SLUSBJ3F August   2013  – March 2019

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Charger Efficiency
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Maximum Power Point Tracking
      2. 7.3.2 Battery Undervoltage Protection
      3. 7.3.3 Battery Overvoltage Protection
      4. 7.3.4 Battery Voltage in Operating Range (VBAT_OK Output)
      5. 7.3.5 Push-Pull Multiplexer Drivers
      6. 7.3.6 Nano-Power Management and Efficiency
    4. 7.4 Device Functional Modes
      1. 7.4.1 Main Boost Charger Disabled (Ship Mode) - (VSTOR > VSTOR_CHGEN and EN = HIGH)
      2. 7.4.2 Cold-Start Operation (VSTOR < VSTOR_CHGEN, VIN_DC > VIN(CS) and PIN > PIN(CS))
      3. 7.4.3 Main Boost Charger Enabled (VSTOR > VSTOR_CHGEN, VIN_DC > VIN(DC) and EN = LOW )
      4. 7.4.4 Thermal Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Energy Harvester Selection
      2. 8.1.2 Storage Element Selection
      3. 8.1.3 Inductor Selection
      4. 8.1.4 Capacitor Selection
        1. 8.1.4.1 VREF_SAMP Capacitance
        2. 8.1.4.2 VIN_DC Capacitance
        3. 8.1.4.3 VSTOR Capacitance
        4. 8.1.4.4 Additional Capacitance on VSTOR or VBAT_SEC
    2. 8.2 Typical Applications
      1. 8.2.1 Solar Application Circuit
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Performance Plots
      2. 8.2.2 TEG Application Circuit
      3. 8.2.3 Design Requirements
        1. 8.2.3.1 Detailed Design Procedure
        2. 8.2.3.2 Application Performance Plots
      4. 8.2.4 Piezoelectric Application Circuit
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
        3. 8.2.4.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Zip Files
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.4.4 Thermal Shutdown

Rechargeable Li-ion batteries need protection from damage due to operation at elevated temperatures. The application should provide this battery protection and ensure that the ambient temperature is never elevated greater than the expected operational range of 85°C.

The bq25505 uses an integrated temperature sensor to monitor the junction temperature of the device. The temperature threshold for thermal protection is set to 125°C. Once the temperature threshold is exceeded, the boost charger is disabled and charging ceases. Once the temperature of the device drops below this threshold, the boost charger and buck converter resumes operation. To avoid unstable operation near the overtemp threshold, a built-in hysteresis of approximately 5°C has been implemented. Care should be taken to not over discharge the battery in this condition since the boost charger is disabled. However, if the supply voltage drops to the VBAT_UV setting, then the switch between VBAT_SEC and VSTOR will open and protect the battery even if the device is in thermal shutdown.