SNVSCZ9 October   2026 LMR70410

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  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 Fixed Frequency Peak Current Mode Control
      2. 7.3.2 Enable and Undervoltage Lockout
      3. 7.3.3 Soft Start and Recovery From Dropout
      4. 7.3.4 Adjustable Output Voltage
      5. 7.3.5 Minimum ON-Time, Minimum OFF-Time and Frequency Foldback
      6. 7.3.6 Bootstrap Voltage
      7. 7.3.7 Overcurrent and Short-Circuit Protection
      8. 7.3.8 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 CCM Mode
      4. 7.4.4 Light-Load Operation (PFM Version)
      5. 7.4.5 Light-Load Operation (FPWM Version)
  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 Output Voltage Setpoint
        2. 8.2.2.2 Switching Frequency
        3. 8.2.2.3 Inductor Selection
        4. 8.2.2.4 Output Capacitor Selection
        5. 8.2.2.5 Input Capacitor Selection
        6. 8.2.2.6 Bootstrap Capacitor
        7. 8.2.2.7 Undervoltage Lockout Setpoint
        8. 8.2.2.8 Replacing Asynchronous Converter
      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 Layout for EMI Reduction
        2. 8.4.1.2 Feedback Resistors
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Mechanical Data

8.2.2.7 Undervoltage Lockout Setpoint

The system undervoltage lockout (UVLO) is adjusted using the external voltage divider network of RENT and RENB. The UVLO has two thresholds, one for power up when the input voltage is rising and one for power down or brown outs when the input voltage is falling. Use Equation 14 to determine the VIN UVLO level.

Equation 14. V I N _ R I S I N G = V E N ( R ) × R E N T + R E N B R E N B

The EN rising threshold (VEN(R)) for LMR70410 is set to be 1.2V (typical). Select a value of 200kΩ for RENB to minimize input current from the supply. If the desired VIN UVLO level is at 6.0V, then use Equation 15 to calculate the value of RENT:

Equation 15. R E N T = ( V I N _ R I S I N G V E N ( R ) - 1 ) × R E N B

The above equation yields a value of 800kΩ, a standard value of 796kΩ is selected. Use Equation 16 to calculate the resulting falling UVLO threshold, equal to 5V.

Equation 16. V I N _ F A L L I N G = V E N ( F ) × R E N T + R E N B R E N B