SNVAA43 March   2023 LM5157 , LM5157-Q1 , LM51571-Q1 , LM5158 , LM5158-Q1 , LM51581 , LM51581-Q1


  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Application Parameters
  5. 3Calculations and Component Selection
    1. 3.1 Switching Frequency
    2. 3.2 Coupled Inductor Selection
      1. 3.2.1 Coupling Capacitor (AC Cap)
    3. 3.3 Diode Selection
    4. 3.4 MOSFET Selection
    5. 3.5 Output Capacitor Selection
    6. 3.6 Input Capacitor Selection
    7. 3.7 Output Voltage Setting
  6. 4Simplified SEPIC Schematic
  7. 5References


This report focuses on designing the power stage for a SEPIC converter. The design procedure is generic on selecting suitable components of the SEPIC power stage for the given application specifications. The LM5155EVM-SEPIC evaluation module is used as the example to illustrate the design procedure, and the circuit performance results are also presented in the LM5155EVM-SEPIC User's Guide. For typical applications the LM5155 and LM5156 Quickstart Calculator for SEPIC Regulator Design (Rev. A) can also be used to efficiently complete the calculations described in this report.