SNVAA93 December   2023 LM65645-Q1 , LM70660 , LM706A0 , LM706A0-Q1 , LM70840 , LM70840-Q1 , LM70860 , LM70860-Q1 , LM70880 , LM70880-Q1 , LMR38020-Q1 , LMR38025-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Conducted Emission Model of Buck Converters
    1. 2.1 DM Noise Emission Model
    2. 2.2 CM Noise Emission Model
  6. 3Reducing Conducted EMI of Buck Converter in 48V DC Power rail
    1. 3.1 Bead Consideration
    2. 3.2 Layout Consideration
    3. 3.3 Power Inductor Consideration
    4. 3.4 Spread Spectrum
  7. 4Summary
  8. 5References

Summary

This application note provides guidance on reducing conducted EMI noise in a buck converter operating in a 48 V automotive system. The key methods discussed include EMI filter considerations, layout optimization, inductor selection, and the use of spread spectrum techniques. These approaches are effective in mitigating EMI noise, particularly in the challenging FM band frequency range commonly found in automotive applications. By following these recommendations, designers can achieve improved EMI performance in their buck converter designs.