Ferrites and accessories
Toroids (ring cores)
General information and overview
Date:
October 2022
TDK Electronics AG 2022. Reproduction, publication and dissemination of this publication, enclosures hereto
and the information contained therein without TDK Electronics’ prior express consent is prohibited.
Toroids (ring cores)
General information
Toroids (ring cores)
Our product line includes a wide range of toroids with finely graded diameters ranging from 2.5 to
202 mm.
Other core heights can be supplied on request. All cores are available in the usual materials.
1
Applications
Toroids are primarily used as EMC chokes for suppressing RF interference in the MHZ region
and in signal transformers.
Typical applications for toroids of NiZn ferrites are LAN chokes. One of the materials available
for this purpose is K10; other materials on request.
The following high-permeability MnZn materials are available for interference suppression:
– R 2.5 through R 12.5 for telecommunications (N30, T38, T46)
– R 13.3 through R 26 for power line chokes (N30, T65, T35, T37, T38)
– >R 34 for chokes and filters in industrial use (T65)
Toroids are also increasingly used for power applications. Here, the typical values for amplitude
permeability and power loss, as summarized in the section on “SIFERRIT Materials”, are applicable to the special power materials.
2
Coating
Toroids are available in different coating versions, thus offering the appropriate solution for every
application. The coating not only offers protection for the edges but also provides an insulation function.
For small ring cores, we have introduced a parylene coating which features a low coating thickness
and high dielectric strength.
A coating of the core will cause μi to drop, depending on the core size. A similar effect might occur
when the core is subjected to high winding forces, especially cores made of the high permeability
materials, T38 and T46.
Please read Cautions and warnings and
Important notes at the end of this document.
2
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Toroids (ring cores)
General information
Coatings of ring cores
Version
Epoxy
(blue)
Parylene
(transparent)
Main application
Medium/big sizes
(R 9.53)
Small sizes
(1.5 kV (for R 12.5 thru R 20)
>2.0 kV (for >R 20)
>1 kV
(standard value)
Mechanical quality
High firmness
Smooth surface
Maximum temperature
(short-time)
approx. 180 C
approx. 130 C
Maximum temperature
(long-time)
approx. 130 C
approx. 130 C
Advantage
Low influence on AL value
Very low thickness
UL rating
UL 94 V-0
UL 94 V-0
UL file number
E194412/E257941
E194412
Ordering code
B64290L…
B64290P…
3
Dielectric strength test
The following test setup is used to test the dielectric strength of the insulating coating: A copper ring
is pressed to the top edge of the ring. It touches the ferrite ring at the edges (see diagram).
The test duration is 2 seconds.
Ferrite ring
Vrms
Metal poles
Please read Cautions and warnings and
Important notes at the end of this document.
3
10/22
Toroids (ring cores)
General information
4
Chamfer
Large toroidal cores use thick wires that are partially subjected to high mechanical stress during
winding. This can damage the wire insulation as well as the coating of the cores, thus reducing the
breakdown voltage. To avoid this, TDK Electronic toroids have a chamfer. This prevents any insulation damage, and produces uniform coating thickness at the same time.
FUS0127-3
5
Core size
Design
Small
Edges rounded by tumbling
Medium
Chamfer on edges and/or radius on the surface
Medium/big
Chamfer on edges
Cutting
Middle size and large toroids are available with gap:
1.) Cut into 2 halves with typical cuting wheel
thickness 1.2 mm.
2.) Cut gap in required thickness.
Three basic questions have to be answered during order:
– toroid cuts into 2 halves/only gap (picture 1 or 2)
– cutting before/after coating
– before: air gap is coated
– after: air gap is not coated, a measurement fixture can be placed into the air gap
– required thickness of the gap
Toroids have uniform cross-section that leads to uniform flux density and fully utilization of material
saturation limit. Advantage is simple compact and economic shape.
Gapped ferrite toroids are mainly used as power inductors for converters where gap enables high
currents without saturation. Also the price is lower despite the core with larger cross-section is usually needed. These cores can be used in applications like buck, boost, forward, push-pull and resonant converters, power factor correction choke or differential filter inductor.
Please read Cautions and warnings and
Important notes at the end of this document.
4
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Toroids (ring cores)
General information
6
Structure of the ordering code (part number)
Please read Cautions and warnings and
Important notes at the end of this document.
5
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Toroids (ring cores)
Overview
di
B64290
h
da
FUS0138-I
Overview of available sizes
Type
Toroid size (da di h)
mm
Type code
(ordering code, block 2)
inch
R 2.50 1.50 1.00
R 0.098 0.059 0.039
P0035
R 2.50 1.50 1.30
R 0.098 0.059 0.051
P0072
R 2.54 1.27 1.27
R 0.100 0.050 0.050
P0734
R 3.05 1.27 1.27
R 0.120 0.050 0.050
P0683
R 3.05 1.27 2.54
R 0.120 0.050 0.100
P0739
R 3.05 1.78 2.03
R 0.120 0.070 0.080
P0733
R 3.43 1.78 1.78
R 0.135 0.070 0.070
P0731
R 3.43 1.78 2.03
R 0.135 0.070 0.080
P0745
R 3.94 1.78 1.78
R 0.155 0.070 0.070
P0732
R 3.94 2.24 1.30
R 0.155 0.088 0.051
P0061
R 3.94 2.24 2.30
R 0.155 0.088 0.090
P0723
R 4.00 2.40 1.60
R 0.157 0.094 0.063
P0036
R 4.00 2.40 1.80
R 0.157 0.094 0.071
P0692
R 5.84 3.05 1.52
R 0.230 0.120 0.060
P0056
R 5.84 3.05 3.00
R 0.230 0.120 0.118
P0687
R 6.30 3.80 2.50
R 0.248 0.150 0.098
P0037
R 8.00 4.00 4.00
R 0.315 0.158 0.158
P0751
R 9.53 4.75 3.17
R 0.375 0.187 0.125
L0062
R 10.0 6.00 4.00
R 0.394 0.236 0.157
L0038
R 10.0 6.00 7.00
R 0.394 0.236 0.318
L0783
R 12.5 7.50 5.00
R 0.492 0.295 0.197
L0044
R 12.7 7.90 6.35
R 0.500 0.311 0.250
L0742
R 13.3 8.30 5.00
R 0.524 0.327 0.197
L0644
R 14.0 9.00 5.00
R 0.551 0.354 0.197
L0658
R 15.0 10.4 5.30
R 0.591 0.409 0.209
L0623
R 15.8 8.90 4.70
R 0.622 0.350 0.185
L0743
R 16.0 9.60 6.30
R 0.630 0.378 0.248
L0045
Please read Cautions and warnings and
Important notes at the end of this document.
6
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Toroids (ring cores)
Overview
di
B64290
h
da
FUS0138-I
Overview of available sizes (continued)
Type
Toroid size (da di h)
mm
Type code
(ordering code, block 2)
inch
R 17.0 10.7 6.80
R 0.669 0.421 0.268
L0652
R 18.4 5.90 5.90
R 0.724 0.232 0.232
L0697
R 20.0 10.0 7.00
R 0.787 0.394 0.276
L0632
R 20.0 10.0 10.0
R 0.787 0.394 0.394
L0631
R 20.0 10.0 15.0
R 0.787 0.394 0.591
L0710
R 22.1 13.7 6.35
R 0.870 0.539 0.250
L0638
R 22.1 13.7 7.90
R 0.870 0.539 0.311
L0719
R 22.1 13.7 12.5
R 0.870 0.539 0.492
L0651
R 22.6 14.7 9.20
R 0.890 0.579 0.362
L0626
R 25.3 14.8 10.0
R 0.996 0.583 0.394
L0618
R 25.3 14.8 15.0
R 0.996 0.583 0.590
L0615
R 25.3 14.8 20.0
R 0.996 0.583 0.787
L0616
R 29.5 19.0 14.9
R 1.142 0.748 0.587
L0647
R 30.5 20.0 12.5
R 1.201 0.787 0.492
L0657
R 34.0 20.5 10.0
R 1.339 0.807 0.394
L0058
R 34.0 20.5 12.5
R 1.339 0.807 0.492
L0048
R 36.0 23.0 15.0
R 1.417 0.906 0.591
L0674
R 38.1 19.05 12.7
R 1.500 0.750 0.500
L0668
R 40.0 24.0 16.0
R 1.575 0.945 0.630
L0659
R 41.8 26.2 12.5
R 1.646 1.031 0.492
L0022
R 50.0 30.0 20.0
R 1.969 1.181 0.787
L0082
R 58.3 32.0 18.0
R 2.295 1.260 0.709
L0043
R 58.3 40.8 17.6
R 2.295 1.606 0.693
L0040
R 58.3 40.8 20.2
R 2.295 1.606 0.795
L0042
R 63.0 38.0 25.0
R 2.480 1.496 0.984
L0699
R 68.0 48.0 13.0
R 2.677 1.890 0.512
L0696
R 87.0 54.3 13.5
R 3.425 2.138 0.531
L0730
R 102 65.8 15.0
R 4.016 2.591 0.591
L0084
Please read Cautions and warnings and
Important notes at the end of this document.
7
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Toroids (ring cores)
Overview
Type
Toroid size (da di h)
mm
Type code
(ordering code, block 2)
inch
R 140 103 25.0
R 5.512 4.055 0.984
A0705
R 202 153 25.0
R 7.953 6.024 0.984
A0711
Please read Cautions and warnings and
Important notes at the end of this document.
8
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Ferrites and accessories
Cautions and warnings
Cautions and warnings
Mechanical stress and mounting
Ferrite cores have to meet mechanical requirements during assembling and for a growing number
of applications. Since ferrites are ceramic materials one has to be aware of the special behavior
under mechanical load.
As valid for any ceramic material, ferrite cores are brittle and sensitive to any shock, fast temperature changing or tensile load. Especially high cooling rates under ultrasonic cleaning and high static
or cyclic loads can cause cracks or failure of the ferrite cores.
For detailed information see data book, chapter “General - Definitions, 8.1”.
Effects of core combination on AL value
Stresses in the core affect not only the mechanical but also the magnetic properties. It is apparent
that the initial permeability is dependent on the stress state of the core. The higher the stresses are
in the core, the lower is the value for the initial permeability. Thus the embedding medium should
have the greatest possible elasticity.
For detailed information see data book, chapter “General - Definitions, 8.1”.
Heating up
Ferrites can run hot during operation at higher flux densities and higher frequencies.
NiZn-materials
The magnetic properties of NiZn-materials can change irreversible in high magnetic fields.
Ferrite Accessories
Our ferrite accessories have been designed and evaluated only in combination with our ferrite
cores. We explicitly point out that our ferrite accessories or our ferrite cores may not be compatible
with those of other manufacturers. Any such combination requires prior testing by the customer and
will be at the customer‘s own risk.
We assume no warranty or reliability for the combination of our ferrite accessories with cores and
other accessories from any other manufacturer.
Processing remarks
The start of the winding process should be soft. Else the flanges may be destroyed.
– Too strong winding forces may blast the flanges or squeeze the tube that the cores can not be
mounted any more.
– Too long soldering time at high temperature (>300 °C) may effect coplanarity or pin arrangement.
– Not following the processing notes for soldering of the J-leg terminals may cause solderability
problems at the transformer because of pollution with Sn oxyde of the tin bath or burned insulation of the wire. For detailed information see chapter “Processing notes”, section 2.2.
– The dimensions of the hole arrangement have fixed values and should be understood as
a recommendation for drilling the printed circuit board. For dimensioning the pins, the group
of holes can only be seen under certain conditions, as they fit into the given hole arrangement.
To avoid problems when mounting the transformer, the manufacturing tolerances for positioning
the customers’ drilling process must be considered by increasing the hole diameter.
Please read Cautions and warnings and
Important notes at the end of this document.
9
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Ferrites and accessories
Cautions and warnings
Display of ordering codes for TDK Electronics products
The ordering code for one and the same product can be represented differently in data sheets, data
books, other publications, on the company website or in order-related documents such as shipping
notes, order confirmations and product labels. The varying representations of the ordering
codes are due to different processes employed and do not affect the specifications of the
respective products. Detailed information can be found on the Internet under
www.tdk-electronics.tdk.com/orderingcodes.
Please read Cautions and warnings and
Important notes at the end of this document.
10
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Ferrites and accessories
Symbols and terms
Symbols and terms
Symbol
Meaning
Unit
A
Ae
AL
AL1
Amin
AN
AR
B
B
ˆ
B
Bˆ
BDC
BR
BS
C0
CDF
DF
d
Ea
f
fcutoff
fmax
fmin
fr
fCu
g
H
ˆ
H
HDC
Hc
h
h/i 2
I
IDC
ˆI
J
k
k3
k3c
L
Cross section of coil
Effective magnetic cross section
Inductance factor; AL = L/N2
Minimum inductance at defined high saturation ( a)
Minimum core cross section
Winding cross section
Resistance factor; AR = RCu /N2
RMS value of magnetic flux density
Flux density deviation
Peak value of magnetic flux density
Peak value of flux density deviation
DC magnetic flux density
Remanent flux density
Saturation magnetization
Winding capacitance
Core distortion factor
Relative disaccommodation coefficient DF = d/i
Disaccommodation coefficient
Activation energy
Frequency
Cut-off frequency
Upper frequency limit
Lower frequency limit
Resonance frequency
Copper filling factor
Air gap
RMS value of magnetic field strength
Peak value of magnetic field strength
DC field strength
Coercive field strength
Hysteresis coefficient of material
Relative hysteresis coefficient
RMS value of current
Direct current
Peak value of current
Polarization
Boltzmann constant
Third harmonic distortion
Circuit third harmonic distortion
Inductance
mm2
mm2
nH
nH
mm2
mm2
= 10–6
Vs/m2, mT
Vs/m2, mT
Vs/m2, mT
Vs/m2, mT
Vs/m2, mT
Vs/m2, mT
Vs/m2, mT
F = As/ V
mm–4.5
Please read Cautions and warnings and
Important notes at the end of this document.
11
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J
s–1, Hz
s–1, Hz
s–1, Hz
s–1, Hz
s–1, Hz
mm
A/m
A/m
A/m
A/m
10–6 cm/A
10–6 cm/A
A
A
A
Vs/m2
J/K
H = Vs/A
Ferrites and accessories
Symbols and terms
Symbol
Meaning
Unit
L/L
L0
LH
Lp
Lrev
Ls
le
lN
N
PCu
Ptrans
PV
PF
Q
R
RCu
Rh
Rh
Ri
Rp
Rs
Rth
RV
s
T
T
TC
t
tv
tan
tanL
tanr
tane
tanh
tan/i
U
Û
Ve
Z
Zn
Relative inductance change
Inductance of coil without core
Main inductance
Parallel inductance
Reversible inductance
Series inductance
Effective magnetic path length
Average length of turn
Number of turns
Copper (winding) losses
Transferrable power
Relative core losses
Performance factor
Quality factor (Q = L/Rs = 1/tanL)
Resistance
Copper (winding) resistance (f = 0)
Hysteresis loss resistance of a core
Rh change
Internal resistance
Parallel loss resistance of a core
Series loss resistance of a core
Thermal resistance
Effective loss resistance of a core
Total air gap
Temperature
Temperature difference
Curie temperature
Time
Pulse duty factor
Loss factor
Loss factor of coil
(Residual) loss factor at H 0
Relative loss factor
Hysteresis loss factor
Relative loss factor of material at H 0
RMS value of voltage
Peak value of voltage
Effective magnetic volume
Complex impedance
Normalized impedance |Z|n = |Z| /N 2 (le /Ae)
H
H
H
H
H
H
mm
mm
Please read Cautions and warnings and
Important notes at the end of this document.
12
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W
W
mW/g
K/W
mm
°C
K
°C
s
V
V
mm3
/mm
Ferrites and accessories
Symbols and terms
Symbol
Meaning
Unit
F
e
r
B
i
s
0
a
app
e
i
p'
p"
r
rev
s'
s"
tot
Temperature coefficient (TK)
Relative temperature coefficient of material
Temperature coefficient of effective permeability
Relative permittivity
Magnetic flux
Efficiency of a transformer
Hysteresis material constant
Hysteresis core constant
Magnetostriction at saturation magnetization
Relative complex permeability
Magnetic field constant
Relative amplitude permeability
Relative apparent permeability
Relative effective permeability
Relative initial permeability
Relative real (inductive) component of (for parallel components)
Relative imaginary (loss) component of (for parallel components)
Relative permeability
Relative reversible permeability
Relative real (inductive) component of (for series components)
Relative imaginary (loss) component of (for series components)
Relative total permeability
derived from the static magnetization curve
Resistivity
Magnetic form factor
DC time constant Cu = L/RCu = AL/AR
Angular frequency; = 2 f
1/K
1/K
1/K
l/A
Cu
All dimensions are given in mm.
Surface-mount device
Please read Cautions and warnings and
Important notes at the end of this document.
13
10/22
Vs
mT-1
A–1H–1/2
Vs/Am
m–1
mm–1
s
s–1
Important notes
The following applies to all products named in this publication:
1. Some parts of this publication contain statements about the suitability of our products for
certain areas of application. These statements are based on our knowledge of typical requirements that are often placed on our products in the areas of application concerned. We nevertheless expressly point out that such statements cannot be regarded as binding statements
about the suitability of our products for a particular customer application. As a rule, we
are either unfamiliar with individual customer applications or less familiar with them than the customers themselves. For these reasons, it is always ultimately incumbent on the customer to
check and decide whether a product with the properties described in the product specification is
suitable for use in a particular customer application.
2. We also point out that in individual cases, a malfunction of electronic components or failure before the end of their usual service life cannot be completely ruled out in the current
state of the art, even if they are operated as specified. In customer applications requiring a
very high level of operational safety and especially in customer applications in which the malfunction or failure of an electronic component could endanger human life or health (e.g. in accident prevention or life-saving systems), it must therefore be ensured by means of suitable design of the customer application or other action taken by the customer (e.g. installation of protective circuitry or redundancy) that no injury or damage is sustained by third parties in the event
of malfunction or failure of an electronic component.
3. The warnings, cautions and product-specific notes must be observed.
4. In order to satisfy certain technical requirements, some of the products described in this publication may contain substances subject to restrictions in certain jurisdictions (e.g. because they are classed as hazardous). Useful information on this will be found in our Material
Data Sheets on the Internet (www.tdk-electronics.tdk.com/material). Should you have any more
detailed questions, please contact our sales offices.
5. We constantly strive to improve our products. Consequently, the products described in this
publication may change from time to time. The same is true of the corresponding product
specifications. Please check therefore to what extent product descriptions and specifications
contained in this publication are still applicable before or when you place an order.
We also reserve the right to discontinue production and delivery of products. Consequently, we cannot guarantee that all products named in this publication will always be available. The
aforementioned does not apply in the case of individual agreements deviating from the foregoing
for customer-specific products.
6. Unless otherwise agreed in individual contracts, all orders are subject to our General Terms
and Conditions of Supply.
Please read Cautions and warnings and
Important notes at the end of this document.
14
10/22
7. Our manufacturing sites serving the automotive business apply the IATF 16949 standard.
The IATF certifications confirm our compliance with requirements regarding the quality management system in the automotive industry. Referring to customer requirements and customer specific requirements (“CSR”) TDK always has and will continue to have the policy of respecting individual agreements. Even if IATF 16949 may appear to support the acceptance of unilateral requirements, we hereby like to emphasize that only requirements mutually agreed upon can
and will be implemented in our Quality Management System. For clarification purposes we
like to point out that obligations from IATF 16949 shall only become legally binding if individually
agreed upon.
8. The trade names EPCOS, CarXield, CeraCharge, CeraDiode, CeraLink, CeraPad, CeraPlas,
CSMP,
CTVS, DeltaCap, DigiSiMic, ExoCore, FilterCap, FormFit, InsuGate, LeaXield,
MiniBlue, MiniCell, MKD, MKK, ModCap, MotorCap, PCC, PhaseCap, PhaseCube, PhaseMod,
PhiCap, PowerHap, PQSine, PQvar, SIFERRIT, SIFI, SIKOREL, SilverCap, SIMDAD, SiMic,
SIMID, SineFormer, SIOV, ThermoFuse, WindCap, XieldCap are trademarks registered or
pending in Europe and in other countries. Further information will be found on the Internet at
www.tdk-electronics.tdk.com/trademarks.
Release 2022-07
Please read Cautions and warnings and
Important notes at the end of this document.
15
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