SNVAA87 august   2023 LMR38020

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Micro Inverter System
    2. 1.2 Typical Power Tree and Design Requirements
  5. 2Conventional Flyback Design Challenges
    1. 2.1 SSR Design Challenges
    2. 2.2 PSR Design Challenges
  6. 3New Fly-Buck Design
    1. 3.1 LMR38020 Overview
    2. 3.2 Comparison with Conventional Flyback
    3. 3.3 Design Considerations
    4. 3.4 LMR38020 Fly-Buck Design Example
  7. 4Bench Test and Result
    1. 4.1 Start Up
    2. 4.2 Typical Switching Waveforms Under Steady State
    3. 4.3 Efficiency
    4. 4.4 Load Regulation
    5. 4.5 Short Circuit
    6. 4.6 Thermal Performance
  8. 5Summary
  9. 6References

3.1 LMR38020 Overview

The LMR38020 is a 4.2 V to 80 V, 2-A synchronous buck converter in HSOIC-8 package. The power MOSFETs as well as the loop compensation network are all integrated to reduce external component count making the LMR38020 designed for implementation of a Fly-Buck™ converter as the auxiliary bias supply in micro inverter applications.

The LMR38020's absolute maximum rating of VIN to PGND is 85 V, which is designed for micro inverter with PV panel having maximum 60 V output voltage (around 30% margin, which is adequate for long term reliability). The recommended maximum load current capability is 2 A, which is also enough for the auxiliary power of micro inverter which usually does not exceed 10 W power need.