protections)
      11. 7.6.11 Current Calibration
      12. 7.6.12 Temperature Calibration
    7. 7.7  Primary and Secondary Protection Subsystems
      1. 7.7.1 Protections Overview
      2. 7.7.2 Primary Protections
      3. 7.7.3 Secondary Protections
      4. 7.7.4 High-Side NFET Drivers
      5. 7.7.5 Protection FETs Configuration and Control
        1. 7.7.5.1 FET Configuration
        2. 7.7.5.2 PRECHARGE and PREDISCHARGE Modes
      6. 7.7.6 Load Detect Functionality
    8. 7.8  Device Hardware Features
      1. 7.8.1  Voltage References
      2. 7.8.2  ADC Multiplexer
      3. 7.8.3  LDOs
        1. 7.8.3.1 Preregulator Control
        2. 7.8.3.2 REG1 and REG2 LDO Controls
      4. 7.8.4  Standalone Versus Host Interface
      5. 7.8.5  Multifunction Pin Controls
      6. 7.8.6  RST_SHUT Pin Operation
      7. 7.8.7  CFETOFF, DFETOFF, and BOTHOFF Pin Functionality
      8. 7.8.8  ALERT Pin Operation
      9. 7.8.9  DDSG and DCHG Pin Operation
      10. 7.8.10 Fuse Drive
      11. 7.8.11 Cell Open Wire
      12. 7.8.12 Low Frequency Oscillator
      13. 7.8.13 High Frequency Oscillator
    9. 7.9  Device Functional Modes
      1. 7.9.1 Overview
      2. 7.9.2 NORMAL Mode
      3. 7.9.3 SLEEP Mode
      4. 7.9.4 DEEPSLEEP Mode
      5. 7.9.5 SHUTDOWN Mode
      6. 7.9.6 CONFIG_UPDATE Mode
    10. 7.10 Serial Communications Interface
      1. 7.10.1 Serial Communications Overview
      2. 7.10.2 I2C Communications
      3. 7.10.3 SPI Communications
        1. 7.10.3.1 SPI Protocol
      4. 7.10.4 HDQ Communications
    11. 7.11 Cell Balancing
      1. 7.11.1 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
    7. 8.7 Power Supply Requirements
    8. 8.8 Layout
      1. 8.8.1 Layout Guidelines
      2. 8.8.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, Orderable Information

Package Options

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

7.5.3 Device Security

The BQ76972 device includes three security modes: SEALED, UNSEALED, and FULLACCESS, which can be used to limit the ability to view or change settings.

  • In SEALED mode, most data and status can be read using commands and subcommands, but only selected settings can be changed. Data memory settings cannot be changed directly.
  • UNSEALED mode includes SEALED functionality, and also adds the ability to execute additional subcommands, and read and write data memory.
  • FULLACCESS mode allows capability to read and modify all device settings, including writing OTP memory.

Selected settings in the device can be modified while the device is in operation through supported commands and subcommands, but in order to modify all settings, the device must enter CONFIG_UPDATE mode (see Section 7.9.6), which stops device operation while settings are being updated. After the update is completed, the operation is restarted using the new settings. CONFIG_UPDATE mode is only available in FULLACCESS mode.

The BQ76972 device implements a key-access scheme to transition among SEALED, UNSEALED, and FULLACCESS modes. Each transition requires that a unique set of keys be sent to the device through subcommands. Refer to the BQ76972 Technical Reference Manual for more details.

The device provides additional checks which can be used to optimize system robustness, including subcommands which calculate the digital signature of the integrated instruction ROM and data ROM. These signatures should never change for a particular product. If these were to change, it would indicate an error, either that the ROM had been corrupted, or the readback of the ROM or calculation of the signature experienced an error. An additional subcommand calculates a digital signature for the static configuration data (which excludes calibration values) and compares it to a stored value, returning a flag if the result does not match.