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

3 Description

The LMR60420 is a 3V to 36V (42V transient), 2A synchronous buck converter designed for industrial applications. The LMR60420 offers variants with spread spectrum in an ultra-compact, 2.5mm × 2mm, HotRod QFN-9 package, which reduces inductance and achieves low electromagnetic interference (EMI) performance to facilitate qualification of industrial and other noise-sensitive designs. All device variants are capable of output voltages ranging from 1V to 20V by including a resistor divider between the output voltage node, feedback, and ground. Each variant of the device is also capable of delivering a fixed output voltage by connecting the output voltage node directly to the feedback pin. The Device Comparison Table provides details on the fixed output voltage options. The current-mode control architecture with 40ns minimum on-time allows high conversion ratios at high frequencies, easy loop compensation, fast transient response, and excellent load and line regulation. An open drain power-good output facilitates power sequencing requirements. The MODE/SYNC pin of the LMR60420 allows the user to select between modes of operation. Forced pulse width modulation (FPWM) mode results in constant switching frequency across load while auto mode allows for seamless transitions between pulse width modulation (PWM) and pulse frequency modulation (PFM) switching. In auto mode, the LMR60420 consumes only 5µA of quiescent current, which makes sure of high efficiency at all loads. Few external components are needed allowing for compact PCB layout. The LMR60420 is a part of a family of pin compatible devices ranging in current levels from 0.6A to 6A.

Package Information
PART NUMBERPACKAGE(1)PACKAGE SIZE(2)
LMR60420RAK (WQFN-HR, 9)2.5mm × 2.0mm
(1) For more information, see Section 11.
(2) The package size (length × width) is a nominal value and includes pins, where applicable.