ZHCSMT4C October   2021  – November 2022 LMR51420

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 System Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Fixed Frequency Peak Current Mode Control
      2. 8.3.2 Adjustable Output Voltage
      3. 8.3.3 Enable
      4. 8.3.4 Minimum On Time, Minimum Off Time, and Frequency Foldback
      5. 8.3.5 Bootstrap Voltage
      6. 8.3.6 Overcurrent and Short-Circuit Protection
      7. 8.3.7 Soft Start
      8. 8.3.8 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Active Mode
      3. 8.4.3 CCM Mode
      4. 8.4.4 Light-Load Operation (PFM Version)
      5. 8.4.5 Light-Load Operation (FPWM Version)
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Output Voltage Set-Point
        3. 9.2.2.3 Switching Frequency
        4. 9.2.2.4 Inductor Selection
        5. 9.2.2.5 Output Capacitor Selection
        6. 9.2.2.6 Input Capacitor Selection
        7. 9.2.2.7 Bootstrap Capacitor
        8. 9.2.2.8 Undervoltage Lockout Set-Point
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Compact Layout for EMI Reduction
        2. 9.4.1.2 Feedback Resistors
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 第三方产品免责声明
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 接收文档更新通知
    4. 10.4 支持资源
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 术语表
  11. 11Mechanical, Packaging, and Orderable Information

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8.1 Overview

The LMR51420 is an easy-to-use synchronous step-down DC-DC converter operating from a 4.5-V to 36-V supply voltage. The device is capable of delivering up to 2-A DC load current in a very small solution size. The family has multiple versions applicable to various applications. See Section 5 for detailed information.

The LMR51420 employs fixed-frequency peak-current mode control. The PFM version enters PFM mode at light load to achieve high efficiency. A FPWM version is provided to achieve low output voltage ripple, tight output voltage regulation, and constant switching frequency at light load. The device is internally compensated, which reduces design time and requires few external components.

Additional features such as precision enable and internal soft start provide a flexible and easy-to-use solution for a wide range of applications. Protection features include the following:

  • Thermal shutdown
  • VIN undervoltage lockout
  • Cycle-by-cycle current limit
  • Hiccup mode short-circuit protection

This family of devices requires very few external components and has a pinout designed for simple, optimal PCB layout.