TIDT260 March   2022

 

  1.   Description
  2.   Features
  3.   Applications
  4. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Considerations
    3. 1.3 Dimensions
  5. 2Testing and Results
    1. 2.1 Efficiency Graphs
    2. 2.2 Load Regulation
    3. 2.3 Line Regulation
    4. 2.4 Thermal Images
      1. 2.4.1 8-V Input Voltage
      2. 2.4.2 18-V Input Voltage
    5. 2.5 Bode Plots
  6. 3Waveforms
    1. 3.1 Switching
    2. 3.2 Output Voltage Ripple
    3. 3.3 Input Voltage Ripple
    4. 3.4 Load Transients
    5. 3.5 Start-Up Sequence
    6. 3.6 Shutdown Sequence
    7. 3.7 Spread Spectrum Feature

Description

This reference design is a small SEPIC converter using the LM5158 device with integrated FET. The main design concern is using the smallest possible board space – setting the switching frequency to 2-MHz which means accepting some switching losses, accepting some magnetizing losses, but maintaining efficiency up to 400 mA at ≥ 80%.

Though the design has been tested up to 800-mA peak load, be aware that the continuous output is limited to 400 mA by thermal interface. Due to a pulsed load, the loop has been squeezed to the maximum bandwidth to enable the lowest output capacitance.

A small RF filter to prevent FM band noise is included, with a total solution size of 30 mm × 20 mm by using a two layer board, single side assembly, and a solid ground plane.