SLVAFD4 February   2024 TPS54308 , TPS54320 , TPS54350 , TPS54620 , TPS54622 , TPS54821 , TPS54824 , TPS62933F

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Components Selection for Secondary Stage Filter
  6. 3Experimental Validation
  7. 4How to Estimate Inductance of Ferrite Bead for Ripple Reduction
  8. 5Summary
  9. 6References
  10. 7Appendix

5 Summary

A components selection method for second stage filter is proposed in this application note to satisfy low output ripple requirement. With frequency domain analysis, the high frequency gain attenuation effects of second stage filter are studied first. Applying the gain attenuation effects on first stage output voltage ripple, the relation between second stage filter components value and second stage output voltage ripple is derived, which can directly guide the components selection.

To be noted, the effects of second stage filter on converter loop stability is not considered in this application note. In the Peak Current Mode Converter Secondary Stage Filter Design for Low Ripple Power – Part II: Hybrid Sense Network Design for Stability application note, the stability analysis and components selection method for stability restriction are discussed.