SLUUCD5 January   2023 BQ27427

 

  1.   Read This First
    1. 1.1 Notational conventions used in this document:
    2. 1.2 Trademarks
    3. 1.3 Glossary
  2. 1General Description
  3. 2Functional Description
    1. 2.1 Fuel Gauging
    2. 2.2 Temperature Measurement
    3. 2.3 Current Measurement
    4. 2.4 Operating Modes
      1. 2.4.1 SHUTDOWN Mode
      2. 2.4.2 POR and INITIALIZATION Modes
      3. 2.4.3 CONFIG UPDATE Mode
      4. 2.4.4 NORMAL Mode
      5. 2.4.5 SLEEP Mode
    5. 2.5 Pin Descriptions
      1. 2.5.1 GPOUT Pin
      2. 2.5.2 Battery Detection (BIN)
  4. 3Communications
    1. 3.1 I2C Interface
    2. 3.2 I2C Time Out
    3. 3.3 I2C Command Waiting Time
    4. 3.4 I2C Clock Stretching
  5. 4Application Examples
    1. 4.1 Data Memory Parameter Update Example
    2. 4.2 Chemistry Profile Change Example
  6. 5Standard Commands
    1. 5.1  Control(): 0x00 and 0x01
      1. 5.1.1  CONTROL_STATUS: 0x0000
      2. 5.1.2  DEVICE_TYPE: 0x0001
      3. 5.1.3  FW_VERSION: 0x0002
      4. 5.1.4  DM_CODE: 0x0004
      5. 5.1.5  PREV_MACWRITE: 0x0007
      6. 5.1.6  CHEM_ID: 0x0008
      7. 5.1.7  BAT_INSERT: 0x000C
      8. 5.1.8  BAT_REMOVE: 0x000D
      9. 5.1.9  SET_CFGUPDATE: 0x0013
      10. 5.1.10 SMOOTH_SYNC: 0x0019
      11. 5.1.11 SHUTDOWN_ENABLE: 0x001B
      12. 5.1.12 SHUTDOWN: 0x001C
      13. 5.1.13 SEALED: 0x0020
      14. 5.1.14 PULSE_SOC_INT: 0x0023
      15. 5.1.15 CHEM_A:/B/C 0x0030/0x0031/0x0032
      16. 5.1.16 RESET: 0x0041
      17. 5.1.17 SOFT_RESET: 0x0042
    2. 5.2  Temperature(): 0x02 and 0x03
    3. 5.3  Voltage(): 0x04 and 0x05
    4. 5.4  Flags(): 0x06 and 0x07
    5. 5.5  NominalAvailableCapacity(): 0x08 and 0x09
    6. 5.6  FullAvailableCapacity(): 0x0A and 0x0B
    7. 5.7  RemainingCapacity(): 0x0C and 0x0D
    8. 5.8  FullChargeCapacity(): 0x0E and 0x0F
    9. 5.9  AverageCurrent(): 0x10 and 0x11
    10. 5.10 AveragePower(): 0x18 and 0x19
    11. 5.11 StateOfCharge(): 0x1C and 0x1D
    12. 5.12 InternalTemperature(): 0x1E and 0x1F
    13. 5.13 RemainingCapacityUnfiltered(): 0x28 and 0x29
    14. 5.14 RemainingCapacityFiltered(): 0x2A and 0x2B
    15. 5.15 FullChargeCapacityUnfiltered(): 0x2C and 0x2D
    16. 5.16 FullChargeCapacityFiltered(): 0x2E and 0x2F
    17. 5.17 StateOfChargeUnfiltered(): 0x30 and 0x31
  7. 6Extended Data Commands
    1. 6.1 DataClass(): 0x3E
    2. 6.2 DataBlock(): 0x3F
    3. 6.3 BlockData(): 0x40 Through 0x5F
    4. 6.4 BlockDataChecksum(): 0x60
    5. 6.5 BlockDataControl(): 0x61
    6. 6.6 Reserved—0x62 Through 0x7F
  8. 7Data Memory
    1. 7.1 Data Memory Interface
      1. 7.1.1 Accessing the Data Memory
      2. 7.1.2 Access Modes
      3. 7.1.3 SEALING and UNSEALING Data Memory Access
    2. 7.2 Data Types Summary
    3. 7.3 Data Flash Summary
    4. 7.4 Data Memory Parameter Descriptions
      1. 7.4.1 Configuration Class
        1. 7.4.1.1 Safety Subclass
          1. 7.4.1.1.1 Over-Temperature Threshold, Under-Temperature Threshold, Temperature Hysteresis
        2. 7.4.1.2 Charge Termination Subclass
          1. 7.4.1.2.1 Terminate Charge Alarm Set %, Terminate Charge Alarm Clear %
          2. 7.4.1.2.2 Full Charge Set %, Full Charge Clear %
          3. 7.4.1.2.3 DOD at EOC Delta Temperature
        3. 7.4.1.3 Discharge Subclass
          1. 7.4.1.3.1 State-of-Charge 1 Set Threshold, State-of-Charge 1 Clear Threshold
          2. 7.4.1.3.2 State-of-Charge Final Set Threshold, State-of-Charge Final Clear Threshold
        4. 7.4.1.4 Registers
          1. 7.4.1.4.1 Operation Configuration (OpConfig) Register
          2. 7.4.1.4.2 Operation Configuration B (OpConfigB) Register
          3. 7.4.1.4.3 Operation Configuration C (OpConfigC) Register
          4. 7.4.1.4.4 Operation Configuration D (OpConfigD) Register
      2. 7.4.2 Gas (Fuel) Gauging Class
        1. 7.4.2.1 IT Cfg Subclass
          1. 7.4.2.1.1  OCV Wait Time
          2. 7.4.2.1.2  Ra Filter
          3. 7.4.2.1.3  Resistance Update Voltage Drop
          4. 7.4.2.1.4  Samples to Wake
          5. 7.4.2.1.5  Qmax Max Time
          6. 7.4.2.1.6  Fast Qmax Start DOD%, Fast Qmax Start Voltage Delta, Fast Qmax Current Threshold
          7. 7.4.2.1.7  Fast Qmax End DOD%, Fast Qmax Minimum Data Points
          8. 7.4.2.1.8  Maximum Qmax Change
          9. 7.4.2.1.9  Qmax Maximum Delta %
          10. 7.4.2.1.10 Maximum % Default Qmax
          11. 7.4.2.1.11 Qmax Filter
          12. 7.4.2.1.12 Simulation ResRelax Time (ResRelax Time)
          13. 7.4.2.1.13 User-Defined Rate-Current
          14. 7.4.2.1.14 User-Defined Rate-Power
          15. 7.4.2.1.15 Maximum Simulation Rate, Minimum Simulation Rate
          16. 7.4.2.1.16 Ra Max Delta
          17. 7.4.2.1.17 Minimum Delta Voltage, Maximum Delta Voltage
          18. 7.4.2.1.18 DeltaV Maximum Delta Voltage
          19. 7.4.2.1.19 Terminate Voltage Valid Time
          20. 7.4.2.1.20 Trace Resistance
          21. 7.4.2.1.21 Downstream Resistance
          22. 7.4.2.1.22 Predict Ambient Time
          23. 7.4.2.1.23 Design Energy Scale
          24. 7.4.2.1.24 Fast Scale Load Select
          25. 7.4.2.1.25 Chg DOD Correction Start SOC
          26. 7.4.2.1.26 Chg DOD Correction Taper Ratio
        2. 7.4.2.2 Current Thresholds Subclass
          1. 7.4.2.2.1 Discharge and Charge Detection Threshold, Quit Current and Relax Time, Discharge and Charge Relax Time
          2. 7.4.2.2.2 Max IR Correct
        3. 7.4.2.3 State Subclass
          1. 7.4.2.3.1  Qmax Cell 0
          2. 7.4.2.3.2  Update Status
          3. 7.4.2.3.3  Reserve Capacity (mAh)
          4. 7.4.2.3.4  Load Select, Load Mode
          5. 7.4.2.3.5  Design Capacity, Design Energy, Default Design Capacity
          6. 7.4.2.3.6  Terminate Voltage
          7. 7.4.2.3.7  Thermal Rise Factor (T Rise)
          8. 7.4.2.3.8  Thermal Time Constant (T Time Constant)
          9. 7.4.2.3.9  SOC Interrupt Delta
          10. 7.4.2.3.10 Taper Rate, Taper Voltage
          11. 7.4.2.3.11 Sleep Current
          12. 7.4.2.3.12 Voltage at Charge Termination
          13. 7.4.2.3.13 Average Current Last Run
          14. 7.4.2.3.14 Average Power Last Run
          15. 7.4.2.3.15 Delta Voltage
      3. 7.4.3 Ra Table Class
        1. 7.4.3.1 R_a RAM Subclass
      4. 7.4.4 Chemistry Class
        1. 7.4.4.1 Chem Data Subclass
          1. 7.4.4.1.1 Q Invalid Max V and Q Invalid Min V
          2. 7.4.4.1.2 V at Chg Term
          3. 7.4.4.1.3 Taper Voltage
      5. 7.4.5 Calibration Class
        1. 7.4.5.1 Data Subclass
          1. 7.4.5.1.1 Board Offset
          2. 7.4.5.1.2 Internal Temperature Offset and External Temperature Offset
          3. 7.4.5.1.3 Pack Voltage Offset
          4. 7.4.5.1.4 Ext a Coef and Ext b Coef
        2. 7.4.5.2 CC Cal Subclass
          1. 7.4.5.2.1 CC Cal Temp
        3. 7.4.5.3 Current Subclass
          1. 7.4.5.3.1 Deadband
      6. 7.4.6 Security Class
        1. 7.4.6.1 Codes Subclass
          1. 7.4.6.1.1 Sealed to Unsealed
  9. 8Updating BQ27427 Configuration Parameters
    1. 8.1 Gauge Mode FlashStream (gm.fs) Files
    2. 8.2 Write Command
    3. 8.3 Read and Compare Command
    4. 8.4 Wait Command
    5. 8.5 CONFIG UPDATE Mode
  10. 9Revision History

2.1 Fuel Gauging

The BQ27427 battery fuel gauge measures the cell voltage, temperature, and current to determine battery SOC. The fuel gauge monitors the charging and discharging of the battery by sensing the voltage across an integrated sense resistor (7 mΩ, typical) between the BAT and SRX pins. By integrating the charge passing through the battery, the battery SOC is adjusted during the charging or discharging of the battery.

The total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. When an application load is applied, the impedance of the cell is measured by comparing the OCV obtained from a predefined function for the present SOC with the measured voltage under load. Measurements of OCV and charge integration determine chemical SOC and chemical capacity (Qmax). The initial value for Qmax is defined by Design Capacity and should match the cell manufacturers' data sheet. The fuel gauge acquires and updates the battery-impedance profile during normal battery usage. The impedance profile along with SOC and the Qmax value are used to determine FullChargeCapacity() and StateOfCharge(), specifically for the present load and temperature. FullChargeCapacity() is reported as capacity available from a fully-charged battery under the present load and temperature until Voltage() reaches the Terminate Voltage. NominalAvailableCapacity() and FullAvailableCapacity() are the uncompensated (no or light load) versions of RemainingCapacity() and FullChargeCapacity(), respectively.

The fuel gauge has two flags, [SOC1] and [SOCF], accessed by the Flags() command that warn when the battery SOC has fallen to critical levels. When StateOfCharge() falls below the first capacity threshold, as specified in SOC1 Set Threshold, the [SOC1] (state-of-charge initial) flag is set. The flag is cleared once StateOfCharge() rises above SOC1 Set Threshold. All units are in %.

When StateOfCharge() falls below the second capacity threshold, SOCF Set Threshold, the [SOCF] (state-of-charge final) flag is set, serving as a final discharge warning. If SOCF Set Threshold = –1, the flag is inoperative during discharge. Similarly, when StateOfCharge() rises above SOCF Clear Threshold and the [SOCF] flag has already been set, the [SOCF] flag is cleared. All units are in %.