SLUSB23B October   2012  – June 2015 BQ27425-G2A , BQ27425-G2B

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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: Power-On Reset
    6. 7.6  2.5-V LDO Regulator
    7. 7.7  Integrating ADC (Coulomb Counter) Characteristics
    8. 7.8  Integrated Sense Resistor Characteristics
    9. 7.9  ADC (Temperature and Cell Measurement) Characteristics
    10. 7.10 EEPROM Memory Characteristics
    11. 7.11 Timing Requirements: I2C-Compatible Interface Communication
    12. 7.12 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 Fuel Gauging
      2. 8.3.2 Fuel Gauging Configurations
        1. 8.3.2.1 SOC Smoothing Feature
      3. 8.3.3 GPOUT Pin
      4. 8.3.4 Battery Detection (BIN)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operating Modes
        1. 8.4.1.1 POR and INITIALIZATION Modes
        2. 8.4.1.2 CONFIG UPDATE Mode
        3. 8.4.1.3 NORMAL Mode
        4. 8.4.1.4 SLEEP Mode
        5. 8.4.1.5 HIBERNATE Mode
    5. 8.5 Programming
      1. 8.5.1 Standard Data Commands
        1. 8.5.1.1  Control(): 0x00 and 0x01
          1. 8.5.1.1.1  CONTROL_STATUS: 0x0000
          2. 8.5.1.1.2  DEVICE_TYPE: 0x0001
          3. 8.5.1.1.3  FW_VERSION: 0x0002
          4. 8.5.1.1.4  PREV_MACWRITE: 0x0007
          5. 8.5.1.1.5  CHEM_ID: 0x0008
          6. 8.5.1.1.6  BAT_INSERT: 0X000C
          7. 8.5.1.1.7  BAT_REMOVE: 0X000D
          8. 8.5.1.1.8  SET_HIBERNATE: 0x0011
          9. 8.5.1.1.9  CLEAR_HIBERNATE: 0x0012
          10. 8.5.1.1.10 SET_CFGUPDATE: 0x0013
          11. 8.5.1.1.11 SEALED: 0x0020
          12. 8.5.1.1.12 RESET: 0x0041
          13. 8.5.1.1.13 SOFT_RESET: 0x0042
        2. 8.5.1.2  Temperature( ): 0x02 and 0x03
        3. 8.5.1.3  Voltage( ): 0x04 and 0x05
        4. 8.5.1.4  Flags( ): 0x06 and 0x07
        5. 8.5.1.5  NominalAvailableCapacity( ): 0x08 and 0x09
        6. 8.5.1.6  FullAvailableCapacity( ): 0x0A and 0x0B
        7. 8.5.1.7  RemainingCapacity( ): 0x0C and 0x0D
        8. 8.5.1.8  FullChargeCapacity( ): 0x0E and 0x0F
        9. 8.5.1.9  AverageCurrent( ): 0x10 and 0x11
        10. 8.5.1.10 AveragePower( ): 0x18 and 0x19
        11. 8.5.1.11 StateOfCharge( ): 0x1C and 0x1D
        12. 8.5.1.12 IntTemperature( ): 0x1E and 0x1F
        13. 8.5.1.13 StateOfHealth( ): 0x20 and 0x21
        14. 8.5.1.14 OperationConfiguration( ): 0x3A and 0x3B
        15. 8.5.1.15 DesignCapacity( ): 0x3C and 0x3D
        16. 8.5.1.16 DebugX( ):
      2. 8.5.2 Extended Data Commands
        1. 8.5.2.1 OperationConfiguration( ): 0x3A and 0x3B
        2. 8.5.2.2 DesignCapacity( ): 0x3C and 0x3D
        3. 8.5.2.3 DataClass( ): 0x3E
        4. 8.5.2.4 DataBlock( ): 0x3F
        5. 8.5.2.5 BlockData( ): 0x40 through 0x5F
        6. 8.5.2.6 BlockDataChecksum( ): 0x60
        7. 8.5.2.7 BlockDataControl( ): 0x61
        8. 8.5.2.8 Reserved: 0x62 through 0x7F
      3. 8.5.3 Block Data Interface
        1. 8.5.3.1 Accessing Block Data
      4. 8.5.4 Access Modes
        1. 8.5.4.1 Sealing and Unsealing Data Blocks
      5. 8.5.5 Data Block Summary
      6. 8.5.6 Detecting Charge Termination
      7. 8.5.7 Communications
        1. 8.5.7.1 I2C Interface
        2. 8.5.7.2 I2C Time Out
        3. 8.5.7.3 I2C Command Waiting Time
        4. 8.5.7.4 I2C Clock Stretching
    6. 8.6 Register Maps
      1. 8.6.1 Operation Configuration (Op Config) Register
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 BAT/REGIN Voltage Sense Input
        2. 9.2.2.2 Integrated LDO Capacitor
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Power Supply Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Community Resources
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 Packaging
      1. 13.1.1 Package Dimensions

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The Texas Instruments bq27425-G2 fuel gauge is a microcontroller peripheral that provides system-side fuel gauging for single-cell Li-Ion batteries. The device requires minimal user configuration and system microcontroller firmware. Battery fuel gauging with the bq27425-G2 fuel gauge requires connections only to PACK+ (P+) and PACK– for a removable battery pack or embedded battery circuit.

9.2 Typical Application

bq27425-G2 sch_bq27425-G2.gif Figure 11. Reference (EVM) Schematic

9.2.1 Design Requirements

As shipped from the TI factory, many bq27425-G2 parameters in NVM are left in the unprogrammed state (zero) while some parameters directly associated with the CHEMID are preprogrammed. This partially programmed configuration facilitates customization for each end application. Upon device reset, the contents of NVM are copied to associated volatile RAM-based Data Memory blocks. For proper operation, all parameters in RAM-based Data Memory require initialization — either by updating Data Memory parameters in a lab or evaluation situation or by programming the NVM for customer production.

Table 9 shows the design parameter values that are present in the device.

9.2.2 Detailed Design Procedure

9.2.2.1 BAT/REGIN Voltage Sense Input

A ceramic capacitor at the input to the BAT/REGIN pin is used to bypass AC voltage ripple to ground, greatly reducing its influence on battery voltage measurements. It proves most effective in applications with load profiles that exhibit high-frequency current pulses (that is, cell phones) but is recommended for use in all applications to reduce noise on this sensitive high-impedance measurement node.

9.2.2.2 Integrated LDO Capacitor

The fuel gauge has an integrated LDO with an output on the VCC pin of approximately 2.5 V. A capacitor of value at least 1 μF should be connected between the VCC pin and VSS. The capacitor should be placed close to the gauge IC and have short traces to both the VCC pin and VSS.

9.2.3 Application Curves

bq27425-G2 D001_SLUSBU6.gif Figure 12. Regulator Output Voltage vs Temperature
bq27425-G2 D003_SLUSBU6.gif Figure 14. Low-Frequency Oscillator Frequency vs Temperature
bq27425-G2 D002_SLUSBU6.gif Figure 13. High-Frequency Oscillator Frequency vs Temperature
bq27425-G2 D004_SLUSBU6.gif Figure 15. Reported Internal Temperature Measurement vs Temperature