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

9.2.2.3 Output Capacitor

The output capacitor also should have enough ripple current rating to absorb output switching ripple current. The output capacitor RMS current ICOUT is given as:

Equation 15. BQ24650 EQ14_ICOUT_lusa75.gif

The output capacitor voltage ripple can be calculated in Equation 16:

Equation 16. BQ24650 EQ15_DVO_lusa75.gif

At certain input/output voltages and switching frequencies, the voltage ripple can be reduced by increasing the output filter inductor and capacitor values.

The BQ24650 has an internal loop compensator. To achieve good loop stability, the resonant frequency of the output inductor and output capacitor must be designed between 12 kHz and 17 kHz. The preferred ceramic capacitor has a 35 V or higher rating, X7R or X5R.

Ceramic capacitors show a de-bias effect. This effect reduces the effective capacitance when a DC-bias voltage is applied across a ceramic capacitor, as on the output capacitor of a charger. The effect may lead to a significant capacitance drop, especially for high voltages and small capacitor packages. See the manufacturer’s datasheet about performance with a DC bias voltage applied. It may be necessary to choose a higher voltage rating or nominal capacitance value to achieve the required value at the operating point.