EPCOS AG 2017. 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.
Ferrites and accessories
EFD 30/15/9
Core and accessories
Series/Type: B66423, B66424
Date: May 2017
25/17
Please read Cautions and warnings and
Important notes at the end of this document.
E core with flattened, lower center leg
for especially flat transformer design
For DC/DC converters
Delivery mode: single units
Magnetic characteristics (per set)
Σl/A= 0.99 mm
–1
le= 68 mm
Ae= 69 mm2
Amin = 69 mm2
Ve= 4690 mm3
Approx. weight 24 g/set
Ungapped
Other AL values/air gaps and materials available on request – see Processing remarks on page 4.
Gapped (AL values/air gaps examples)
The AL 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).
Calculation factors (for formulas, see “E cores: general information”)
Validity range: K1, K2: 0.10 mm < s < 2.00 mm
K3, K4: 70 nH < AL < 630 nH
Material AL value
nH
μePV
W/set
Ordering code
N87 2050 +30/–20% 1610 < 2.6 (200 mT, 100 kHz, 100 °C) B66423G0000X187
N97 2150 +30/–20% 1690 < 2.2 (200 mT, 100 kHz, 100 °C) B66423G0000X197
Material AL value
nH
μeg
approx. mm
Ordering code
N87 160 ±10% 125 0.71 B66423U0160K187
250 ±10% 196 0.38 B66423U0250K187
315 ±10% 246 0.27 B66423U0315K187
Material Relationship between
air gap – AL value
Calculation of saturation current
K1 (25 °C) K2 (25 °C) K3 (25 °C) K4 (25 °C) K3 (100 °C) K4 (100 °C)
N87 125 0.712 176 0.796 161 0.873
B66423Core
EFD 30/15/9
35/17
Please read Cautions and warnings and
Important notes at the end of this document.
Coil former
Material: 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: Stainless spring steel (0.45 mm)
Coil former Yoke
Coil former Ordering code
Sections AN
mm2
lN
mm
AR value
μΩ
Pins
1 52.3 56.7 37.3 12 B66424W1012D001
Yoke (ordering code per piece, 2 are required) B66424B2000X000
View A
B66424Accessories
EFD 30/15/9
45/17
Please read Cautions and warnings and
Important notes at the end of this document.
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 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
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.
Cautions and warnings
Ferrites and accessories
Cautions and warnings
55/17
Please read Cautions and warnings and
Important notes at the end of this document.
Ferrites and accessories
Display of ordering codes for EPCOS products
The ordering code for one and the same product can be represented differently in data sheets,
data books, other publications and the website of EPCOS, 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.epcos.com/orderingcodes.
Cautions and warnings
65/17
Please read Cautions and warnings and
Important notes at the end of this document.
Symbol Meaning Unit
A
Ae
AL
AL1
Amin
AN
AR
B
ΔB
B
ˆ
ΔB
ˆ
BDC
BR
BS
C0
CDF
DF
d
Ea
f
fcutoff
fmax
fmin
fr
fCu
g
H
H
ˆ
HDC
Hc
h
h/μi2
I
IDC
I
ˆ
J
k
k3
k3c
L
Cross section of coil
Effective magnetic cross section
Inductance factor; AL = L/N2
Minimum inductance at defined high saturation ( μa)
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/μi
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
μΩ = 10–6 Ω
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
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
Symbols and terms
Ferrites and accessories
Symbols and terms
75/17
Please read Cautions and warnings and
Important notes at the end of this document.
Symbol Meaning Unit
ΔL/L
L0
LH
Lp
Lrev
Ls
le
lN
N
PCu
Ptrans
PV
PF
Q
R
RCu
Rh
ΔRh
Ri
Rp
Rs
Rth
RV
s
T
ΔT
TC
t
tv
tan δ
tan δL
tan δr
tan δe
tan δh
tan δ/μi
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 = ωL/Rs = 1/tan δL)
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| /N2 × ε (le/Ae)
H
H
H
H
H
H
mm
mm
W
W
mW/g
Ω
Ω
Ω
Ω
Ω
Ω
Ω
K/W
Ω
mm
°C
K
°C
s
V
V
mm3
Ω
Ω/mm
Symbols and terms
Ferrites and accessories
85/17
Please read Cautions and warnings and
Important notes at the end of this document.
All dimensions are given in mm.
Surface-mount device
Symbol Meaning Unit
α
αF
αe
εr
Φ
η
ηB
ηi
λs
μ
μ0
μa
μapp
μe
μi
μp'
μp"
μr
μrev
μs'
μs"
μtot
ρ
Σl/A
τCu
ω
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 μ(for parallel components)
Relative imaginary (loss) component of μ(for parallel components)
Relative permeability
Relative reversible permeability
Relative real (inductive) component of μ(for series components)
Relative imaginary (loss) component of μ(for series components)
Relative total permeability
derived from the static magnetization curve
Resistivity
Magnetic form factor
DC time constant τCu = L/RCu = AL/AR
Angular frequency; ω = 2 Πf
1/K
1/K
1/K
Vs
mT-1
A–1H–1/2
Vs/Am
Ωm–1
mm–1
s
s–1
Symbols and terms
Ferrites and accessories
95/17
Please read Cautions and warnings and
Important notes at the end of this document.
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.
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, CeraCharge, CeraDiode, CeraLink, CeraPad, CeraPlas, CSMP, CTVS,
DeltaCap, DigiSiMic, ExoCore, FilterCap, FormFit, LeaXield, MiniBlue, MiniCell, MKD, MKK, MotorCap,
PCC, PhaseCap, PhaseCube, PhaseMod, PhiCap, PowerHap, PQSine, PQvar, SIFERRIT, SIFI, SIKOREL,
SilverCap, SIMDAD, SiMic, SIMID, SineFormer, SIOV, ThermoFuse, WindCap 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 2018-10