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

7.1 Overview

The LMR60420 is a highly efficient 3V to 36V, ultra-low IQ, synchronous buck converter that enables high power density and low EMI. The LMR60420 is designed to minimize the end product cost and size by reducing the number of external passive components required to generate a stable design. Intended for demanding industrial applications, LMR60420 devices have electrical characteristics specified up to a maximum junction temperature of 150ºC.

The LMR60420 offers key features that allow for design flexibility depending on the desired operating conditions:

  • Precision enable through the EN pin allows for accurate power on and power off of the device
  • Switching frequency selection with the RT pin allows designers to select the switching frequency between 200kHz and 2.2MHz
  • The MODE/SYNC pin allows for designers to select the mode of operation, or to synchronize to an external clock frequency
  • The PG pin enables power supply sequencing and notification of the status of the output voltage without the need for external voltage supervisors

Each converter features a pair of integrated power MOSFETs designed for delivering up to 2A of output current. All variants of the LMR60420 allow for every device to be configured to either a fixed output voltage or an adjustable output voltage depending on the presence of feedback resistors. The fixed output voltage setting is determined by the specific orderable part number, which can be found in the Device Comparison Table.

The LMR60420 offers several protection features that make the device an excellent choice for demanding applications. The feedback pin has a voltage rating which makes sure the pin is able to withstand an output voltage short circuit to battery even when in fixed output voltage configuration. The device disables FPWM switching when the input voltage exceeds VINOVP(R) which prevents negative currents from overcharging the input voltage in the event that the output voltage is shorted to the input supply. Thermal shutdown disables switching and allows the LMR60420 to cool before attempting to restart.

The current-mode control architecture with 30ns minimum on-time allows high conversion ratios at high frequencies, easy loop compensation, fast transient response, and excellent load and line regulation. The converters also feature a HotRod package with enhanced spread spectrum that enables low-EMI performance and eases qualification of industrial and noise-sensitive designs.