Ferrites and accessories
EFD 20/10/7
Core and accessories
Series/Type:
Date:
B66417, B66418
June 2013
Data Sheet
EPCOS AG 2015. Reproduction, publication and dissemination of this publication, enclosures hereto and the information
contained therein without EPCOS' prior express consent is prohibited.
EPCOS AG is a TDK Group Company.
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)
l/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%
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
Gapped
Material
N87
A
L
value
nH
10010%
160
10%
e
120
193
g
approx. mm
0.49
0.25
Ordering code
B66417U0100K187
B66417U0160K187
The A
L
value in the table applies to a core set comprising one ungapped core (dimension g = 0) and
one gapped core (dimension g > 0).
Calculation factors
(for formulas, see
“E cores: general information”
)
Material
Relationship between
air gap – A
L
value
K1 (25 °C)
N87
Validity range:
61.1
K2 (25 °C)
– 0.699
Calculation of saturation current
K3 (25 °C)
85.4
K4 (25 °C)
– 0.796
K3 (100 °C) K4 (100 °C)
75.7
– 0.873
K1, K2: 0.10 mm < s < 1.40 mm
K3, K4: 50 nH < A
L
< 410 nH
Please read
Cautions and warnings
and
Important notes
at the end of this document.
2
06/13
EFD 20/10/7
Accessories
Coil former
GFR thermosetting plastic (UL 94 V-0, insulation class to IEC 60085:
H max. operating temperature 180 °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 Data Book 2013, chapter “Processing notes, 2.1”
Squared pins.
Yoke
Material:
Coil former
Sections
1
A
N
mm
2
28.1
l
N
mm
40.2
A
R
value
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.
3
06/13
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 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 chapter
“Definitions”,
section 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 chapter
“Definitions”,
section 8.2.
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.
Processing notes
– The start of the winding process should be soft. Else the flanges may be destroid.
– To strong winding forces may blast the flanges or squeeze the tube that the cores can no more
be mount.
– To 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 oxyd of the tin bath or burned insulation
of the wire. For detailed information see chapter
“Processing notes”,
section 8.2.
– 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.
4
06/13
Ferrites and accessories
Symbols and terms
Symbols and terms
Symbol
A
A
e
A
L
A
L1
A
min
A
N
A
R
B
B
ˆ
B
ˆ
B
B
DC
B
R
B
S
C
0
CDF
DF
d
E
a
f
f
cutoff
f
max
f
min
f
r
f
Cu
g
H
ˆ
H
H
DC
H
c
h
h/
i
2
I
I
DC
ˆ
I
J
k
k
3
k
3c
L
Meaning
Cross section of coil
Effective magnetic cross section
Inductance factor; A
L
= L/N
2
Minimum inductance at defined high saturation (
a
)
Minimum core cross section
Winding cross section
Resistance factor; A
R
= R
Cu
/N
2
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
5
06/13
Unit
mm
2
mm
2
nH
nH
mm
2
mm
2
= 10
–6
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
Vs/m
2
, mT
F = As/ V
mm
–4.5
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/m
2
J/K
H = Vs/A
嵌入式系统
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