EFD 20/10/7
Core
■
E core with flattened, lower center leg
B66417
for especially flat transformer design
■
For DC/DC converters
■
Delivery mode: single units
Magnetic characteristics
(per set)
Σl/A
l
e
A
e
A
min
V
e
= 1.52 mm
–1
= 47 mm
= 31 mm
2
= 31 mm
2
= 1460 mm
3
Approx. weight
7.2 g/set
Ungapped
Material
N49
N87
N97
A
L
value
nH
910 +30/–20%
1200 +30/–20%
1250 +30/–20%
μ
e
1100
1440
1510
P
V
W/set
< 0.29 ( 50 mT, 500 kHz, 100 °C)
< 1.05 (200 mT, 100 kHz, 100 °C)
< 0.80 (200 mT, 100 kHz, 100 °C)
Ordering code
B66417G0000X149
B66417G0000X187
B66417G0000X197
Other A
L
values/air gaps and materials available on request – see Processing remarks on page 5.
Gapped
(A
L
values/air gaps examples)
Material
A
L
value
nH
N87
100
±10%
160
±10%
250
±10%
330 ±10%
400 ±12%
450 ±15%
120
193
300
398
483
543
μ
e
g
approx.
mm
0.49
0.25
0.13
0.09
0.07
0.06
Ordering code
B66417U0100K187
B66417U0160K187
B66417U0250K187
B66417U0330K187
B66417U0400H187
B66417U0450L187
The A
L
value in the table applies to a core set comprising one ungapped core (dimension g = 0 mm)
and one gapped core (dimension g > 0 mm).
Please read
Cautions and warnings
and
Important notes
at the end of this document.
2
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EFD 20/10/7
Accessories
Coil former
GFR thermosetting plastic (UL 94 V-0, insulation class to IEC 60085:
F max. operating temperature 155 °C), color code black
Sumikon PM 9630
®
[
E41429 (M)
]
, SUMITOMO BAKELITE CO LTD
Solderability: to IEC 60068-2-20, test Ta, method 1 (aging 3): 235 °C, 2 s
Resistance to soldering heat: to IEC 60068-2-20, test Tb, method 1B: 350 °C, 3.5 s
Winding:
see Processing notes, 2.1
Pins:
Squared pins
Yoke
Material:
Coil former
Sections
1
A
N
mm
2
28.1
l
N
mm
40.2
A
R
value
μΩ
49.2
Pins
8
B66418W1008D001
B66418B2000X000
Stainless spring steel (0.3 mm)
Ordering code
Material:
B66418
Yoke (ordering code per piece, 2 are required)
Coil former
Yoke
View A
Please read
Cautions and warnings
and
Important notes
at the end of this document.
4
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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 tempera-
ture 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 A
L
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
EPCOS ferrite accessories have been designed and evaluated only in combination with EPCOS
ferrite cores. EPCOS explicitly points out that EPCOS ferrite accessories or EPCOS ferrite cores
may not be compatible with those of other manufacturers. Any such combination requires prior te-
sting by the customer and will be at the customer‘s own risk.
EPCOS assumes no warranty or reliability for the combination of EPCOS 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 arrange-
ment.
– 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 insula-
tion 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.
5
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