SLUS593J December   2003  – June 2022 TPS40054 , TPS40055 , TPS40057

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Recommended Operating Conditions
    3. 6.3 Thermal Information
    4. 6.4 Electrical Characteristics
    5. 6.5 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Setting the Switching Frequency (Programming the Clock Oscillator)
      2. 7.3.2 Programming The Ramp Generator Circuit
      3. 7.3.3 UVLO Operation
      4. 7.3.4 BP5 and BP10 Internal Voltage Regulators
      5. 7.3.5 Programming Soft Start
      6. 7.3.6 Programming Current Limit
      7. 7.3.7 Synchronizing to an External Supply
      8. 7.3.8 Loop Compensation
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Selecting the Inductor Value
      2. 8.1.2 Calculating the Output Capacitance
      3. 8.1.3 Calculating the Boost and BP10 Bypass Capacitor
      4. 8.1.4 DV-DT Induced Turn-On
      5. 8.1.5 High-Side MOSFET Power Dissipation
      6. 8.1.6 Synchronous Rectifier MOSFET Power Dissipation
      7. 8.1.7 TPS4005x Power Dissipation
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Calculate Maximum and Minimum Duty Cycles
        2. 8.2.2.2  Select Switching Frequency
        3. 8.2.2.3  Select ΔI
        4. 8.2.2.4  Calculate the High-Side MOSFET Power Losses
        5. 8.2.2.5  Calculate Synchronous Rectifier Losses
        6. 8.2.2.6  Calculate the Inductor Value
        7. 8.2.2.7  Set the Switching Frequency
        8. 8.2.2.8  Program the Ramp Generator Circuit
        9. 8.2.2.9  Calculate the Output Capacitance (CO)
        10. 8.2.2.10 Calculate the Soft-Start Capacitor (CSS/SD)
        11. 8.2.2.11 Calculate the Current Limit Resistor (RILIM)
        12. 8.2.2.12 Calculate Loop Compensation Values
        13. 8.2.2.13 Calculate the Boost and BP10V Bypass Capacitance
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 MOSFET Packaging
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2 Typical Application

Figure 8-2 shows component selection for the 10-V to 24-V to 3.3-V at 8 A DC-to-DC converter specified in the design example. For an 8-V input application, it can be necessary to add a Schottky diode from BP10 to BOOST to get sufficient gate drive for the upper MOSFET. As seen in Figure 6-4, the BP10 output is about 6 V with the input at 8 V, so the upper MOSFET gate drive can be less than 5 V.

A Schottky diode is shown connected across the synchronous rectifier MOSFET as an optional device that can be required if the layout causes excessive negative SW node voltage, greater than or equal to 2 V.

GUID-D2270E30-BC0B-4DA6-86B3-97E16CE4DC0E-low.gifFigure 8-2 24-V to 3.3-V at 8-A DC-DC Converter Design Example