SLVSGS9E March   2023  – June 2024 TPS61299

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 System Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Boost Control Operation
      2. 7.3.2  Version Detection
      3. 7.3.3  Under-voltage Lockout
      4. 7.3.4  Switching Frequency
      5. 7.3.5  Input Current Limit
      6. 7.3.6  Enable and Disable
      7. 7.3.7  Soft-Start Timing
      8. 7.3.8  Down Mode
      9. 7.3.9  Pass-Through Operation
      10. 7.3.10 Output Short-to-Ground Protection
      11. 7.3.11 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Fast Load Transient Mode and Normal Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application-Li-ion Battery to 5V Boost Converter Under Fast Mode
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Maximum Output Current
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Input Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Typical Application-Li-ion Battery to 5V Boost Converter Under Normal Mode
      1. 8.3.1 Design Requirements
      2. 8.3.2 Application Curves
    4. 8.4 TPS61299xA Typical Application-Li-ion Battery to 5V Boost Converter Under Normal Mode
      1. 8.4.1 Design Requirements
      2. 8.4.2 Application Curves
    5. 8.5 Power Supply Recommendations
    6. 8.6 Layout
      1. 8.6.1 Layout Guidelines
      2. 8.6.2 Layout Example
    7. 8.7 Thermal Information
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.2.3 Output Capacitor Selection

The output capacitor is mainly selected to meet the requirements for output ripple and loop stability. The ripple voltage is related to capacitor capacitance and its equivalent series resistance (ESR). Assuming a ceramic capacitor with zero ESR, the minimum capacitance needed for a given ripple voltage can be calculated by Equation 3.

Equation 3. TPS61299

where

  • DMAX is the maximum switching duty cycle.
  • VRIPPLE is the peak-to-peak output ripple voltage.
  • IOUT is the maximum output current.
  • fSW is the switching frequency.

The ESR impact on the output ripple must be considered if tantalum or aluminum electrolytic capacitors are used. The output peak-to-peak ripple voltage caused by the ESR of the output capacitors can be calculated by Equation 4.

Equation 4. TPS61299

Take care when evaluating the derating of a ceramic capacitor under DC bias voltage, aging, and AC signal. For example, the DC bias voltage can significantly reduce capacitance. A ceramic capacitor can lose more than 50% of its capacitance at its rated voltage. Therefore, always leave margin on the voltage rating to make sure there is adequate capacitance at the required output voltage. Increasing the output capacitor makes the output ripple voltage smaller in PWM mode.

TI recommends using the X5R or X7R ceramic output capacitor in the range of 4μF to 1000μF effective capacitance. The output capacitor affects the small signal control loop stability of the boost regulator. Effective output capacitance should be no less than 20uF as soon as output current is higher than 1A or the TPS612997, the 1.9A input current limit version device is used. If the output capacitor is below the range, the boost regulator can potentially become unstable.