IEC 61185:2005

IEC 61185 ®
Edition 2.0 2005-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Ferrite cores (ETD-cores) Intended for use in power supply applications –
Dimensions
Noyaux ferrites (noyaux ETD) destinés à être utilisés dans les alimentations –
Dimensions
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IEC 61185 ®
Edition 2.0 2005-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Ferrite cores (ETD-cores) Intended for use in power supply applications –

Dimensions
Noyaux ferrites (noyaux ETD) destinés à être utilisés dans les alimentations –

Dimensions
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX N
ICS 29.100.10 ISBN 978-2-83220-708-6

– 2 – 61185  IEC:2005
CONTENTS
FOREWORD . 3

1 Scope . 5
2 Normative references . 5
3 Primary standards . 5
3.1 Dimensions of ETD-cores . 5
3.2 Dimensional limits for coil formers . 5
3.3 Pin locations and base outlines . 6
3.4 Pin diameter . 6
4 Marking . 6
5 Mounting . 6

Annex A (normative) Derived standards . 11
Annex B (normative) Example of a standard for gauges to check the dimensions of
ETD-cores meeting this primary standard . 14

Figure 1 – Dimensions of ETD-cores . 6
Figure 2 – Essential dimensions of coil formers . 8
Figure 3 – Pin locations and base outlines viewed from the upper-side of the board
(see 3.3) . 10
Figure A.1 – Main dimensions . 12
Figure B.1 – Gauge dimensions . 14

Table 1 – Dimensions of ETD-cores . 7
Table 2 – Effective parameter and A values . 7
min
Table 3 – Essential dimensions of coil formers. 8
Table A.1 – Main dimensions . 13
Table B.1 – Gauge dimensions . 14

61185  IEC:2005 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FERRITE CORES (ETD-CORES) INTENDED
FOR USE IN POWER SUPPLY APPLICATIONS –
DIMENSIONS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61185 has been prepared by IEC technical committee 51:
Magnetic components and ferrite materials.
This second edition cancels and replaces the first edition published in 1992 and its
amendment 1 (1995).
The main changes with respect to the previous edition consist in combining it with the
amendment.
This bilingual version (2013-05) corresponds to the monolingual English version, published in
2005-06.
– 4 – 61185  IEC:2005
The text of this standard is based on the following documents:
FDIS Report on voting
51/818FDIS 51/826/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61185  IEC:2005 – 5 –
FERRITE CORES (ETD-CORES) INTENDED
FOR USE IN POWER SUPPLY APPLICATIONS –
DIMENSIONS
1 Scope
This International Standard specifies the dimensions that are of importance for mechanical
interchangeability for ETD-cores made of ferrite, the essential dimensions of coil formers to
be used with them, and the effective parameter values to be used in calculations involving
them.
NOTE 1 Whilst this standard mainly applies to ferrite, its validity for iron powder cores should not be overlooked.
NOTE 2 The cores covered by this standard are designed for use in power transformers and chokes operating at
high flux density and generally at frequencies higher than those feasible with EC-cores of the same material, due
to a core proportioning more suitable for high-frequency applications. They are generally used in pairs.
The use of “derived” standards which give more detailed specifications of component parts
whilst still permitting compliance with this standard is discussed in Annex A, which also
contains an example of a derived standard for coil formers.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the normative document (including any amendments) applies.
IEC 60205:2001, Calculation of the effective parameters of magnetic piece parts
3 Primary standards
Compliance with the following requirements ensures mechanical interchangeability of
complete assemblies and coil formers.
3.1 Dimensions of ETD-cores
3.1.1 Principal dimensions
The principal dimensions of ETD-cores shall be as given in Table 1.
NOTE The dimensions of the cores may be checked by means of gauges. By way of example, a possible standard
for these gauges is given in Annex B. In order to facilitate production it may be necessary to use gauges having
dimensions differing from those given in Annex B, although no relaxation of the requirements for the dimensions of
the cores given in Table 1 is permitted.
3.1.2 Effective parameter and A values
min
The effective parameter values of a pair of cores whose dimensions comply with 3.1.1 shall
be as given in Table 2.
3.2 Dimensional limits for coil formers
The essential dimensions of coil formers suitable for use with a pair of ETD-cores shall be as
given in Table 3.
– 6 – 61185  IEC:2005
3.3 Pin locations and base outlines
These shall be as shown in Figure 3, in which the base is viewed in the mounting direction, i.e.
from the upper side of the printed wiring board.
NOTE The module, designated as m, shown in the grid plan may be 2,50 mm or 2,54 mm.
3.4 Pin diameter
Coil former terminations (pins) shall be accepted by a gauge having 1,2 mm holes on true
position.
4 Marking
Where a coil former is fitted with termination pins conforming to a 2,50 mm module, it shall be
clearly and indelibly marked with the letter m, in such a position that it can readily be seen in
the completed component.
5 Mounting
According to their sizes and respective weights, it is recommended that two largest cores
(ETD 54 and ETD 59) be fixed on the printed board by means of screws located at two
opposite sides of their coil formers.
Concerning smaller sizes such as ETD 19 and ETD 24, no mounting assemblies are defined.
It is recommended that the two cores be fixed by glue or adhesive tape.

C
B
D
IEC  756/05
Figure 1 – Dimensions of ETD-cores
F
E
A
61185  IEC:2005 – 7 –
Table 1 – Dimensions of ETD-cores
A B C D E F
Size mm mm mm mm mm mm
Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max.
ETD 19 19,1 20,1 13,5 13,8  7,2  7,6  9,2  9,6 14,4 15,4  7,2  7,6
ETD 24 23,8 25,0 14,3 14,6  8,2  8,8  9,9 10,3 18,0 19,2  8,2  8,8
ETD 29 29,0 30,6 15,6 16,0  9,2  9,8 10,7 11,3 22,0 23,4  9,2  9,8
ETD 34 33,4 35,0 17,1 17,5 10,5 11,1 11,8 12,4 25,6 27,0 10,5 11,1
ETD 39 38,2 40,0 19,6 20,0 12,2 12,8 14,2 15,0 29,3 30,9 12,2 12,8
ETD 44 43,0 45,0 22,1 22,5 14,4 15,2 16,1 16,9 32,5 34,1 14,4 15,2
ETD 49 47,6 49,8 24,5 24,9 15,9 16,7 17,7 18,5 36,1 37,9 15,9 16,7
ETD 54 55,8 58,3 27,4 27,8 18,5 19,3 19,8 20,6 40,1 42,3 18,5 19,3
ETD 59 58,4 61,2 30,8 31,2 21,2 22,1 22,0 22,9 43,6 45,8 21,2 22,1

Table 2 – Effective parameter and A values
min
a)
A
C C l A V
min
1 2 e e e
Size
–1 –3 2 3 2
mm mm mm mm mm mm
–3
ETD 19 1,253 9  55,3  44,1  2 440  39,5
28,412 × 10
–3
ETD 24 1,053 7 17,811 × 10  62,3  59,2  3 690  55,0
–3
ETD 29 0,927 07  70,8  76,4  5 410  70,9
12,139 × 10
–3
ETD 34 0,814 49  79,1  97,1  7 680  91,6
8,387 9 × 10
–3
ETD 39 0,742 00  5,940 1 × 10  92,7 125 11 600 123
–3
ETD 44 0,599 18  3,462 8 × 10 104 173 17 900 172
–3
ETD 49 0,542 45 115 211 24 200 209
2,569 2 × 10
–3
EDT 54 0,455 01 127 280 35 700 280
1,625 1 × 10
–3
ETD 59 0,382 24  1,038 9 × 10 141 368 51 700 366
a)
See IEC 60205 sub-clause 2.2 for the definition of A .
min
NOTE 1 The manufacturers may indicate in their catalogues more precise values than those given in Table 2.
NOTE 2 The above values have been calculated using the method given in 3.5 of IEC 60205.

– 8 – 61185  IEC:2005
h
h
IEC  757/05
Figure 2 – Essential dimensions of coil formers

Table 3 – Essential dimensions of coil formers
d d d h h
1 2 3 1 2
Size mm mm mm mm mm
Max. Max. Min. Max. Min.
ETD 19 14,1 9,8 7,8 18,2 15,9
ETD 24 17,6 11,0 9,0 19,6 17,1
ETD 29 21,6 12,0 10,0 21,2 19,2
ETD 34 25,2 13,6 11,3 23,4 20,9
ETD 39 28,8 15,3 13,0 28,2 25,7
ETD 44 32,0 17,7 15,4 32,0 29,5
ETD 49 35,5 19,5 17,0 35,2 32,7
ETD 54 39,5 22,1 19,6 39,3 36,8
ETD 59 43,0 24,9 22,4 43,7 41,2

d
d
d
61185  IEC:2005 – 9 –
4 × (2m)
5 × (2m)
ETD 19
ETD 24
6 × (2m)
m
Earth
6 × (2m)
points
ETD 29 ETD 34
8 × (2m)
m
7 × (2m)
m
Earth Earth
points points
ETD 39 ETD 44
IEC  758/05
Figure 3 – Pin locations and base outlines
viewed from the upper-side of the board (see 3.3)
6 × (2m)
7 × m
5 × (2m)
1,6
1,6
2m
1,6
5 × (2m)
9 × m
7 × (2m)
1,6
1,6
2m
1,6
2m
– 10 – 61185  IEC:2005
9 × (2m)
m
Earth
points
ETD 49
11 × (2m)
ETD 54
12 × (2m)
ETD 59
IEC  759/05
Figure 3 – Pin locations and base outlines viewed
from the upper-side of the board (see 3.3) (continued)
9 × (2m)
10 × (2m)
8 × (2m)
1,6
2m
1,6
3,2
1,6
3,2
61185  IEC:2005 – 11 –
Annex A
(normative)
Derived standards
Clauses 1 to 4 of this primary standard establish the values for the principal dimensions of
core assemblies and wound coil formers and enable full interchangeability for components
complying with this primary standard to be achieved.
Parties interested in making or using ETD-cores may find it desirable to lay down local
standards for everyday use, which show the dimensions and tolerances in greater detail than
Clause 3 and which correspond to the state of the art in that area. These specifications are
known as “derived standards”. When doing so, care should be taken not to exclude any other
type of ETD-core meeting this primary standard that would also satisfy the performance
specification valid for a specific case.
It should be noted that even if a component complies with a derived standard and with the
requirements of Clause 3 of this primary standard, therefore permitting core assemblies and
coil formers to be freely interchanged, its constituent parts may not necessarily be
interchangeable.
When requirements lead to the establishment of a national standard, the relevant national
standardization body is strongly requested to insert a note in such a national standard stating
that:
a) it is in accordance with the dimensional requirement of this present primary standard but
that more details are given in order to promote its practical use;
b) other solutions are possible within the framework of this primary standard and should not
be excluded if the resulting core and formers are functionally interchangeable with those
of the national standard.
By way of example, a possible derived standard for coil formers is given below.
An example of a standard for the main dimensions of coil formers for ETD-cores meeting this
primary standard is given below.

– 12 – 61185  IEC:2005
a h
d h
1 1
d h
2 2
d
p × (2m) q × (2m)
IEC  760/05
(ETD 29, ETD 34, ETD 39, ETD 44 and ETD 49)

h
h
a
d
h
1 1
d h
2 2
d
p × (2m) q × (2m)
IEC  761/05
(ETD 54 and ETD 59)
Figure A.1 – Main dimensions
H
H
61185  IEC:2005 – 13 –
T
...