SLUSBV4B June   2018  – September 2020 BQ40Z80

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Primary (1st Level) Safety Features
      2. 8.3.2  Secondary (2nd Level) Safety Features
      3. 8.3.3  Charge Control Features
      4. 8.3.4  Gas Gauging
      5. 8.3.5  Multifunction Pins
      6. 8.3.6  Configuration
        1. 8.3.6.1 Oscillator Function
        2. 8.3.6.2 System Present Operation
        3. 8.3.6.3 Emergency Shutdown
        4. 8.3.6.4 2-Series, 3-Series, 4-Series, 5-Series, or 6-Series Cell Configuration
        5. 8.3.6.5 Cell Balancing
      7. 8.3.7  Battery Parameter Measurements
        1. 8.3.7.1 Charge and Discharge Counting
      8. 8.3.8  Lifetime Data Logging Features
      9. 8.3.9  Authentication
      10. 8.3.10 LED Display
      11. 8.3.11 IATA Support
      12. 8.3.12 Voltage
      13. 8.3.13 Current
      14. 8.3.14 Temperature
      15. 8.3.15 Communications
        1. 8.3.15.1 SMBus On and Off State
        2. 8.3.15.2 SBS Commands
    4. 8.4 Device Functional Modes
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Using the BQ40Z80EVM with BQSTUDIO
        2. 9.2.2.2 High-Current Path
          1. 9.2.2.2.1 Protection FETs
          2. 9.2.2.2.2 Chemical Fuse
          3. 9.2.2.2.3 Lithium-Ion Cell Connections
          4. 9.2.2.2.4 Sense Resistor
          5. 9.2.2.2.5 ESD Mitigation
        3. 9.2.2.3 Gas Gauge Circuit
          1. 9.2.2.3.1 Coulomb-Counting Interface
          2. 9.2.2.3.2 Power Supply Decoupling and PBI
          3. 9.2.2.3.3 System Present
          4. 9.2.2.3.4 SMBus Communication
          5. 9.2.2.3.5 FUSE Circuitry
        4. 9.2.2.4 Secondary-Current Protection
          1. 9.2.2.4.1 Cell and Battery Inputs
          2. 9.2.2.4.2 External Cell Balancing
          3. 9.2.2.4.3 PACK and FET Control
          4. 9.2.2.4.4 Pre-Discharge Control
          5. 9.2.2.4.5 Temperature Output
          6. 9.2.2.4.6 LEDs
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Protector FET Bypass and Pack Terminal Bypass Capacitors
      2. 11.1.2 ESD Spark Gap
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

The chemical fuse (Dexerials, Uchihashi, and so on) is ignited under command from either the bq771800 secondary voltage protection IC or from the FUSE pin of the gas gauge. Either of these events applies a positive voltage to the gate of Q9, which then sinks current from the third terminal of the fuse, causing it to ignite and open permanently.

It is important to carefully review the fuse specifications and match the required ignition current to that available from the N-CH FET. Ensure that the proper voltage, current, and Rds(on) ratings are used for this device. The fuse control circuit is discussed in detail in Section 9.2.2.3.5.