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EE136 Presentation By Dan Lee Dec/6 th /2003

EE136 Presentation By Dan Lee Dec/6 th /2003. Soft Start Electromagnetic Interference. What is Soft Start? Why we need Soft Start?. We want Converter to activate when proper voltage and current are set.

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EE136 Presentation By Dan Lee Dec/6 th /2003

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  1. EE136 Presentation By Dan LeeDec/6th/2003 • Soft Start • Electromagnetic Interference

  2. What is Soft Start?Why we need Soft Start? • We want Converter to activate when proper voltage and current are set. • We want Converter to start with narrow pulse width to prevent excess current from stressing components.

  3. Soft Start 1

  4. Start

  5. Start and Soft Start

  6. Start & Soft Start

  7. What is E.M.I.? • Any unwanted conducted or radiated signals that affect the circuitry. • It requires three conditions to have E.M.I. On the circuitry. 1>Source 2>receiver 3>path

  8. Conducted Mode E.M.I. • Differential or Serial Mode Interference. E.M.I. Between two Lines • Common Mode Interference The E.M.I. Between a Line & Ground

  9. Example of In-Line Filter

  10. How to prevent C.M. E.M.I. from the Switch section!

  11. C.M. E.M.I. • Preventing C.M. E.M.I. Is better than suppressing it with filters. • Once C.M. E.M.I. Is flows through ground, it can propagate to multitude paths.

  12. How to Calculate Components! • Using Foster or Caur method isn’t recommended. Because of difficulty of finding Vo/Vin Transfer Function. • CutOff Freq for C.M. is 18.5Khz. • C.M. C2= Current / (2*Pi* Freq*Voltage) • C.M. L1=1 / (C2*[4*Pi*Freq]^2) • CutOff Freq for D.M. is 16Khz. • D.M. L3=1/ (C4*[4*Pi*Freq]^2)

  13. 8Khz D.M. E.M.I.

  14. 18Khz CutOff D.M. E.M.I.

  15. 18Khz D.M. E.M.I. W/O L. Filters

  16. 1.8Mhz CutOff D.M. E.M.I.

  17. C.M. E.M.I. 5Mhz, 30Volt

  18. C.M. E.M.I. 30V,5Mhz W/O L1 & L2I=30V*w*C=18.8mA

  19. Thank You! • Any Question?

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