SLUSCM6E June   2016  – April 2019 BQ35100

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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  Power Supply Current Static Modes
    6. 6.6  Digital Input and Outputs
    7. 6.7  Power-On Reset
    8. 6.8  LDO Regulator
    9. 6.9  Internal Temperature Sensor
    10. 6.10 Internal Clock Oscillators
    11. 6.11 Integrating ADC (Coulomb Counter)
    12. 6.12 ADC (Temperature and Voltage Measurements)
    13. 6.13 Data Flash Memory
    14. 6.14 I2C-Compatible Interface Timing Characteristics
    15. 6.15 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 Basic Measurement Systems
        1. 7.3.1.1 Voltage
        2. 7.3.1.2 Temperature
        3. 7.3.1.3 Coulombs
        4. 7.3.1.4 Current
      2. 7.3.2 Battery Gauging
        1. 7.3.2.1 ACCUMULATOR (ACC) Mode
        2. 7.3.2.2 STATE-OF-HEALTH (SOH) Mode
          1. 7.3.2.2.1 Low State-of-Health Alert
        3. 7.3.2.3 END-OF-SERVICE (EOS) Mode
          1. 7.3.2.3.1 Initial EOS Learning
            1. 7.3.2.3.1.1 End-Of-Service Detection
      3. 7.3.3 Power Control
      4. 7.3.4 Battery Condition Warnings
        1. 7.3.4.1 Battery Low Warning
        2. 7.3.4.2 Temperature Low Warning
        3. 7.3.4.3 Temperature High Warning
        4. 7.3.4.4 Battery Low SOH Warning
        5. 7.3.4.5 Battery EOS OCV BAD Warning
      5. 7.3.5 ALERT Signal
      6. 7.3.6 Lifetime Data Collection
      7. 7.3.7 SHA-1 Authentication
      8. 7.3.8 Data Commands
        1. 7.3.8.1 Command Summary
        2. 7.3.8.2 0x00, 0x01 AltManufacturerAccess() and 0x3E, 0x3F AltManufacturerAccess()
        3. 7.3.8.3 Control(): 0x00/0x01
      9. 7.3.9 Communications
        1. 7.3.9.1 I2C Interface
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Preparation for Gauging
        2. 8.2.2.2 Gauging Mode Selection
          1. 8.2.2.2.1 ACCUMULATOR Mode
            1. 8.2.2.2.1.1 STATE-OF-HEALTH (Voltage Correlation) Mode
            2. 8.2.2.2.1.2 END-OF-SERVICE (Resistance Correlation) Mode
        3. 8.2.2.3 Voltage Measurement Selection
        4. 8.2.2.4 Temperature Measurement Selection
        5. 8.2.2.5 Current Sense Resistor Selection
        6. 8.2.2.6 Expected Device Usage Profiles
        7. 8.2.2.7 Using the BQ35100 Fuel Gauge with a Battery and Capacitor in Parallel
          1. 8.2.2.7.1 ACCUMULATOR Mode
          2. 8.2.2.7.2 STATE-OF-HEALTH Mode
          3. 8.2.2.7.3 END-OF-SERVICE Mode
      3. 8.2.3 EOS Mode Load Pulse Synchronization
      4. 8.2.4 Benefits of the BQ35100 Gauge Compared to Alternative Monitoring Techniques
      5. 8.2.5 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Introduction
      2. 10.1.2 Power Supply Decoupling Capacitor
      3. 10.1.3 Capacitors
      4. 10.1.4 Communication Line Protection Components
    2. 10.2 Layout Example
      1. 10.2.1 Ground System
      2. 10.2.2 Kelvin Connections
      3. 10.2.3 Board Offset Considerations
    3. 10.3 ESD Spark Gap
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.4 Benefits of the BQ35100 Gauge Compared to Alternative Monitoring Techniques

The BQ35100 gauge offers many capabilities and provides a level of accuracy that alternative monitoring techniques cannot offer. One of the main techniques is to use a voltage lookup table implemented with an MCU and integrated ADC.

Table 4. BQ35100 Compared to MCU + ADC

Operation Advantages Disadvantages
Characterize the cells' performance under the expected load condition to create a voltage versus SOH table to measure voltage and temperature and compare the measurements to the characterized table.
  • Easy to implement
  • Accounts for early cell degradation
  • Most system host microcontrollers have a spare ADC channel.
  • Only uses a small amount of memory and CPU operation.
  • The table can be updated if the system load configuration is changed (for example, FW Update).
  • No simple accounting for cell-to-cell or temperature variation
  • No simple accounting for installation variations, such as radio power due to transmit distances
  • Assumptions and tolerances must be built into the original cell capacity, forcing a much larger, more expensive cell to be used.
  • Cell voltage is very flat so a small voltage measurement error is a very large capacity error.
    • LiSoCl2: 95% of SOC is 100 mV of voltage.
    • A typical MCU ADC of 10-bit resolution has only seven bits of accurate performance, providing a 36-mV resolution.

In summary, the voltage measurement performance of the measurement system is critical to this technique and that is typically not available from the host MCU.