SLVSFQ0B October   2020  – June 2024 TPS54J061

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  Enable and Internal LDO
      2. 6.3.2  Split Rail and External LDO
      3. 6.3.3  Output Voltage Setting
      4. 6.3.4  Soft Start and Output-Voltage Tracking
      5. 6.3.5  Frequency and Operation Mode Selection
      6. 6.3.6  D-CAP3™ Control Mode
      7. 6.3.7  Current Sense and Positive Overcurrent Protection
      8. 6.3.8  Low-side FET Negative Current Limit
      9. 6.3.9  Power Good
      10. 6.3.10 Overvoltage and Undervoltage Protection
      11. 6.3.11 Out-Of-Bounds Operation (OOB)
      12. 6.3.12 Output Voltage Discharge
      13. 6.3.13 UVLO Protection
      14. 6.3.14 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Auto-Skip Eco-Mode Light Load Operation
      2. 6.4.2 Forced Continuous-Conduction Mode
      3. 6.4.3 Pre-Bias Start-up
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1  Choose the Switching Frequency and Operation Mode (MODE Pin)
        2. 7.2.2.2  Choose the Output Inductor (L)
        3. 7.2.2.3  Set the Current Limit (TRIP)
        4. 7.2.2.4  Choose the Output Capacitors (COUT)
        5. 7.2.2.5  Choose the Input Capacitors (CIN)
        6. 7.2.2.6  Feedback Network (FB Pin)
        7. 7.2.2.7  Soft Start Capacitor (SS/REFIN Pin)
        8. 7.2.2.8  EN Pin Resistor Divider
        9. 7.2.2.9  VCC Bypass Capacitor
        10. 7.2.2.10 BOOT Capacitor
        11. 7.2.2.11 Series BOOT Resistor and RC Snubber
        12. 7.2.2.12 PGOOD Pullup Resistor
      3. 7.2.3 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 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Support Resources
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Trademarks
    5. 8.5 Glossary
    6. 8.6 Electrostatic Discharge Caution
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Ordering Information

7.2.2.2 Choose the Output Inductor (L)

Calculate the inductance value to set the ripple current at approximately 0.3 times the output current using Equation 8. Larger ripple current improves transient response and improves signal-to-noise ratio with the tradeoff of increased steady state output voltage ripple. Smaller ripple current reduces steady state output voltage ripple with the tradeoff of slower transient response and can increase jitter. The target ripple current must be between 0.6 A and 3 A. Based on the result of Equation 8, a standard inductance value of 1 µH was selected.

Equation 8. TPS54J061

Equation 9 calculates the ripple current with the selected inductance. Equation 10 calculates the peak current in the inductor and the saturation current rating of the inductor must be greater than this. The saturation behavior of the inductor at the peak inductor current at current limit must also be considered when choosing the inductor. Equation 11 calculates the RMS current in the inductor and the heat current rating of the inductor must be greater than this.

Equation 9. TPS54J061
Equation 10. TPS54J061
Equation 11. TPS54J061

The selected inductance is a CMLE063T-1R0. This has a saturation current rating of 14 A, RMS current rating of 16 A and a DCR of 6.5 mΩ max. This inductor was selected for the low DCR to get high efficiency.