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

Detailed Design Procedure

The recommended L1 = 22 µH, CBYP = 0.01 µF and low leakage CREF = 10 nF are selected. In order to ensure the fastest recovery of the harvester output voltage to the MPPT level following power extraction, the minimum recommended CIN = 4.7 µF is selected. Because no large system load transients are expected and to ensure fast charge time during cold start, the minimum recommended CSTOR = 4.7 µF. To stop charging when the IC junction temperature is above 65°C, the OT_PROG pin is tied to ground.

  • With VBAT_UV < VBAT_OV ≤ 5.5 V, to size the VBAT_OV resistors, first choose RSUMOV = ROV1 + ROV2 = 10 MΩ then solve Equation 3 for
  • Equation 10. BQ25504 Eq10_Rov1_slusah0.gif
  • ROV2 = RSUMOV - ROV1 = 10 MΩ - 5.95 MΩ = 4.05 MΩ → 4.02 MΩ resulting in VBAT_OV = 3.15 V
  • To size the VBAT_UV resistors, first choose RSUMUV = RUV1 + RUV2 = 10 MΩ then solve Equation 2 for
  • Equation 11. BQ25504 Eq11_RUV1_slusah0.gif
  • RUV2 = RSUMUV - RUV1 = 10 MΩ - 5.60 MΩ = 4.4 MΩ → 4.42 MΩ closest 1% resistor resulting in
    VBAT_UV = 2.2 V.
  • With VBAT_OV ≥ VBAT_OK_HYST > VBAT_OK ≥ VBAT_UV, to size the VBAT_OK and VBAT_OK_HYST resistors,
    first choose RSUMOK = ROK1 + ROK2 + ROK3 = 10 MΩ then solve Equation 4 and Equation 5 for
  • Equation 12. BQ25504 Eq12_ROK1_slusah0.gif
    Equation 13. BQ25504 Eq13_ROK2_slusah0.gif
  • ROK3 = RSUMOK - ROK1 - ROK2 = 10 MΩ - 4.42 MΩ - 4.22 MΩ = 1.36 MΩ → 1.43 MΩ to give
    VBAT_OK = 2.44 V and VBAT_OK_HYST = 2.85 V.
  • Keeping in mind that VREF_SAMP stores the MPP voltage for the harvester, first choose RSUMOC = ROC1 + ROC2 = 20 MΩ then solve Equation 1 for
  • Equation 14. BQ25504 Eq14_ROC1_slusah0.gif
    Equation 15. BQ25504 Eq15_ROC2_slusah0.gif
  • SLURAQ1 provides help on sizing and selecting the resistors.