Datasheet
2© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard E5003_ESD-R-H • 9/14/2018
Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com
EMI Core – ESD-R-H Toroidal Cores for Round Cables for Low & High Frequency & High Heat Resistance (with case)
Part Number System
ESD- R- 12 M-H
Series Shape Type
Core Size
Outer Dimension Code (mm)
Core Material
ESD- Ring See Table 1 H / M-H = Mn-Zn
N-H = Ni-Zn
Turns and Impedance Characteristics
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.
A turn is counted by the number of lead-wire windings which pass
through the inner hole of the core. Windings on the outside of the
core do not count.
SeeFigure1forexamplesofone,two,andthreeturns.
Adding turns will result in higher impedance while also lowering
the effective frequency range.
SeeFigure2foranexample.
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
MnZn core material has a lower resistance
compared to the Ni-Zn; therefore, adequate
insulation is required before use.
The Ni-Zn core material is typically effective
for frequencies in the MHz band range such as
the FM-band, while the Mn-Zn core material is
typically effective for the kHz band range such as
the AM-band. See Figure 3.
It is recommended to measure the actual
frequency range effectiveness in the target
application.
3T2T1T
Figure 1 – How to count turns
Impedance Increase
Resonance point changes to lower band
3T
2T
1T
Impedance (Ω)
Frequency (MHz)
10,000
1 10 100 1,000
1,000
100
10
1
Figure 2 – Relationship between impedance and turn count.
(Representative example: ESD-R-16C)
Impedance (Ω)
Frequency (MHz)
AM band range FM band range
Mn-Zn series core
Ni-Zn series core
1,000
100
10
1
0.01 0.1 1 10 100 1,000
Figure 3 – Effective band range of Mn-Zn and Ni-Zn ferrite core material.
(Representative example, measured with same-dimension ring core)