Prof R T KennedyEMC & COMPLIANCE ENGINEERING 1 EET 422 EMC & COMPLIANCE ENGINEERING

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 2

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 3 SMPS DISTURBANCES

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 4 I CM I DS I DS = I DM I DS V DS Cp I CM 0 0 0

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 5 INSULATION C M NOISE PATHWAY ~ = I CM

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 6

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 7 DIFFERENTIAL MODE INTERFERENCE

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 8

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 9 COMMON MODE INTERFERENCE

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 10 FLYBACK SMPS CCM DCM

Prof R T KennedyEMC & COMPLIANCE ENGINEERING mV : Excellent 100 mV : Average 1 V : Excessive

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 12 SMPS CONDUCTED EMISSIONS

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 13

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 14

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 15 ‘INTRINSIC’ DIFFERENTIAL MODE NOISE I DS I DS(AC) o o DM noise normally due to SMPS pulsating current ac component LISN presents 100  impedance (2 series 50  if capacitor esl significant then HF DM  source RECTIFIER ‘ON’  HIGHER DM X C  2 k 1 MHz X C  2 M 10 kHz

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 16 ‘INTRINSIC’ DIFFERENTIAL MODE NOISE I DS I DS(AC) o o DM noise normally due to SMPS pulsating current ac component LISN presents 100  impedance (2 series 50  if X C << 100  most DM diverted from LISN X C  2 k 1 MHz X C  2 M 10 kHz

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 17

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 18 COMMON MODE NOISE: MOSFET TURNING ON X C  2 k 1 MHz X C  2 M 10 kHz I DS I DS(AC) V DS o o o CM noise normally due to SMPS parasitic capacitance and LISN presents 25  impedance (2 parallel 50 

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 19

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 20 COMMON MODE NOISE: MOSFET TURNING OFF X C  2 k 1 MHz X C  2 M 10 kHz I DS I DS(AC) V DS o o o CM noise normally due to SMPS parasitic capacitance and LISN presents 25  impedance (2 parallel 50  L N G LISN C esr esL PP

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 21

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 22 COMMON MODE NOISE: PARASITIC CAPACITANCE CM noise normally due to SMPS parasitic capacitance and LISN presents 25  impedance (2 parallel 50  X C  2 k 1 MHz X C  2 M 10 kHz I DS I DS(AC) V DS o o o

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 23 SMPS: INPUT FILTER

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 24 SMPS: NO INPUT FILTER

Prof R T KennedyEMC & COMPLIANCE ENGINEERING 25