SNVSCJ2A December   2023  – June 2025 LMR66410-Q1 , LMR66420-Q1 , LMR66430-Q1

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 System Characteristics
    7. 6.7 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, Start-Up, and Shutdown
      2. 7.3.2  External CLK SYNC (With MODE/SYNC)
        1. 7.3.2.1 Pulse-Dependent MODE/SYNC Pin Control
      3. 7.3.3  Adjustable Switching Frequency (With RT)
      4. 7.3.4  Power-Good Output Operation
      5. 7.3.5  Internal LDO, VCC, and VOUT/FB Input
      6. 7.3.6  Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
      7. 7.3.7  Output Voltage Selection
      8. 7.3.8  Spread Spectrum
      9. 7.3.9  Soft Start and Recovery from Dropout
        1. 7.3.9.1 Recovery from Dropout
      10. 7.3.10 Current Limit and Short Circuit
      11. 7.3.11 Thermal Shutdown
      12. 7.3.12 Input Supply Current
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
        1. 7.4.3.1 CCM Mode
        2. 7.4.3.2 Auto Mode – Light Load Operation
          1. 7.4.3.2.1 Diode Emulation
          2. 7.4.3.2.2 Frequency Reduction
        3. 7.4.3.3 FPWM Mode – Light Load Operation
        4. 7.4.3.4 Minimum On-Time (High Input Voltage) Operation
        5. 7.4.3.5 Dropout
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design 1 - Automotive Synchronous Buck Regulator at 2.2 MHz
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Choosing the Switching Frequency
          2. 8.2.1.2.2  Setting the Output Voltage
            1. 8.2.1.2.2.1 VOUT / FB for Adjustable Output
          3. 8.2.1.2.3  Inductor Selection
          4. 8.2.1.2.4  Output Capacitor Selection
          5. 8.2.1.2.5  Input Capacitor Selection
          6. 8.2.1.2.6  CBOOT
          7. 8.2.1.2.7  VCC
          8. 8.2.1.2.8  CFF Selection
          9. 8.2.1.2.9  External UVLO
          10. 8.2.1.2.10 Maximum Ambient Temperature
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Design 2 - Automotive Synchronous Buck Regulator at 400 kHz
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 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 Device Nomenclature
    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

3 Description

The LMR664x0-Q1 is a small 36V, 3A (available in 2A and 1A variants) synchronous step-down DC/DC converter in an enhanced HotRod QFN package. This easy-to-use converter supports a wide input voltage range of 2.7V to 36V (after start-up or after operating) with transients up to 42V.

The LMR664x0-Q1 is specifically designed to meet low standby power requirements for always-on, automotive applications. Auto mode enables frequency foldback when operating at light loads, allowing an unloaded typical current consumption of 1.5µA at 13.5VIN and high light load efficiency. A seamless transition between PWM and PFM modes along with very low MOSFET ON resistances makes sure there is exceptional efficiency across the entire load range. The control architecture (peak current mode) and feature set are optimized for an ultra-small design size with minimal output capacitance. The device minimizes input filter size by using dual-random spread spectrum (DRSS), a low-EMI enhanced HotRod QFN package, and an optimized pinout. The MODE/SYNC pin can be used to set or synchronize the frequency to avoid noise sensitive frequency bands. There are NC pins between critical high voltage pins, reducing potential failures (excellent choice pin FMEA). The rich feature set of the
LMR664x0-Q1 is designed to simplify implementation for a wide range of automotive end equipment.

Package Information
PART NUMBER PACKAGE (1) PACKAGE SIZE(2)
LMR66430-Q1 RXB (VQFN, 14) 2.60mm × 2.60mm
LMR66420-Q1
LMR66410-Q1
(1) For more information, see Section 11.
(2) The package size (length × width) is a nominal value and includes pins, where applicable.
Device Information
PART NUMBER RATED OUTPUT CURRENT (1)
LMR66430-Q1 3A
LMR66420-Q1 2A
LMR66410-Q1 1A