SLUSFM5 March   2025 BQ76907-Q1

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 BQ76907-Q1
    5. 6.5  Supply Current
    6. 6.6  Digital I/O
    7. 6.7  REGOUT LDO
    8. 6.8  Voltage References
    9. 6.9  Coulomb Counter
    10. 6.10 Coulomb Counter Digital Filter
    11. 6.11 Current Wake Detector
    12. 6.12 Analog-to-Digital Converter
    13. 6.13 Cell Voltage Measurement Accuracy
    14. 6.14 Cell Balancing
    15. 6.15 Internal Temperature Sensor
    16. 6.16 Thermistor Measurement
    17. 6.17 Hardware Overtemperature Detector
    18. 6.18 Internal Oscillator
    19. 6.19 Charge and Discharge FET Drivers
    20. 6.20 Comparator-Based Protection Subsystem
    21. 6.21 Timing Requirements - I2C Interface, 100kHz Mode
    22. 6.22 Timing Requirements - I2C Interface, 400kHz Mode
    23. 6.23 Timing Diagram
    24. 6.24 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Device Configuration
      1. 7.3.1 Commands and Subcommands
      2. 7.3.2 Configuration Using OTP or Registers
      3. 7.3.3 Device Security
    4. 7.4 Device Hardware Features
      1. 7.4.1  Voltage ADC
      2. 7.4.2  Coulomb Counter and Digital Filters
      3. 7.4.3  Protection FET Drivers
      4. 7.4.4  Voltage References
      5. 7.4.5  Multiplexer
      6. 7.4.6  LDOs
      7. 7.4.7  Standalone Versus Host Interface
      8. 7.4.8  ALERT Pin Operation
      9. 7.4.9  Low Frequency Oscillator
      10. 7.4.10 I2C Serial Communications Interface
    5. 7.5 Measurement Subsystem
      1. 7.5.1 Voltage Measurement
        1. 7.5.1.1 Voltage ADC Scheduling
        2. 7.5.1.2 Unused VC Pins
        3. 7.5.1.3 General Purpose ADCIN Functionality
      2. 7.5.2 Current Measurement and Charge Integration
      3. 7.5.3 Internal Temperature Measurement
      4. 7.5.4 Thermistor Temperature Measurement
      5. 7.5.5 Factory Trim and Calibration
    6. 7.6 Protection Subsystem
      1. 7.6.1 Protections Overview
      2. 7.6.2 Primary Protections
      3. 7.6.3 CHG Detector
      4. 7.6.4 Cell Open-Wire Protection
      5. 7.6.5 Diagnostic Checks
    7. 7.7 Cell Balancing
    8. 7.8 Device Operational Modes
      1. 7.8.1 Overview of Operational Modes
      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. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Performance Plot
      4. 8.2.4 Random Cell Connection Support
      5. 8.2.5 Startup Timing
      6. 8.2.6 FET Driver Turn-Off
      7. 8.2.7 Usage of Unused Pins
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.5.1.2 Unused VC Pins

If the BQ76907-Q1 device is used in a system with fewer than 7-series cells, specific cells must be used for connection to real cells, as shown in Table 7-1. The unused cell inputs should be shorted out on the circuit board. The device only measures and reports data for those cells designated as real cells.

Table 7-1 Cell Usage
Number of Cell UsedCell ConnectionsShorted Connections
7VC7‒VC6, VC6‒VC5, VC5‒VC4, VC4‒VC3, VC3‒VC2, VC2‒VC1, VC1‒VC0‒
6VC7‒VC6, VC6‒VC5, VC5‒VC4, VC3‒VC2, VC2‒VC1, VC1‒VC0VC4‒VC3
5VC7‒VC6, VC5‒VC4, VC3‒VC2, VC2‒VC1, VC1‒VC0VC6‒VC5, VC4‒VC3
4VC7‒VC6, VC5‒VC4, VC3‒VC2, VC1‒VC0VC6‒VC5, VC4‒VC3, VC2‒VC1
3VC7‒VC6, VC5‒VC4, VC1‒VC0VC6‒VC5, VC4‒VC3, VC3‒VC2, VC2‒VC1
2VC7‒VC6, VC1‒VC0VC6‒VC5, VC5‒VC4,VC4‒VC3, VC3‒VC2, VC2‒VC1

The unused cell input pins should be shorted to adjacent cell input pins, as shown in Figure 7-4 for a 6-series system.

It is also important to note that the range of voltages supported by the different VC pins differs depending on the pin. For example, pins VC5, VC6, and VC7 can only support measurements if their pin voltage is greater than or equal to 2V. Thus if implementing a 2-series system using the top and bottom cell input pins, the upper cell voltage may not be measured correctly if the lower cell voltage drops below 2V, since then VC6 would be below 2V.


BQ76907-Q1 Connecting an Unused Cell Input Pin

Figure 7-4 Connecting an Unused Cell Input Pin

The device data memory must be configured to specify which cell inputs are used for actual cells. The device uses this information to disable cell voltage protections associated with inputs that are not used. Voltage measurements for inputs used for real cells are reported in 16-bit format (in units of mV). See the BQ76907-Q1 Technical Reference Manual for further details.