SLUSA75B July   2010  – January 2020 BQ24650

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin 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 Electrical Characteristics
    6. 7.6 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  Battery Voltage Regulation
      2. 8.3.2  Input Voltage Regulation
      3. 8.3.3  Battery Current Regulation
      4. 8.3.4  Battery Precharge
      5. 8.3.5  Charge Termination and Recharge
      6. 8.3.6  Power Up
      7. 8.3.7  Enable and Disable Charging
      8. 8.3.8  Automatic Internal Soft-Start Charger Current
      9. 8.3.9  Converter Operation
      10. 8.3.10 Synchronous and Non-Synchronous Operation
      11. 8.3.11 Cycle-by-Cycle Charge Undercurrent
      12. 8.3.12 Input Overvoltage Protection (ACOV)
      13. 8.3.13 Input Undervoltage Lockout (UVLO)
      14. 8.3.14 Battery Overvoltage Protection
      15. 8.3.15 Cycle-by-Cycle Charge Overcurrent Protection
      16. 8.3.16 Thermal Shutdown Protection
      17. 8.3.17 Temperature Qualification
      18. 8.3.18 Charge Enable
      19. 8.3.19 Inductor, Capacitor, and Sense Resistor Selection Guidelines
      20. 8.3.20 Charge Status Outputs
      21. 8.3.21 Battery Detection
        1. 8.3.21.1 Example
    4. 8.4 Device Functional Modes
      1. 8.4.1 Converter Operation
      2. 8.4.2 Synchronous and Non-Synchronous Operation
  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 Inductor Selection
        2. 9.2.2.2 Input Capacitor
        3. 9.2.2.3 Output Capacitor
        4. 9.2.2.4 Power MOSFETs Selection
        5. 9.2.2.5 Input Filter Design
        6. 9.2.2.6 MPPT Temperature Compensation
      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 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.2 Input Capacitor

The input capacitor should have enough ripple current rating to absorb input switching ripple current. The worst-case RMS ripple current is half of the charging current when duty cycle is 0.5. If the converter does not operate at 50% duty cycle, then the worst case capacitor RMS current ICIN occurs where the duty cycle is closest to 50% and can be estimated by Equation 14:

Equation 14. BQ24650 EQ13_ICIN_lusa75.gif

A low ESR ceramic capacitor such as X7R or X5R is preferred for the input decoupling capacitor and must be placed as close as possible to the drain of the high-side MOSFET and source of the low-side MOSFET. The voltage rating of the capacitor must be higher than the normal input voltage level. A 25-V rating or higher capacitor is preferred for a 20-V input voltage. A 20-μF capacitance is suggested for a typical 3-A to 4-A charging current.