SLUSA92D January   2011  – May 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  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  Supply Current
    6. 7.6  Power-On Reset (POR)
    7. 7.7  WAKE FROM SLEEP
    8. 7.8  RBI RAM Backup
    9. 7.9  3.3-V Regulator
    10. 7.10 2.5-V Regulator
    11. 7.11 DISP, PRES, SMBD, SMBC
    12. 7.12 CHG, DSG FET Drive
    13. 7.13 Internal Precharge Limiting
    14. 7.14 GPOD
    15. 7.15 FUSE
    16. 7.16 LED5, LED4, LED3, LED2, LED1
    17. 7.17 Coulomb Counter
    18. 7.18 VC1, VC2, VC3, VC4
    19. 7.19 TS1, TS2
    20. 7.20 Internal Temperature Sensor
    21. 7.21 Internal Thermal Shutdown
    22. 7.22 High Frequency Oscillator
    23. 7.23 Low Frequency Oscillator
    24. 7.24 Internal Voltage Reference
    25. 7.25 Flash
    26. 7.26 OCD Current Protection
    27. 7.27 SCD1 Current Protection
    28. 7.28 SCD2 Current Protection
    29. 7.29 SCC Current Protection
    30. 7.30 SBS Timing Requirements
    31. 7.31 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 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
    5. 8.5 Configuration
      1. 8.5.1 Oscillator Function
      2. 8.5.2 System Present Operation
      3. 8.5.3 2-, 3-, or 4-Cell Configuration
      4. 8.5.4 Cell Balancing
        1. 8.5.4.1 Internal Cell Balancing
        2. 8.5.4.2 External Cell Balancing
    6. 8.6 Battery Parameter Measurements
      1. 8.6.1 Charge and Discharge Counting
      2. 8.6.2 Voltage
      3. 8.6.3 Current
      4. 8.6.4 Auto Calibration
      5. 8.6.5 Temperature
      6. 8.6.6 Communications
        1. 8.6.6.1 SMBus On and Off State
        2. 8.6.6.2 SBS Commands
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      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
          6. 9.2.2.3.6 LEDs
          7. 9.2.2.3.7 Safety PTC Thermistor
        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
  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

11 Layout

11.1 Layout Guidelines

The predominant layout concern for the bq3050 is related to the coulomb counter measurement. The external components and PCB layout surrounding the SRP and SRN pins should be carefully considered.

11.2 Layout Example

As shown in Figure 26, a differential filter must precede the current sense inputs of the gas gauge. This filter eliminates the effect of unwanted digital noise, which can cause offset in the measured current. Even the best differential amplifier has less common-mode rejection at high frequencies. Without a filter, the amplifier input stage may rectify a strong RF signal, which then may appear as a dc-offset error.

Five percent tolerance of the components is adequate, because capacitor C15 shunts C12 and C13 and reduces AC common mode arising from a component mismatch. It is important to locate C15 as close as possible to the gas gauge pins. The other components also must be relatively close to the IC. The ground connection of C12 and C13 must be close to the IC. It is also proven to reduce offset and noise error by maintaining a symmetrical placement pattern and adding ground shielding for the differential filter network.

bq3050 SenseResistorLayout_3050.pngFigure 26. Layout Example