SLUUB65B May   2015  – December 2022

 

  1.   Read This First
    1.     Formatting Conventions Used in This Document
    2.     Related Documentation from Texas Instruments
    3.     Trademarks
  2. 1 Introduction
  3. 2 Basic Measurement System
    1. 2.1 Introduction
    2. 2.2 Current and Coulomb Counting
    3. 2.3 Voltage
    4. 2.4 Temperature
  4. 3 Device Power Modes
    1. 3.1 Introduction
      1. 3.1.1 NORMAL Mode
      2. 3.1.2 SLEEP Mode
      3. 3.1.3 FULLSLEEP Mode
      4. 3.1.4 HIBERNATE Mode
    2. 3.2 Power Control
      1. 3.2.1 Reset Functions
      2. 3.2.2 Wake-Up Comparator
      3. 3.2.3 Flash Updates
  5. 4 Device Configuration Registers
    1. 4.1 Introduction
    2. 4.2 Registers Subclass
      1. 4.2.1 Pack Configuration Register
      2. 4.2.2 Pack Configuration B Register
      3. 4.2.3 Pack Configuration C Register
      4. 4.2.4 Pack Configuration D
  6. 5 System Control Function
    1. 5.1 Introduction
    2. 5.2 SHUTDOWN Mode
    3. 5.3 INTERRUPT Mode
    4. 5.4 Low Capacity
    5. 5.5 Battery Level
    6. 5.6 Safety Conditions
      1. 5.6.1 Overtemperature Fault Conditions During Charge/Discharge
      2. 5.6.2 Tab Disconnect Detection
      3. 5.6.3 ISD Faults
    7. 5.7 Battery Trip Point Interrupt Function
  7. 6 Impedance Track Fuel Gauging
    1. 6.1 Introduction
      1. 6.1.1 System Design Parameters
        1. 6.1.1.1 Design Voltage
        2. 6.1.1.2 Cycle Count
        3. 6.1.1.3 Cycle Count Threshold
        4. 6.1.1.4 Design Capacity
        5. 6.1.1.5 Design Energy
        6. 6.1.1.6 State of Health Load I
        7. 6.1.1.7 Design Energy Scale
        8. 6.1.1.8 System Design Parameters DF
    2. 6.2 Gauge FW Operation Modes
      1. 6.2.1 CHARGE Mode
      2. 6.2.2 RELAXATION Mode
      3. 6.2.3 DISCHARGE Mode
    3. 6.3 Current/Power Profiles
      1. 6.3.1 Load Select
      2. 6.3.2 Thermal Rise Factor
      3. 6.3.3 Thermal Time Constant
    4. 6.4 Qmax Update
      1. 6.4.1 Charge Hysteresis Voltage Shift
    5. 6.5 Fast Qmax Update
    6. 6.6 Resistance Update
    7. 6.7 Fast Resistance Scaling
    8. 6.8 StateOfCharge() Smoothing
      1. 6.8.1 SOC Smoothing in Charge/Discharge
      2. 6.8.2 SOC Smoothing in Relaxation
      3. 6.8.3 SOC Smoothing in Overcharge and Overdischarge Conditions
      4. 6.8.4 StateofCharge() Hold at 99%
      5. 6.8.5 StateofCharge() Hold at 1%
    9. 6.9 Additional Impedance Track Gauging Features
      1. 6.9.1 Trace and Downstream Resistance Compensation
      2. 6.9.2 Imax Calculation
      3. 6.9.3 Predict Outside Temp Time
      4. 6.9.4 State Subclass
        1. 6.9.4.1 Qmax Cell 0
        2. 6.9.4.2 Update Status
      5. 6.9.5 OCV Table Class
        1. 6.9.5.1 OCVa Table Subclass
          1. 6.9.5.1.1 Chemistry Identification
      6. 6.9.6 Ra Table Class
        1. 6.9.6.1 Ra0 Subclass
        2. 6.9.6.2 Ra0x Subclass
  8. 7 Charging Features
    1. 7.1 Introduction
    2. 7.2 Charge Suspend
    3. 7.3 Charge Inhibit
    4. 7.4 JEITA Charging Profile
    5. 7.5 Full Charge Termination Detection
    6. 7.6 Pulse Loads
    7. 7.7 Terminate Voltage Valid Time
    8. 7.8 Charge Termination Subclass
      1. 7.8.1 DOD at EOC Delta Temperature
  9. 8 Lifetime Data Logging Features
    1. 8.1 Introduction
    2. 8.2 Lifetime Data Logging Parameters
    3. 8.3 Feature Access
    4. 8.4 Lifetime Data Subclass, Lifetime Resolution Subclass
      1. 8.4.1 Maximum Temperature, Minimum Temperature, Temperature Resolution
      2. 8.4.2 Maximum Pack Voltage, Minimum Pack Voltage, Voltage Resolution
      3. 8.4.3 Maximum Charge Current, Maximum Discharge Current, Current Resolution
    5. 8.5 Lifetime Resolution Subclass
      1. 8.5.1 Lifetime Update Time
    6. 8.6 Lifetime Temp Samples Subclass
      1. 8.6.1 Flash Write Count
  10. 9 Authentication
    1. 9.1 Introduction
    2. 9.2 Key Programming (Data Flash Key)
    3. 9.3 Key Programming (Secure Memory Key)
    4. 9.4 Executing an Authentication Query
    5. 9.5 Codes Subclass
      1. 9.5.1 Sealed to Unsealed
      2. 9.5.2 Unsealed to Full Access
      3. 9.5.3 Authentication Keys
  11. 10Communications
    1. 10.1 HDQ Single-Pin Serial Interface
    2. 10.2 HDQ Host Interruption Feature
      1. 10.2.1 Low Battery Capacity
      2. 10.2.2 Temperature
    3. 10.3 I2C Interface
      1. 10.3.1 I2C Time Out
      2. 10.3.2 I2C Command Waiting Time
      3. 10.3.3 I2C Clock Stretching
  12. 11Manufacturer Information
    1. 11.1 Manufacturer Information Blocks
    2. 11.2 Manufacturer Information Subclass
      1. 11.2.1 Block A and Block B
  13. 12Manufacturer Data
    1. 12.1 Introduction
    2. 12.2 Manufacturer Data Subclass
      1. 12.2.1 Pack Lot Code
      2. 12.2.2 PCB Lot Code
      3. 12.2.3 Firmware Version
      4. 12.2.4 Hardware Revision
      5. 12.2.5 Cell Revision
      6. 12.2.6 Data Flash Configuration Version
  14. 13Integrity Data or Checksum
    1. 13.1 Introduction
    2. 13.2 Data Flash Checksum
  15. 14Calibration
    1. 14.1 Introduction
    2. 14.2 Current Calibration
    3. 14.3 Offset Calibration
      1. 14.3.1 Coulomb Counter Offset/Board Offset
      2. 14.3.2 Internal/External Temperature Offset
      3. 14.3.3 Pack Voltage Offset
      4. 14.3.4 145
    4. 14.4 Current Measurement Noise Filtering
      1. 14.4.1 Filter
      2. 14.4.2 Deadband
      3. 14.4.3 CC Deadband
      4. 14.4.4 150
  16. 15Data Commands
    1. 15.1 Standard Data Commands
      1. 15.1.1  Control(): 0x00 and 0x01
        1. 15.1.1.1  CONTROL_STATUS: 0x0000
        2. 15.1.1.2  DEVICE_TYPE: 0x0001
        3. 15.1.1.3  FW_VERSION: 0x0002
        4. 15.1.1.4  HW_VERSION: 0x0003
        5. 15.1.1.5  RESET_DATA: 0x0005
        6. 15.1.1.6  PREV_MACWRITE: 0x0007
        7. 15.1.1.7  CHEM_ID: 0x0008
        8. 15.1.1.8  BOARD_OFFSET: 0x0009
        9. 15.1.1.9  CC_OFFSET: 0x000A
        10. 15.1.1.10 DF_VERSION: 0x000C
        11. 15.1.1.11 SET_FULLSLEEP: 0x0010
        12. 15.1.1.12 SET_HIBERNATE: 0x0011
        13. 15.1.1.13 CLEAR_HIBERNATE: 0x0012
        14. 15.1.1.14 SET_SHUTDOWN: 0x0013
        15. 15.1.1.15 CLEAR_SHUTDOWN: 0x0014
        16. 15.1.1.16 SET_HDQINTEN: 0x0015
        17. 15.1.1.17 CLEAR_HDQINTEN: 0x0016
        18. 15.1.1.18 STATIC_CHEM_CHKSUM: 0x0017
        19. 15.1.1.19 ALL_DF_CHKSUM: 0x0018
        20. 15.1.1.20 STATIC_DF_CHKSUM: 0x0019
        21. 15.1.1.21 SYNC_SMOOTH: 0x001E
        22. 15.1.1.22 SEALED: 0x0020
        23. 15.1.1.23 IT ENABLE: 0x0021
        24. 15.1.1.24 IMAX_INT_CLEAR: 0x0023
        25. 15.1.1.25 CAL_ENABLE: 0x002D
        26. 15.1.1.26 RESET: 0x0041
        27. 15.1.1.27 EXIT_CAL: 0x0080
        28. 15.1.1.28 ENTER_CAL: 0x0081
        29. 15.1.1.29 OFFSET_CAL: 0x0082
      2. 15.1.2  AtRate(): 0x02 and 0x03
      3. 15.1.3  UnfilteredSOC(): 0x04 and 0x05
      4. 15.1.4  Temperature(): 0x06 and 0x07
      5. 15.1.5  Voltage(): 0x08 and 0x09
      6. 15.1.6  Flags(): 0x0A and 0x0B
      7. 15.1.7  NomAvailableCapacity(): 0x0C and 0x0D
      8. 15.1.8  FullAvailableCapacity(): 0x0E and 0x0F
      9. 15.1.9  RemainingCapacity(): 0x10 and 0x11
      10. 15.1.10 FullChargeCapacity(): 0x12 and 0x13
      11. 15.1.11 AverageCurrent(): 0x14 and 0x15
      12. 15.1.12 TimeToEmpty(): 0x16 and 0x17
      13. 15.1.13 FilteredFCC(): 0x18 and 0x19
      14. 15.1.14 SafetyStatus(): 0x1A and 0x1B
      15. 15.1.15 UnfilteredFCC(): 0x1C and 0x1D
      16. 15.1.16 Imax(): 0x1E and 0x1F
      17. 15.1.17 UnfilteredRM(): 0x20 and 0x21
      18. 15.1.18 FilteredRM(): 0x22 and 0x23
      19. 15.1.19 BTPSOC1Set(): 0x24 and 0x25
      20. 15.1.20 BTPSOC1Clear(): 0x26 and 0x27
      21. 15.1.21 InternalTemperature(): 0x28 and 0x29
      22. 15.1.22 CycleCount(): 0x2A and 0x2B
      23. 15.1.23 StateOfCharge(): 0x2C and 0x2D
      24. 15.1.24 StateOfHealth(): 0x2E and 0x2F
      25. 15.1.25 ChargingVoltage(): 0x30 and 0x31
      26. 15.1.26 ChargingCurrent(): 0x32 and 0x33
      27. 15.1.27 PassedCharge(): 0x34 and 0x35
      28. 15.1.28 DOD0(): 0x36 and 0x37
      29. 15.1.29 SelfDischargeCurrent(): 0x38 and 0x39
    2. 15.2 Extended Data Commands
      1. 15.2.1  PackConfiguration(): 0x3A and 0x3B
      2. 15.2.2  DesignCapacity(): 0x3C and 0x3D
      3. 15.2.3  DataFlashClass(): 0x3E
      4. 15.2.4  DataFlashBlock(): 0x3F
      5. 15.2.5  BlockData(): 0x40 Through 0x5F
      6. 15.2.6  BlockDataCheckSum(): 0x60
      7. 15.2.7  BlockDataControl(): 0x61
      8. 15.2.8  DODatEOC(): 0x62 and 0x63
      9. 15.2.9  Qstart(): 0x64 and 0x65
      10. 15.2.10 FastQmax(): 0x66 and 0x67
      11. 15.2.11 Reserved—0x68 to 0x6C
      12. 15.2.12 Reserved—0x6E and 0x6F
      13. 15.2.13 Reserved—0x70 and 0x71
      14. 15.2.14 Reserved—0x72 and 0x73
      15. 15.2.15 AveragePower(): 0x76 and 0x77
      16. 15.2.16 AN_COUNTER: 0x79
      17. 15.2.17 AN_CURRENT_LSB: 0x7A
      18. 15.2.18 AN_CURRENT_MSB: 0x7B
      19. 15.2.19 AN_VCELL_LSB: 0x7C
      20. 15.2.20 AN_VCELL_MSB: 0x7D
      21. 15.2.21 AN_TEMP_LSB: 0x7E
      22. 15.2.22 AN_TEMP_MSB: 0x7F
  17. 16Data Flash Summary
    1. 16.1 Introduction
    2. 16.2 Data Flash Interface
      1. 16.2.1 Accessing the Data Flash
      2. 16.2.2 Access Modes
      3. 16.2.3 Sealing or Unsealing Data Flash
    3. 16.3 Data Flash Summary Tables
  18. 17Factory Calibration
    1. 17.1  General I2C Command Information
    2. 17.2  Calibration
      1. 17.2.1 Method
      2. 17.2.2 Sequence
    3. 17.3  Enter CALIBRATION Mode
    4. 17.4  Exit CALIBRATION Mode
    5. 17.5  CC Offset
    6. 17.6  Board Offset
    7. 17.7  Obtain Raw Calibration Data
    8. 17.8  Current Calibration
    9. 17.9  Voltage Calibration
    10. 17.10 Temperature Calibration
    11. 17.11 Floating Point Conversion
  19. 18Updating the BQ27542-G1 Firmware
    1. 18.1 Data Flash Stream (.DFFS)/BMS Data Flash Stream (.BQFS) Files
    2. 18.2 Write Command
    3. 18.3 Read and Compare Command
    4. 18.4 Wait Command
    5. 18.5 Firmware Updating Flow
    6. 18.6 Debugging BQFS Reader and Programmer
    7. 18.7 Creating a BQFS and DFFS Containing User-Specific DFI
  20. 19Impedance Track Gauge Configuration
    1. 19.1 Introduction
    2. 19.2 Determining ChemID
    3. 19.3 Learning Cycle
    4. 19.4 Common Problems Seen During the Learning Cycle
    5. 19.5 Test Gauge and Optimize
    6. 19.6 Finalize Golden File
    7. 19.7 Program and Test the PCB
  21. 20Revision History

6.3 Current/Power Profiles

For better accuracy and performance, the fuel gauge can be configured with the system or application loading conditions. This helps the gauge to better adapt the algorithm based on the use case.

When a system load is applied, the impedance of the cell is calculated from the OCV, the measured voltage under load, and the discharge current or power as configured in the Load Select parameter. Load Select defines the type of power or current model to be used to compute load-compensated capacity in the Impedance Track algorithm.

For simulations during RELAXATION, CHARGE, and at the start of DISCHARGE (since a new average has not been gathered), it would use data flash values for simulations. Once the discharge lasts 500 seconds, the gauge re-simulates using the new running average. Thereafter, during discharge, it uses the continuous running average for any subsequent simulations. Re-simulations can also be triggered by a temperature change, which can cause an updated simulation to occur earlier than 500 seconds into a discharge. In this case, this simulation would use the present running average.

The Load Mode parameter extends this further by supporting the same options with respect to power instead of current. Load Mode selects either the constant-current or constant-power model for the Impedance Track algorithm as used in Load Select. When Load Mode is 0, the constant current model is used (default). When Load Mode is 1, the constant-power model is used. The CONTROL_STATUS [LDMD] bit reflects the status of Load Mode.

If Load Mode = 0 (constant-current model), then the options presented in Table 7-5.

Table 6-5 Constant-Current Model Used When SHUTDOWN State = 0
Load Select ValueCurrent Model Used
0Average discharge current from previous cycle: There is an internal register that records the average discharge current through each entire discharge cycle. The previous average is stored in this register.
1 (default)Present average discharge current: This is the average discharge current from the beginning of this discharge cycle until present time.
2Average current: based off the AverageCurrent()
3Current: based off of a low-pass-filtered version of AverageCurrent() (τ = 14 s)
4Design capacity/5: C Rate based off of Design Capacity /5 or a C/5 rate in mA
5Use the value specified by AtRate()
6Use the value in User_Rate-mA. This gives a completely user-configurable method.

If SHUTDOWN state = 1 (constant-power model) then the following options are available:

Table 6-6 Constant-Power Model Used When SHUTDOWN State = 1
Load Select ValuePower Model Used
0Average discharge power from previous cycle: There is an internal register that records the average discharge power through each entire discharge cycle. The previous average is stored in this register.
1Present average discharge power: This is the average discharge power from the beginning of this discharge cycle until present time.
2Average current × voltage: based off the AverageCurrent() and Voltage().
3Current × voltage: based off of a low-pass-filtered version of AverageCurrent() (τ = 14 s) and Voltage()
4Design energy/5: C Rate based off of Design Energy /5 or a C/5 rate in mW or cW
5Use the value specified by AtRate()
6Use the value in User_Rate-Pwr. This gives a completely user-configurable method.

The fuel gauge logs the AverageCurrent() averaged from the beginning to the end of each discharge. It stores this average current from the previous discharge period in Avg I Last Run provided that the previous discharge lasted at least 500 seconds.

Note:

It is recommended that users set Avg I Last Run to typical values for their system to correctly initialize predictions.

The fuel gauge logs the power averaged from the beginning to the end of each discharge. It stores this average power from the previous discharge period in Avg P Last Run provided the previous discharge lasted at least 500 seconds. To get a correct average power reading, the fuel gauge continuously multiplies instantaneous current with Voltage() to get power. It then logs this data to derive the average power.

Note:

It is recommended that users set Avg P Last Run to typical values for their system to correctly initialize predictions.

In situations wherein the available load options do not match the application, custom current or power profiles can also be provided to the gauge. User Rate-mA can be used to indicate a current load that the algorithm will use for the RemainingCapacity() computation in the Impedance Track algorithm.

Note:

This parameter is used only when Load Select = 6 and SHUTDOWN state = 0. An example application that requires this register is one that has increased predefined current at the end of discharge. With this application, it is logical to adjust the rate compensation to this period because the IR drop during this end period is affected the moment Terminate Voltage is reached.

User Rate-Pwr can be used to indicate a power load that the algorithm will use for the RemainingCapacity() computation in the Impedance Track algorithm.

Note:

This parameter is used only when Load Select = 6 and SHUTDOWN state = 1. An example application that requires this register is one that has increased predefined power at the end of discharge. With this application, it is logical to adjust the rate compensation to this period because the IR drop during this end period is affected the moment Terminate Voltage is reached. The actual unit of this parameter is dependent on Design Energy Scale.

The gauge also provides maximum and minimum limits for current/power used in IT simulations. These are the Max Sim Rate and Min Sim Rate parameters. They are a function of Design Capacity or Design Energy.

Table 6-7 SHUTDOWN state Limits
SHUTDOWN stateLimit
0–Design Capacity/Max Sim Rate ≤ Simulation Current ≤ –Design Capacity/Min Sim Rate
1–Design Energy/Max Sim Rate ≤ Simulation Power ≤ –Design Energy/Min Sim Rate

In situations where a controlled shutdown after 0% RemainingCapacity() is reached, the Reserve Cap-mAh can be used that determines how much actual remaining capacity exists after reaching 0% RemainingCapacity(), before Terminate Voltage is reached when SHUTDOWN state = 0 is selected. A loaded rate or no-load rate of compensation can be selected for Reserve Cap by setting the [RESCAP] bit in the Pack Configuration data flash register. This is a specialized function to allow time for a controlled shutdown after 0 RemainingCapacity() is reached.

The voltage must dip below Terminate Voltage for at least this many seconds before RemainingCapacity() and StateOfCharge() will be forced to 0.

Subclass IDSubclassOffsetNameData TypeValueUnit
MinMaxDefault
80IT Cfg0Load SelectU1061Number
1SHUTDOWN stateU1011Number
64Terminate VoltageI2280037003000mV
73User Rate-mAI20327670mA
75User Rate-PwrI20327670cW
77Reserve Cap-mAhI20145000mAh
88Max Sim RateU102551HourRate
89Min Sim RateU1025520HourRate
118TermV Valid tU102552s
82State5Avg I Last RunI2–327680–299mA
7Avg P Last RunI2–327680–1131mA