SLUSAH0F October   2011  – November 2019 BQ25504

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Solar Application Circuit
  4. Revision History
  5. Description (continued)
  6. Pin Configuration and Functions
    1.     Pin Functions
  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 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Maximum Power Point Tracking
      2. 8.3.2 Battery Undervoltage Protection
      3. 8.3.3 Battery Overvoltage Protection
      4. 8.3.4 Battery Voltage in Operating Range (VBAT_OK Output)
      5. 8.3.5 Nano-Power Management and Efficiency
    4. 8.4 Device Functional Modes
      1. 8.4.1 Cold-Start Operation (VSTOR < VSTOR_CHGEN, VIN_DC > VIN(CS) and PIN > PIN(CS))
      2. 8.4.2 Main Boost Charger Enabled (VSTOR > VSTOR_CHGEN, VIN_DC > VIN(DC) and EN = LOW )
      3. 8.4.3 Thermal Shutdown
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Storage Element Selection
      2. 9.1.2 Inductor Selection
      3. 9.1.3 Capacitor Selection
        1. 9.1.3.1 VREF_SAMP Capacitance
        2. 9.1.3.2 VIN_DC Capacitance
        3. 9.1.3.3 VSTOR Capacitance
        4. 9.1.3.4 Additional Capacitance on VSTOR or VBAT
    2. 9.2 Typical Applications
      1. 9.2.1 Solar Application Circuit
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 TEG Application Circuit
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 MPPT Disabled, Low Impedance Source Application Circuit
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Zip Files
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Inductor Selection

The boost charger needs an appropriately sized inductor for proper operation. The inductor's saturation current should be at least 25% higher than the expected peak inductor currents recommended below if system load transients on VSTOR are expected.  Since this device uses hysteretic control, the boost charger is considered naturally stable systems (single order transfer function). 

For the boost charger to operate properly, an inductor of appropriate value must be connected between LBOOST, pin 20, and VIN_DC, pin 2. The boost charger internal control circuitry is designed to control the switching behavior with a nominal inductance of 22 µH ± 20%. The inductor must have a peak current capability of > 300 mA with a low series resistance (DCR) to maintain high efficiency.

A list of inductors recommended for this device is shown in Table 1.

Table 1. Recommended Inductors

Inductance (µH) Dimensions (mm) Part Number Manufacturer(1)
22 4.0x4.0x1.7 LPS4018-223M Coilcraft
22 3.8x3.8x1.65 744031220 Wurth
22 2.8x2.8x2.8 744025220 Wurth
See WHAT? concerning recommended third-party products.