SLVSIF3B February   2025  – August 2026 TPS561300

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Fixed-Frequency PWM Control
      2. 6.3.2  Pulse Frequency Mode
      3. 6.3.3  Error Amplifier
      4. 6.3.4  Slope Compensation and Output Current
      5. 6.3.5  Enable and Adjusting Undervoltage Lockout
      6. 6.3.6  Safe Start-Up into Prebiased Outputs
      7. 6.3.7  Voltage Reference
      8. 6.3.8  Adjusting Output Voltage
      9. 6.3.9  Internal Soft Start
      10. 6.3.10 Bootstrap Voltage (BOOT)
      11. 6.3.11 Overcurrent Protection
        1. 6.3.11.1 High-Side MOSFET Overcurrent Protection
        2. 6.3.11.2 Low-Side MOSFET Overcurrent Protection
      12. 6.3.12 Spread Spectrum
      13. 6.3.13 Output Overvoltage Protection (OVP)
      14. 6.3.14 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Eco-mode Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 TPS561300 5V to 30V Input, 5V Output Converter
      2. 7.2.2 Design Requirements
      3. 7.2.3 Detailed Design Procedure
        1. 7.2.3.1 Input Capacitor Selection
        2. 7.2.3.2 Bootstrap Capacitor Selection
        3. 7.2.3.3 Output Voltage Setpoint
        4. 7.2.3.4 Undervoltage Lockout Setpoint
        5. 7.2.3.5 Inductor Selection
        6. 7.2.3.6 Output Capacitor Selection
        7. 7.2.3.7 Feed-Forward Capacitor
      4. 7.2.4 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.2.3.5 Inductor Selection

Use the following equation to calculate the minimum value of the output inductor (LMIN).

Equation 8. LMIN=VOUT×VIN(MAX)-VOUTVIN(MAX)×KIND×IOUT×fSW

Where:

KIND is a coefficient that represents the amount of inductor ripple current relative to the maximum output current.

In general, the value of KIND is at the discretion of the designer; however, the following guidelines can be used. For designs using low-ESR output capacitors, such as ceramics, a value as high as KIND = 0.3 can be used.

For this design example, use KIND = 0.3. The minimum inductor value is calculated as 11.57μH. For this design, a close standard value of 12μH is selected for LMIN.

For the output filter inductor, the RMS current and saturation current ratings must not be exceeded. Use the following equation to calculate the RMS inductor current (IL(RMS)).

Equation 9. IL(MAX)=IOUT(MAX)2+112×VOUT×VIN(MAX)-VOUTVIN(MAX)×LO×fSW×0.82

Use the following equation to calculate the peak inductor current (IL(PK)).

Equation 10. IL(PK)=IOUT(MAX)+VOUT×VIN(MAX)-VOUTVIN(MAX)×LO×fSW×1.6

Smaller or larger inductor values can be used depending on the amount of ripple current the designer wants to allow so long as the other design requirements are met. Larger value inductors have lower AC current and result in lower output voltage ripple. Smaller inductor values increase AC current and output voltage ripple.