SLVSJB8A July   2025  – September 2025 TPS543021

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  Light Load Operation
      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  Adjustable 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 PFM Mode Operation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 TPS543021 6V to 28V Input, 5V Output Converter
      2. 7.2.2 Design Requirements
      3. 7.2.3 Detailed Design Procedure
        1. 7.2.3.1 Custom Design With WEBENCH® Tools
        2. 7.2.3.2 Output Voltage Setpoint
        3. 7.2.3.3 Input Capacitor Selection
        4. 7.2.3.4 Bootstrap Capacitor Selection
        5. 7.2.3.5 Undervoltage Lockout Setpoint
        6. 7.2.3.6 Output Filter Components
          1. 7.2.3.6.1 Inductor Selection
          2. 7.2.3.6.2 Output Capacitor Selection
          3. 7.2.3.6.3 Feedforward 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. 8.1.2 Development Support
        1. 8.1.2.1 Custom Design With WEBENCH® Tools
    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

Package Options

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

7.2.3.3 Input Capacitor Selection

The device requires an input decoupling capacitor, and a bulk capacitor is needed depending on the application. TI recommends a ceramic capacitor over 10µF for the decoupling capacitor. An additional 0.1µF capacitor (C2) from VIN to GND is required for high frequency filtering. The capacitor voltage rating must be greater than the maximum input voltage.

Use the following equation to calculate the input ripple voltage (ΔVIN).

Equation 6. ∆VIN=IOUT(MAX)×0.25CBULK×fSW+IOUT(MAX)×ESRMAX

where:

  • CBULK is the bulk capacitor value
  • fSW is the switching frequency
  • IOUT(MAX) is the maximum loading current
  • ESRMAX is maximum series resistance of the bulk capacitor

The maximum RMS (root mean square) ripple current must also be checked. For worst case conditions, use Equation 7 to calculate ICIN(RMS).

Equation 7. ICIN(RMS)=IOUT(MAX)2

The actual input-voltage ripple is greatly affected by parasitic associated with the layout and the output impedance of the voltage source. Design Requirements shows the actual input voltage ripple for this circuit, which is larger than the calculated value. The maximum voltage across the input capacitors is VIN (MAX) + ΔVIN/2. The selected bypass capacitor is rated for 50V and the ripple current capacity is greater than 2A. Both values provide ample margin. The maximum ratings for voltage and current must not be exceeded under any circumstance.