EMI. RC RCD RCD Abstract: The application of RCD circuit in converter can realize low cost and low parts cout .How to design that circuit is introduced. Keyword: RCD clamp, Flyback converter (100w) RCDRCDRCD RCD RCD Vclamp: Vin: VD: Lp: Llk: RCDLpLlkLp,LlkRCDLlk RCD LlkRc RCD RCD RcCcCc VclampRCD Vclamp 2RCD VOR VclampCc VBR(DSS) VINMAX VclampVBR(DSS)0.9Vclamp Llk Rc CcVclamp 1%--5% PR-clamp WR-clamp Wl VOR Vclamp (3) fs Llk Ids-peak() (2)(4) Cc Cc5%--10%,Cc Cc Vclamp Vclamp Rc fs 1/3 RCDRC f 300M EMC150KHz-30MHz300M()EMC40MHz 1.200K20M 2.200K 3.20M 4.PCB 100M500mv 1.PCB 2. , ACTRACE, , . ,(),(),. 022X10Y X ,, “”CMG“” 50W,3PININLET(FGDC),2PININLET, LISN 1YY2 2-3 Y DX GJB 151A CE101 sometimes: 35253842 cmg: : ADVANTAGES: Fast transient response Single pole compensation Inherent current limiting DISADVANTAGES: Noise sensitivity to current spikes Dual feedback loops Slope compensation Current limit tail : ADVANTAGES: Single feedback loop Good noise immunity Low impedance output RDS(ON) highly accurate DISADVANTAGES: Double pole compensation Slow dynamic response Output caps affect compensation PWM ESR1m1iLm2iL m1=Vs/T m2=VoR/LMN (1.1) 1 <0.5>0.52 2.a<0.5iiL<i,. 2.b,>0.5iiL>i,< >0.5im1,<0.5 iVs(Ton)VcVcVsVcVsVc Vc3-mVc iL=-i(m+m2)/(m+m1) (1.2) 1m10,iLTL,(1.2)m m > -0.5m2 (1.3) m0.75,Vom2(1.3), 35% 1/n1/21/3 1/21/2 , 3844MOSFET 3RC3844 Y-CAP,EMIEMI