EMI Cores
B-20 Series Bead Cores
Overview
KEMET B-20 Series bead cores are
designed for use on round cable. The
wide range of Manganese Zinc (MnZn)
and Nickel Zinc (NiZn) options allows
for targeting of specific frequency
ranges. EMI cores are part of a family
of passive components which address
the issues of noise or electromagnetic
interference (EMI) in circuits or
systems.
EMI Cores
Ring Type
Benefits
EMI Cores
Applications
• MnZn ≤ 100 MHz (AM
Ring Type
band range)
• Consumer electronics
and NiZn ≤ 300 MHz (FM band
EMI Core Usages
Tips on
range) options available
EMI Cores
• Solid construction
Ring Type
Characteristics and how to count turns
Tips on EMI Core Usages
Number
of turns are counted by how many times the lead wire
hole of the core. Do not count the number of lead wire winding
Characteristics and how to count turns
When
desired performance can not be obtained just b
Number
of turns are counted by how many times the lead wire pa
value can be raised b
e turn. In this case,
hole of the core. Do not count the number of lead wire winding
y increasing th
outside the core, as it results
the
When
desired performance can not be obtained just b
value can be raised b
y 1 turn, impedance characteristics
sses through the inner
be checked that it is in the desired range as adding turns resu
e turn. In this case, the
Turns and Impedance Characteristics
Tips on EMI Core Usages
Figure 1 – How to count turns
be checked that it is in the desired range as adding turns resu
10000
y increasing th
e frequency band should
（Rep
10000
lts in lowering down the
sses through the inner
Impedance Increase
2T
1T
2T
3T
100
A turn is counted by the number of lead-wire windings
e frequency band should
value can be raised b
y increasing th
e turn. In this case, the
1T
which pass through the inner hole of the core. Windings
the desired range as adding turns resu
be checked that it is in
lts in lowering down the
1T
2T
Figure 2
3T
Relationship between impedance and turn count.
–
10
*Number of lead wire wound outside the core + 1
on the outside of the core do not count. See Figure 1 for
= Number of read wire passes through the
(Representative example: ESD-R-16C)
inner
hole of the core
ntative Example：ESD-R-16C）
（Represe
examples of one, two, and three turns.
*Number of lead wire wound outside the core + 1
1
10000
= Turn count
When
desired performance can not be obtained just b
y 1 turn, impedance characteristics
Impedance ( )
outside the core, as it results
1000
3T
Resonance point changes to lower
Impedance ( )
100
10
1
1
1000
Fig.1 How to count turns
Impedance ( )
Impedance Increase
Adding turns will result in higher impedance while also
lowering the effective frequency range. See Figure 2 for
an example.
1T
= Number of read wire passes through the inner
hole of the core
= Turn count
1
10
100
Resonance point changes to lower band
1000
Fig.1 How to count turns
3T
2T
Frequency (MHz)
Fig.2 Relationship b
Fig.2 Relationship between impedance an
d turn count
Core Material and Effective Frequency Range
There
are two materials of ferrite, Ni-Zn series and Mn-Zn ser
2T
3T
10
e band range i
1
There
are two materials of ferrite, Ni-Zn series and Mn-Zn ser
1T
100
ies. Ni-Zn series is
e
1000
There are two ferrite material options for
As
Mn-Zn series has lower resistance compared
sure
Ni-Zn seri
Frequency (MHz)
As
Mn-Zn series has lower resistance compared to Ni-Zn series,
make
to
to provide
KEMET EMI Cores: Nickel Zinc (NiZn) and
count turns
Fig.2 Relationship
insulation before
d turn counts
Manganese Zinc (MnZn). Each core material
Fig.1 How to
adequate insulation before use.
adequate
between impedance an
use.
Figure 3 – Effective band range of MnZn and NiZn ferrite core material.
Mn-Zn series vs Ni-Zn series
½ ½
series vs Ni-Zn series
Z -f
has a different resistance and effective
Mn-Zn
Characteristics (representative example)
Z -f
(Representative example,
measured with
with same-dimension ring
½ ½
Characteristics (r
measured
same-dimension ring core)
core)
(measurement condition:
There
are two materials of ferrite, Ni-Zn series and Mn-Zn ser
ies. Ni-Zn series is
e
(measurement condition: measured with same-dimensi
frequency range. The MnZn core material
1000
ive for kHz band range.
1000
has a lower resistance compared to the NiZn;
e band range i
s a reference only. Examination of
s
Note
that above
therefore, adequate insulation is required
actual instrument is necessary.
with
AM band range
FM band range
before use.
As
Mn-Zn series has lower resistance compared to Ni-Zn series,
make sure to provide
AM band range
Note
that above
*Number of lead wire wound outside the core + 1
= Number of read wire passes through the inner
with actual instrument
hole of the core
= Turn count
Note
that above
with actual instrument is necessary.
10
100
is necessary.
1
s a reference only. Examination of
e band range i
ive for kHz band range.
s a reference
s
The NiZn core material is typically effective
100
Mn-Zn series vs Ni-Zn series
½ ½
MnZn series core
Z -f Characteristics (representative example)
for frequencies in the MHz band range such as
(measurement condition: measured with same-dimension ring core)
MnZn series core
the FM-band, while the MnZn core material is
1000
10
typically effective for the kHz band range such
as the AM-band. See Figure 3.
10
FM band range
AM band range
Impedance ( )
Impedance ( )
adequate insulation before use.
100
NiZn series core
NiZn ser
It is recommended to measure the actual
frequency range effectiveness in the target
application.
100
1
MnZn series core
Fig.3
0.01
0.1
Impedance ( )
NiZn series core
1
10
100
1000
1
Frequency (MHz)
0.01
te
One world. One
1
KEMET
0.1
10
Frequency (MHz)
E5009_B-20 • 4/13/2017
1
10
© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com
Fig.3
1
Impedance Increase
When the desired performance of an EMI core cannot
be obtained with a single pass through
Characteristics and how to count turns
the core, the
Number
of turns are counted by how many times the lead wire pa
impedance characteristics can be changed
of
with multiple
count the number of lead wire winding
hole the core. Do not
turns.
（Represe
ntative Example：ESD-R-16C）
1000
EMI
EMI Cores – B-20 Series Bead Cores
KEMET Electronic Corporation Sales Offices
For a complete list of our global sales offices, please visit www.kemet.com/sales.
Disclaimer
All product specifications, statements, information and data (collectively, the “Information”) in this datasheet are subject to change. The customer is responsible for
checking and verifying the extent to which the Information contained in this publication is applicable to an order at the time the order is placed.
All Information given herein is believed to be accurate and reliable, but it is presented without guarantee, warranty, or responsibility of any kind, expressed or implied.
Statements of suitability for certain applications are based on KEMET Electronics Corporation’s (“KEMET”) knowledge of typical operating conditions for such
applications, but are not intended to constitute – and KEMET specifically disclaims – any warranty concerning suitability for a specific customer application or use.
The Information is intended for use only by customers who have the requisite experience and capability to determine the correct products for their application. Any
technical advice inferred from this Information or otherwise provided by KEMET with reference to the use of KEMET’s products is given gratis, and KEMET assumes no
obligation or liability for the advice given or results obtained.
Although KEMET designs and manufactures its products to the most stringent quality and safety standards, given the current state of the art, isolated component
failures may still occur. Accordingly, customer applications which require a high degree of reliability or safety should employ suitable designs or other safeguards
(such as installation of protective circuitry or redundancies) in order to ensure that the failure of an electrical component does not result in a risk of personal injury or
property damage.
Although all product–related warnings, cautions and notes must be observed, the customer should not assume that all safety measures are indicted or that other
measures may not be required.
KEMET is a registered trademark of KEMET Electronics Corporation.
© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com
E5009_B-20 • 4/13/2017
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