EMI Cores
Ring Type
Tips on EMI Core Usages
■Characteristics and how to count turns
ꢀNumber of turns are counted by how many times the lead wire passes through the inner
hole of the core. Do not count the number of lead wire winding outside the core, as it results
in different turn count. (Fig. 1)
ꢀWhen desired performance can not be obtained just by 1 turn, impedance characteristics
value can be raised by increasing the turn. In this case, the effective frequency band should
be checked that it is in the desired range as adding turns results in lowering down the
effective band range. (Fig. 2)
(Representative Example:ESD-R-16C)
10000
Resonance point changes to lower band
1000
3T
2T
100
1T
1T
2T
3T
10
1
*Number of lead wire wound outside the core + 1
= Number of read wire passes through the inner
hole of the core
1
10
100
1000
= Turn count
Frequency (MHz)
Fig.2ꢀRelationship between impedance and turn counts
Fig.1ꢀHow to count turns
■Effective band range depending on core material
ꢀThere are two materials of ferrite, Ni-Zn series and Mn-Zn series. Ni-Zn series is effective
for MHz band range such as FM band while Mn-Zn series is effective for kHz band range.
ꢀNote that above effective band range is a reference only. Examination of effectiveness
with actual instrument is necessary.
ꢀAs Mn-Zn series has lower resistance compared to Ni-Zn series, make sure to provide
adequate insulation before use.
Mn-Zn series vs Ni-Zn series|Z|-f Characteristics (representative example)
(measurement condition: measured with same-dimension ring core)
1000
AM band range
FM band range
Ni-Zn series core
100
10
1
Mn-Zn series core
0.01
0.1
1
10
100
1000
Frequency (MHz)
Fig.3ꢀEffective Band Range of Mn-Zn series / Ni-Zn series ferrite
EMI Core
5
●All specifications in this catalog and production status of products are subject to change without notice. Prior to the purchase, please contact NEC TOKIN for updated product data.
●Please request for a specification sheet for detailed product data prior to the purchase.
●Before using the product in this catalog, please read "Precautions" and other safety precautions listed in the printed version catalog.
9634ESDVOL09E1003E1