SLUSDW2A November   2021  – February 2022 BQ27Z746

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configurations and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
      1. 6.5.1 Supply Current
      2. 6.5.2 Common Analog (LDO, LFO, HFO, REF1, REF2, I-WAKE)
      3. 6.5.3 Battery Protection (CHG, DSG)
      4. 6.5.4 Cell Sensing Output (BAT_SP, BAT_SN)
      5. 6.5.5 Gauge Measurements (ADC, CC, Temperature)
      6. 6.5.6 Flash Memory
    6. 6.6 Digital I/O: DC Characteristics
    7. 6.7 Digital I/O: Timing Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  BQ27Z746 Processor
      2. 7.3.2  Battery Parameter Measurements
        1. 7.3.2.1 Coulomb Counter (CC) and Digital Filter
        2. 7.3.2.2 ADC Multiplexer
        3. 7.3.2.3 Analog-to-Digital Converter (ADC)
        4. 7.3.2.4 Internal Temperature Sensor
        5. 7.3.2.5 External Temperature Sensor Support
      3. 7.3.3  Power Supply Control
      4. 7.3.4  Bus Communication Interface
      5. 7.3.5  Low Frequency Oscillator
      6. 7.3.6  High Frequency Oscillator
      7. 7.3.7  1.8-V Low Dropout Regulator
      8. 7.3.8  Internal Voltage References
      9. 7.3.9  Overcurrent in Discharge Protection
      10. 7.3.10 Overcurrent in Charge Protection
      11. 7.3.11 Short-Circuit Current in Discharge Protection
      12. 7.3.12 Primary Protection Features
      13. 7.3.13 Battery Sensing
      14. 7.3.14 Gas Gauging
      15. 7.3.15 Zero Volt Charging (ZVCHG)
      16. 7.3.16 Charge Control Features
      17. 7.3.17 Authentication
    4. 7.4 Device Functional Modes
      1. 7.4.1 Lifetime Logging Features
      2. 7.4.2 Configuration
        1. 7.4.2.1 Coulomb Counting
        2. 7.4.2.2 Cell Voltage Measurements
        3. 7.4.2.3 Auto Calibration
        4. 7.4.2.4 Temperature Measurements
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements (Default)
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Changing Design Parameters
      3. 8.2.3 Calibration Process
      4. 8.2.4 Gauging Data Updates
        1. 8.2.4.1 Application Curve
  9. 9 Power Supply Requirements
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Orderable, and Packaging Information

Package Options

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

7.3.13 Battery Sensing

The BQ27Z746 offers direct battery sensing through differential battery sensing pins BAT_SP and BAT_SN for accurate battery voltage measurement and detection. BQ27Z746 battery sensing path includes protection and isolation to minimize any leakage and coupling issue. The cell isolation includes a combination of buffered and resistive options. Firmware configuration allows seamless auto-transition between the two sensing schemes. The battery sensing buffer is powered from the PACK pin.

For accurate battery voltage sensing when using the sensing buffer, the PACK pin must be powered and VPACK > VBAT + 0.7 V. The sensing protection thresholds (BCP, BCN, BDP, and BDN) provide short detection for the battery sensing output pins, and places the battery sensing output pins in a high impedance state when triggered. The BQ27Z746 battery sensing has firmware programmable offset options for applications where differential output voltage needs to be shifted to overcome an input range limitation. The offset voltage selected should never exceed the sensing protection thresholds, because this causes false battery sensing faults.