SLVSIY7 August   2025 LM5168E

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Control Architecture
      2. 7.3.2  Internal VCC Regulator and Bootstrap Capacitor
      3. 7.3.3  Internal Soft Start
      4. 7.3.4  On-Time Generator
      5. 7.3.5  Current Limit
      6. 7.3.6  N-Channel Buck Switch and Driver
      7. 7.3.7  Synchronous Rectifier
      8. 7.3.8  Enable/Undervoltage Lockout (EN/UVLO)
      9. 7.3.9  Power Good (PGOOD)
      10. 7.3.10 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 Sleep Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Buck Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Switching Frequency (RT)
        2. 8.2.2.2 Buck Inductor Selection
        3. 8.2.2.3 Setting the Output Voltage
        4. 8.2.2.4 Type 3 Ripple Network
        5. 8.2.2.5 Output Capacitor Selection
        6. 8.2.2.6 Input Capacitor Considerations
        7. 8.2.2.7 CBST Selection
        8. 8.2.2.8 Example Design Summary
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Compact PCB Layout for EMI Reduction
        2. 8.4.1.2 Feedback Resistors
      2. 8.4.2 Thermal Considerations
      3. 8.4.3 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.2.3 Setting the Output Voltage

The LM5168E regulates the output voltage by maintaining the FB voltage equal to the internal reference voltage, VREF = 1.2V (typical). A resistor divider programs the output voltage based on Equation 19.

Equation 19. RFBT=RFBB×VOUTVREF-1

TI recommends selecting RFBB in the range of 10kΩ to 1MΩ for most applications. A larger RFBB consumes less DC current, which is mandatory if light-load efficiency is critical. TI does not recommend RFBB larger than 1MΩ as the feedback path becomes more susceptible to noise. For this example select RFBB = 143kΩ. This action gives RFBT = 453kΩ. Route the feedback trace away from the noisy area of the PCB and keep the feedback resistors close to the FB pin.