EMI Core
ESD-R Series Toroidal Cores
Overview
Benefits
Applications
The KEMET ESD-R Series solid
toroidal cores are designed for use on
round cable. A wide range of MnZn
and NiZn options are available in Bare,
Coated, and Case types.
•ꢀ MnZnꢀ(≤ꢀ100ꢀMHz,ꢀAMꢀbandꢀrange)ꢀ
andꢀNiZnꢀ(≤ꢀ300ꢀMHz,ꢀFMꢀbandꢀ
range) options available
• Solid construction
• Bare, Coated, and Case types
available
• Consumer
electronics
Turns and Impedance Characteristics
Figure 1 – How to count turns
When the desired performance of an EMI core cannot
be obtained with a single pass through the core, the
impedance characteristics can be changed with multiple
turns.
1T
2T
3T
A turn is counted by the number of lead-wire windings
which pass through the inner hole of the core. Windings
onꢀtheꢀoutsideꢀofꢀtheꢀcoreꢀdoꢀnotꢀcount.ꢀSeeꢀFigureꢀ1ꢀforꢀ
examples of one, two, and three turns.
Figure 2 – Relationship between impedance and turn count.
(Representative example: ESD-R-16C)
10000
Resonance point changes to lower band
Adding turns will result in higher impedance while also
loweringꢀtheꢀeffectiveꢀfrequencyꢀrange.ꢀSeeꢀFigureꢀ2ꢀforꢀ
an example.
1000
3T
2T
1T
100
10
1
Core Material and Effective Frequency Range
There are two ferrite material options for
KEMET EMI Cores: Nickel-Zinc (Ni-Zn) and
Manganese-Zinc (Mn-Zn). Each core material
has a different resistance and effective
frequency range. The Mn-Zn core material
has lower resistance compared to the Ni-
Zn; therefore, be sure to provide adequate
insulation before use.
1
10
100
1000
Frequency (MHz)
Figure 3 – Effective band range of Mn-Zn and Ni-Zn ferrite core material.
(Representative example, measured with same-dimension ring core)
1000
AM band range
MnZn series core
FM band range
NiZn series core
Forꢀreference,ꢀtheꢀNi-Znꢀcoreꢀmaterialꢀisꢀ
typically effective for the frequencies in the
MHzꢀbandꢀrangeꢀsuchꢀasꢀtheꢀFM-band,ꢀwhileꢀ
the Mn-Zn core material is typically effective for
theꢀkHzꢀbandꢀrangeꢀsuchꢀasꢀtheꢀAM-band.ꢀSeeꢀ
Figureꢀ3.
100
10
1
It is recommended to verify actual
effectiveness in the target application with
measurements.
0.01
0.1
1
10
100
1000
Frequency (MHz)
One world. One KEMET
© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com
E5001_ESD-R • 3/28/2017
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