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

7.3.2 Enable and Undervoltage Lockout

LMR70410 features a precision enable and undervoltage lockout (UVLO) feature which enables the user to select the voltage level at which the device powers on and off based on the voltage present at the EN pin. To power on the device, the voltage between EN pin and GND pin must exceed the enable voltage rising threshold (VEN(R)). After VEN(R) is crossed and the minimum supply voltage (VIN_UVLO(R)) have both been satisfied, the part begins the soft-start sequence described in Section 7.3.3.

The EN pin can be used to power down the device by reducing the voltage between EN pin and GND pin below the enable input falling threshold (VEN(F)).

A resistor divider between VIN and GND with the center point connected to the EN pin can be used to implement the UVLO. To begin, select the input voltage at which the device must turn off, select the value of RENT, then calculate the required RENB. After RENB has been calculated, the resulting turn-on input voltage can be calculated. See Figure 7-2, Equation 1, and Equation 2 to determine the EN resistors required. If the VIN UVLO feature is not needed, the EN pin can be connected to VIN. The EN voltage must not exceed the input voltage.

Equation 1. R E N B = V E N - T H ( F ) V I N t u r n - o f f - V E N - T H ( F ) × R E N T
Equation 2. V I N t u r n - o n = 1 + R E N T R E N B × V E N - T H ( R )

Where:

  • VINturn-off represents the input voltage at which the LMR70410 turns off.
  • VINturn-on represents the input voltage at which the LMR70410 turns on.

LMR70410 VIN UVLO Using the EN Pin Figure 7-2 VIN UVLO Using the EN Pin