SLVAFJ9 March   2023 TPSF12C1 , TPSF12C1-Q1 , TPSF12C3 , TPSF12C3-Q1

 

  1.   Abstract
  2. 1 Table of Contents
  3.   Trademarks
  4. 2 Introduction
  5. 3 EMI Frequency Ranges
  6. 4 Passive EMI Filters for High-Power, Grid-Tied Applications
  7. 5 Active EMI Filters
  8. 6 Generalized AEF Circuits
  9. 7 Selection of the CM Active Filter Circuit
  10. 8 The Concept of Capacitive Amplification
  11. 9 Practical AEF Implementations
  12. 10Practical Results
    1. 10.1 Low-Voltage Testing
    2. 10.2 High-Voltage Testing
  13. 11Summary
  14. 12References

2 Introduction

Common-mode (CM) EMI filters for high-density applications often have a limit to the total value of Y-capacitance – related to touch-current safety requirements – and thus require large-sized CM chokes to achieve a target corner frequency or filter attenuation characteristic. The result is a compromised passive filter design with bulky, heavy and expensive CM chokes that dominate the overall filter size.

However, active EMI filter (AEF) circuits enable more compact filter designs for next-generation power management systems. As such, space-constrained applications can use active power-supply filter integrated circuits (ICs) to reduce magnetic component and overall filter size. Ancillary benefits include lower power losses for better thermal management and higher reliabilty, easier mechanical and packaging designs, reduced electromagnetic coupling among components within a confined space, and lower cost.