SLVSI78B January   2025  – December 2025 TPS542021 , TPS542025

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 Modulation
      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 TPS542021 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 Output Filter Components
          1. 7.2.3.5.1 Inductor Selection
          2. 7.2.3.5.2 Output Capacitor Selection
          3. 7.2.3.5.3 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

Package Options

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

6.3.1 Fixed-Frequency PWM Control

The device uses a fixed-frequency, peak current-mode control. For TPS542025, the output voltage is fixed 5V by connecting the FB pin to Vout. For TPS542021, the output voltage is compared through external resistors on the FB pin to an internal voltage reference by an error amplifier. A voltage feedback loop is used to get accurate DC voltage regulation by adjusting the peak current command based on voltage offset. The peak inductor current is sensed from the HS switch and compared to the peak current threshold to control the on time of the HS switch. The voltage feedback loop is internally compensated, which allows for fewer external components, makes design easy, and provides stable operation with almost any combination of output capacitors.

The TPS54202x supplies a regulated output voltage by turning on the HS and LS NMOS switches with controlled duty cycle. During high-side switch on time, the SW pin voltage swings up to approximately VIN, and the inductor current, iL, increases with linear slope (VIN – VOUT) / L. When the HS switch is turned off by the control logic, the LS switch is turned on after an anti-shoot–through dead time. Inductor current discharges through the low-side switch with a slope of –VOUT / L. The control parameter of a buck converter is defined as Duty Cycle D = tON / tSW, where tON is the high-side switch on time and tSW is the switching period. The converter control loop maintains a constant output voltage by adjusting the duty cycle D. In an ideal buck converter where losses are ignored, D is proportional to the output voltage and inversely proportional to the input voltage: D = VOUT / VIN.