SNAS879 December   2024 LMR60420

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 Description
      1. 7.3.1 Enable and Undervoltage Lockout (UVLO)
      2. 7.3.2 Soft Start and Recovery from Dropout
      3. 7.3.3 Frequency Selection With RT
      4. 7.3.4 MODE/SYNC Pin Control
      5. 7.3.5 Output Voltage Selection
      6. 7.3.6 Current Limit
      7. 7.3.7 Hiccup Mode
      8. 7.3.8 Power-Good Function
      9. 7.3.9 Spread Spectrum
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown
      2. 7.4.2 Active Mode
        1. 7.4.2.1 Continuous Conduction Mode (CCM)
        2. 7.4.2.2 Auto Mode - Light Load Operation
        3. 7.4.2.3 FPWM Operation - Light Load Operation
        4. 7.4.2.4 Minimum On-Time
        5. 7.4.2.5 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 Switching Frequency Selection
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 Input Capacitor Selection
        5. 8.2.2.5 Bootstrap Capacitor (CBOOT) Selection
        6. 8.2.2.6 FB Voltage Divider for Adjustable Output Voltages
          1. 8.2.2.6.1 Feedforward Capacitor (CFF) Selection
        7. 8.2.2.7 RPG - PG Pullup Resistor
      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 Ground and Thermal Plane Considerations
      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

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.4.2 Active Mode

The LMR60420 is in an active mode whenever the EN pin voltage has risen above VEN-TH(R), the input voltage exceeds VINUVLO(R), and no other fault conditions are present. The simplest way to enable the LMR60420 is to connect the EN pin to VIN, which allows self start-up when the applied input voltage exceeds the VINUVLO(R).

In active mode, the LMR60420 is in one of the following modes:

  • Continuous conduction mode (CCM) with fixed switching frequency when the load current is above half of the inductor current ripple
  • Auto mode - light load operation: pulse frequency modulation (PFM) where switching frequency is reduced at light load
  • FPWM mode - light load operation: CCM mode when the load current is lower than half of the inductor current ripple
  • Minimum on-time: at high input voltage and low output voltages, the switching frequency is reduced to maintain regulation
  • Dropout mode: when switching frequency is reduced to minimize voltage dropout between input and output