3

© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard

E5002_ESD-R-B • 9/14/2018

Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com

EMI Core – ESD-R-B Toroidal Cores for Round Cables for Low & High Frequency (with snail-shaped case)

Magnetic Permeability of Ferrite Material

Inordertoachievemostefficientnoisereduction,itisimportanttoselectthematerialaccordingtothetargetfrequency

band.Dependingonitsmagneticpermeability,aparticularferritematerialwillbeeffectiveinacertainfrequencyband.

Aschematicrepresentationoftherelationshipbetweenthemagneticpermeabilityofeachmaterialandthecorresponding

effectivebandrangeisshowninFigure1.Materialswithhighermagneticpermeabilityareeffectiveinthelowerfrequency

range,whilethosewithlowermagneticpermeabilityareeffectiveinthehigherfrequencyrange.Thus,Mn-Znproductsare

mainlyusedforreducingconductionnoise,whileNi-Znproductsarecommonlyusedforradiationnoisecountermeasures.

Theeffectivefrequencyrangevariesdependingoncoreshape,sizeandnumberofwindings.Thisfrequencydependence

ofthemagneticpermeabilityasshowninthefigureservesforreferencepurposesonlyanditshouldbetestedontheactual

devicetodetermineitseffectiveness.

S18H,S15H,10H,7H,5H,1400Land700LareKEMET’sproprietaryferritematerialnames.

Othermaterialscanalsobeavailableonrequest.

Figure 4 - Relationship between the magnetic permeability of each material and its effective frequency range

10 kHz

0

10,000

20,000

100 kHz

1 MHz

10 MHz

100 MHz

1 GHz

Effective Frequency Range

Ni-Zn Series

1400L

700L

S18H

S15H

10H

7H

5H

Mn-Zn Series

Lower magnetic permeability:

Higher noise suppression effect

in the higher frequency range

Higher magnetic permeability:

Higher noise suppression effect

in the lower frequency range