SLUSA91C October   2010  – October 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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  Electrical Characteristics: Supply Current
    6. 6.6  Power-On Reset (POR)
    7. 6.7  Wake From Sleep
    8. 6.8  RBI RAM Backup
    9. 6.9  3.3-V Regulator
    10. 6.10 2.5-V Regulator
    11. 6.11 PRES, SMBD, SMBC
    12. 6.12 CHG, DSG FET Drive
    13. 6.13 PCHG FET Drive
    14. 6.14 FUSE
    15. 6.15 Coulomb Counter
    16. 6.16 VC1, VC2, VC3, VC4
    17. 6.17 TS1, TS2
    18. 6.18 Internal Temperature Sensor
    19. 6.19 Internal Thermal Shutdown
    20. 6.20 High-Frequency Oscillator
    21. 6.21 Low-Frequency Oscillator
    22. 6.22 Internal Voltage Reference
    23. 6.23 Flash
    24. 6.24 OCD Current Protection
    25. 6.25 SCD1 Current Protection
    26. 6.26 SCD2 Current Protection
    27. 6.27 SCC Current Protection
    28. 6.28 SBS Timing Requirements
    29. 6.29 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Battery Parameter Measurements
      1. 7.1.1 Charge and Discharge Counting
      2. 7.1.2 Voltage
      3. 7.1.3 Current
      4. 7.1.4 Auto Calibration
      5. 7.1.5 Temperature
      6. 7.1.6 Communications
        1. 7.1.6.1 SMBus On and Off State
        2. 7.1.6.2 SBS Commands
  8. 8 Detailed Description
    1. 8.1 Overview
      1. 8.1.1 Configuration
        1. 8.1.1.1 Oscillator Function
        2. 8.1.1.2 System Present Operation
        3. 8.1.1.3 2-, 3-, or 4-Cell Configuration
        4. 8.1.1.4 Cell Balancing
          1. 8.1.1.4.1 Internal Cell Balancing
          2. 8.1.1.4.2 External Cell Balancing
    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 Lifetime Data Logging Features
      6. 8.3.6 Authentication
    4. 8.4 Device Functional Modes
  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 High-Current Path
          1. 9.2.2.1.1 Protection FETs
          2. 9.2.2.1.2 Chemical Fuse
          3. 9.2.2.1.3 Lithium-Ion Cell Connections
          4. 9.2.2.1.4 Sense Resistor
          5. 9.2.2.1.5 ESD Mitigation
        2. 9.2.2.2 Gas Gauge Circuit
          1. 9.2.2.2.1 Differential Low-Pass Filter
          2. 9.2.2.2.2 Power Supply Decoupling and RBI
          3. 9.2.2.2.3 System Present
          4. 9.2.2.2.4 SMBus Communication
          5. 9.2.2.2.5 FUSE Circuitry
          6. 9.2.2.2.6 PFIN Detection
        3. 9.2.2.3 Secondary-Current Protection
          1. 9.2.2.3.1 Cell and Battery Inputs
          2. 9.2.2.3.2 External Cell Balancing
          3. 9.2.2.3.3 PACK and FET Control
          4. 9.2.2.3.4 Regulator Output
          5. 9.2.2.3.5 Temperature Output
        4. 9.2.2.4 Secondary-Overvoltage Protection
          1. 9.2.2.4.1 Cell Inputs
          2. 9.2.2.4.2 Time-Delay Capacitor
      3. 9.2.3 Application Curves
    3. 9.3 System Example
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

7 Parameter Measurement Information

7.1 Battery Parameter Measurements

7.1.1 Charge and Discharge Counting

The bq3055 uses an integrating delta-sigma analog-to-digital converter (ADC) for current measurement, and a second delta-sigma ADC for individual cell and battery voltage and temperature measurement.

The integrating delta-sigma ADC measures the charge/discharge flow of the battery by measuring the voltage drop across a small-value sense resistor between the SR1 and SR2 pins. The integrating ADC measures bipolar signals from –0.25 V to 0.25 V. The bq3055 detects charge activity when VSR = V(SRP) – V(SRN) is positive, and discharge activity when VSR = V(SRP) – V(SRN) is negative. The bq3055 continuously integrates the signal over time, using an internal counter. The fundamental rate of the counter is 0.65 nVh.

7.1.2 Voltage

The bq3055 updates the individual series cell voltages at 0.25-second intervals. The internal ADC of the bq3055 measures the voltage, and scales and calibrates it appropriately. This data is also used to calculate the impedance of the cell for the CEDV gas-gauging.

7.1.3 Current

The bq3055 uses the SRP and SRN inputs to measure and calculate the battery charge and discharge current using a 5-mΩ to 20-mΩ typ. sense resistor.

7.1.4 Auto Calibration

The bq3055 provides an auto-calibration feature to cancel the voltage offset error across SRN and SRP for maximum charge measurement accuracy. The bq3055 performs auto-calibration when the SMBus lines stay low continuously for a minimum of 5 s.

7.1.5 Temperature

The bq3055 has an internal temperature sensor and inputs for two external temperature sensors. All three temperature sensor options are individually enabled and configured for cell or FET temperature. Two configurable thermistor models are provided to allow the monitoring of cell temperature in addition to FET temperature, which may be of a higher temperature type.

7.1.6 Communications

The bq3055 uses SMBus v1.1 with Master Mode and packet error checking (PEC) options per the SBS specification.

7.1.6.1 SMBus On and Off State

The bq3055 detects an SMBus off state when SMBC and SMBD are low for two or more seconds. Clearing this state requires that either SMBC or SMBD transition high. The communication bus will resume activity within 1 ms.

7.1.6.2 SBS Commands

See the bq3055 Technical Reference Manual (SLUU440) for further details.