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
9.2.2.2.1 Protection FETs

Select the N-CH charge and discharge FETs for a given application. For a 7-series cell application, the charge FET must be rated above the max voltage, and for this reason the TI CSD18504Q5A is used. The TI CSD18504Q5A is a 50-A, 40-V device with Rds(on) of 5.3 mΩ when the gate drive voltage is 10 V. For the discharge FET, it may see a higher voltage, and so the TI CSD18540Q5B is used. The TI CSD18540Q5B is a 100-A, 60-V device with Rds(on) of 1.8 mΩ when the gate drive voltage is 10 V.

If a precharge FET is used, R2 is calculated to limit the precharge current to the desired rate. Be sure to account for the power dissipation of the series resistor. The precharge current is limited to (VCHARGER – VBAT)/R2 and maximum power dissipation is (VCHARGER – VBAT)2/R2.

The gates of all protection FETs are pulled to the source with a high-value resistor between the gate and source to ensure they are turned off if the gate drive is open.

Capacitors C1 and C2 help protect the FETs during an ESD event. Using two devices ensures normal operation if one becomes shorted. To have good ESD protection, the copper trace inductance of the capacitor leads must be designed to be as short and wide as possible. Ensure that the voltage rating of both C1 and C2 are adequate to hold off the applied voltage if one of the capacitors becomes shorted.