SNVSCU7A July   2025  – August 2026 LM65440-Q1 , LM65460-Q1

PRODMIX  

  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 Descriptions
      1. 7.3.1  Output Voltage Selection
      2. 7.3.2  EN Pin and Use as VIN UVLO
      3. 7.3.3  Mode Selection
        1. 7.3.3.1 MODE/SYNC Pin Uses for Synchronization
        2. 7.3.3.2 Clock Locking
      4. 7.3.4  Adjustable Switching Frequency
      5. 7.3.5  Dual Phase Operation
      6. 7.3.6  Dual Randrom Spread Spectrum (DRSS)
      7. 7.3.7  Internal LDO, VCC UVLO, and BIAS Input
      8. 7.3.8  Bootstrap Voltage (BST Pin)
      9. 7.3.9  Soft Start and Recovery From Dropout
      10. 7.3.10 Safety Features
        1. 7.3.10.1 Power-Good Monitor
        2. 7.3.10.2 Overcurrent and Short-Circuit Protection
        3. 7.3.10.3 Hiccup
        4. 7.3.10.4 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
        1. 7.4.2.1 Peak Current Mode Operation
        2. 7.4.2.2 Auto Mode Operation
          1. 7.4.2.2.1 Diode Emulation
        3. 7.4.2.3 FPWM Mode Operation
        4. 7.4.2.4 Dropout
        5. 7.4.2.5 Recovery from Dropout
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Choosing the Switching Frequency
        3. 8.2.2.3 FB for Adjustable or Fixed Output Voltage Mode
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Output Capacitor Selection
        6. 8.2.2.6 Input Capacitor Selection
        7. 8.2.2.7 CBOOT
        8. 8.2.2.8 External UVLO
        9. 8.2.2.9 Maximum Ambient Temperature
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Ground and Thermal Considerations
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    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

7.3.7 Internal LDO, VCC UVLO, and BIAS Input

The LM654x0-Q1 has a dual input for the VCC regulator that is supplied from either VIN or BIAS. After the LM654x0-Q1 is active, power comes from VIN if BIAS is less than approximately 3.1V. However, power comes from BIAS if BIAS is more than 3.2V (maximum). VCC is typically 3.3V under most conditions, but can be lower if VIN is very low. To prevent unsafe operation, VCC has a UVLO that prevents switching if the internal voltage is too low. See VCC-UVLO_R and VCC-UVLO_HYST in Electrical Characteristics. TI recommends a 1μF capacitor rated for 10V with X7R or better dielectric for the VCC capacitor.