ALT Series Tech Journal Datasheet by TDK Corporation

View All Related Products | Download PDF Datasheet
T ‘CII ()[TRNAL
01
In recent years, LAN connectors have become standard equipment not only on computers and other IT products but also in digital
TV sets as well as many other types of audiovisual appliances and consumer products. Pulse transformers are key components used
in such LAN interfaces. The transformers must convey pulse signals at high speed and at the same time provide other functionality
such as insulation between the input and output. TDK has applied its extensive technological know-how gained in developing SMD
(surface mount device) type common mode filters to create a new kind of SMD pulse transformer manufactured using an automated
coil winding technique. Conventional devices with hand-laid windings suffer from various problems such as uneven characteristics
due to manufacturing tolerances. By contrast, the new pulse transformers from TDK offer excellent uniformity and provide comparable
performance as existing products at a much smaller footprint. The ALT series is bound to become a new reference in this field.
The New Reference LAN Pulse Transformer
SMD Pulse Transformer for Ethernet Applications
ALT Series
Fascinating, Fast, Accurate Communication
SMD Pulse Transformer for Ethernet Applications
The Ethernet standard, which is now is the dominant worldwide
format for LAN (local area networks), was developed in the
early 1980s in the U.S. It was originally designed to link
workstations in research facilities, businesses, and similar
professional environments. But along with the evolution of the
personal computer, LAN became a widely adopted solution for
connecting multiple PCs, and the LAN market grew by leaps
and bounds. A linkup of separate LANs over a greater distance
is called a WAN (wide area network), while a connection
between multiple computers and audiovisual devices in a home
is called a home network or home LAN. Unlike wireless LANs,
an Ethernet LAN requires a cable connection, but this enables
very reliable data transmission at much higher speeds.
There are various Ethernet formats which differ in aspects such
as the type of cable connection and the transfer speed. These
are defined by the respective standards and indicated by terms
such as 100BASE-T or 1000BASE-T. The former is rated for a
transfer speed (throughput rate) of 100 Mbps, while the latter
achieves speeds as high as 1000 Mbps (1 gigabit per second).
The "T" indicates that the format uses twisted pair cable.
02
□Schematic Diagram of
 LAN and WAN
□Evolution of Ethernet (Wired LAN) and Wireless LAN
Ethernet
Ethernet
Home
LAN
LAN WAN (Wide Area Network)
LAN
LAN
LAN
LAN
Internet etc.
Dedicated
Line
《Office》 《Plant / Research Facility》
Transfer rate
10G
1G
100M
10M
1980 1990 2000 2010 from 2020
(bps)
10G BASE-T
becomes widespread
1000 BASE-T
becomes widespread
100 BASE-TX
becomes widespread
10 BASE-T
becomes widespread
IEEE 802.11ac
(max. 6.9G Mbps)
IEEE 802.11n
(max. 600 Mbps)
IEEE 802.11a/g
(max.54 Mbps)
IEEE 802.11b
(max.11 Mbps)
IEEE 802.11ad
(max. 6.8G Mbps)
Ethernet Became Dominant LAN Format Along With Progress of Computers
DDomestic LAN and Interface Components da—
SMD Pulse Transformer for Ethernet Applications
Electronic devices equipped with a LAN connector have an
integrated LAN adapter that allows the device to be linked to a
network simply by plugging in the cable. Before LAN adapters
became standard on the motherboards of PCs, they usually
were available in the form of plug-in cards designed to be
inserted into a slot of the computer. One of the reasons why
adapters now are integrated in computers is the spread of
broadband Internet connections.
A LAN connector, also called a LAN port, looks somewhat
similar to a modular phone jack, with slightly bigger dimensions.
This is called an RJ45 connector. Internally, the RJ45 connector
signals are routed via common mode choke coils (filters) to
the pulse transformer and then to the transceiver IC. A LAN
connector module integrates the RJ45 connector, common
mode choke coils, and pulse transformer into a single compact
unit.
The pulse transformer is a special kind of transformer designed
to transmit pulse waveform signals. Unlike a power transformer,
its purpose is not to transmit power, therefore it can be made
considerably more compact, allowing it to fit into the connector
module.
Domestic LAN and Interface Components
Common Mode Choke Coils
LAN Connector Modules
Pulse Transformers
TV Set
DVD Recorder
Home Gateway
Ethernet
Surveillance Camera
Multi-Function Printer
Access Point
IP Telephone Computer
03
Pulse Transformer: Key Component of a LAN Interface
:Conventional Pulse Transformer with . i a] MA > '4 i): :Pulse Transformer with New Core Structure
SMD Pulse Transformer for Ethernet Applications
A pulse transformer employs a simple construction built
around a toroidal (ring-shaped) core on which the primary and
secondary coils are wound. However, although the operation
principle and construction are simple, pulse transformers
are actually quite difficult electronic components to build
well. Aspects such as design, choice of core material, and
winding method affect the outcome considerably, and uniform
characteristics are not easy to achieve.
Compared to other transformers with cores that inherently
have air gaps, a toroidal transformer has lower leakage flux
and can therefore deliver better performance. Consequently,
pulse transformers traditionally were designed as toroidal
transformers, but due to their shape, the coils normally
are hand-wound because automated winding is difficult to
implement. This unavoidably results in tolerances between
finished units and presents an obstacle to stable quality and
mass production.
Not only personal computers but also many other types of
equipment these days such as digital TVs and audiovisual
appliances routinely come with LAN connectors. Pulse
transformers for LAN applications therefore have become a
highly sought-after product. If the toroidal core shape is taken
as a given, automated winding is not feasible and the needs of
the market are difficult to meet.
The ALT series of SMD pulse transformers from TDK represents
a radical departure. By thinking outside the box, our engineers
have come up with a solution that enables a manufacturing
process that uses automated winding.
The development team took a hint from SMD type common
mode filters that are used extensively as noise suppressing
components. A common mode filter is similar to a pulse
transformer in that it employs two windings on a toroidal core.
To enable mass production, TDK developed a pioneering
approach that uses automated winding on a drum core and
then joins it with a flat plate core. It turned out that a very
similar core construction and automated winding method as for
SMD type common mode filters can in fact be applied to pulse
transformers. This led to the development of the new SMD type
pulse transformers.
New Manufacturing Method Based on a Breakthrough Idea
The magnetic flux created by the windings travels
through the inside of the core, but when there is a gap,
some of the flux will leak to the outside (leakage flux).
This results in degraded coupling between the primary
and secondary windings.
After automated
winding on drum core,
the plate core is
attached.
Magnetic flux travels
through the interior of
both cores, providing the
functional equivalent of a
toroidal core.
Magnetic flux escapes
through gap in core
Windings
Plate Core
Winding
Connecting
Line
Rectangular
Drum Core
Terminal
Electrode
Rectangular
Drum Core
Plate Core Magnetic Flux
Winding
Connecting
Line
Terminal
Electrode
Rectangular
Drum Core
Winding
Plate Core
《Toroidal Core》
Common Mode Filter
Construction
SMD Type Pulse Transformer
《Conventional Pulse Transformer》
Conventional Pulse Transformer with
 Toroidal Core
Core Gap and Leakage Flux
Pulse Transformer with New Core Structure
The magnetic flux created by the windings travels
through the inside of the core, but when there is a gap,
some of the flux will leak to the outside (leakage flux).
This results in degraded coupling between the primary
and secondary windings.
●After automated
winding on drum core,
the plate core is
attached.
●Magnetic flux travels
through the interior of
both cores, providing the
functional equivalent of a
toroidal core.
Magnetic flux escapes
through gap in core
Windings
Plate Core
Winding
Connecting
Line
Rectangular
Drum Core
Terminal
Electrode
Rectangular
Drum Core
Plate Core Magnetic Flux
Winding
Connecting
Line
Terminal
Electrode
Rectangular
Drum Core
Winding
Plate Core
《Toroidal Core》
Common Mode Filter
Construction
SMD Type Pulse Transformer
《Conventional Pulse Transformer》
Conventional Pulse Transformer with
 Toroidal Core
Core Gap and Leakage Flux
Pulse Transformer with New Core Structure
04
Conventional Method: Manual Winding on Toroidal Core
DMagnetization Curve and DC Superposition i... 11%|
SMD Pulse Transformer for Ethernet Applications
The strength of the coupling between the primary and secondary
windings on a transformer is expressed as the coupling coefficient (k).
In an ideal transformer, this would be 1, but in the real world, leakage
flux and other factors result in a coefficient k that is smaller than 1.
A key aspect of transformer design therefore is the question of how
to achieve a coefficient that approaches 1 as closely as possible. As
described above, the air gap in a transformer core causes leakage
flux leading to leakage inductance which degrades the performance
of the transformer. By designing a new core shape that lends itself to
automated winding, TDK was able to reduce the gap at the juncture
between the drum core and plate core to less than half, resulting in a
significant reduction of leakage flux.
The winding design also is important with respect to lowering
the coupling coefficient. Transformer windings are subject to a
phenomenon called parasitic capacitance that does not show up
in circuit diagrams. Although windings are electrically isolated, the
potential difference causes adjacent windings to act like the electrodes
of a capacitor. This type of parasitic capacitance is called intra-
winding capacitance. In addition, there is also another type of parasitic
capacitance, namely the winding distribution capacitance between the
primary and secondary winding. Reducing these parasitic capacitance
involves a tradeoff, because this reduction results in increased
leakage inductance. Achieving good winding design therefore requires
advanced technical know-how that is not easy to come by.
Because pulse waveforms usually cover a very wide frequency
range, the choice of core material is crucial to prevent excessive
pulse waveform distortion that can degrade the signal.
For example, a pulse transformer for a 100BASE-T Ethernet
connection is required to have an inductance value of at
least 350 microhenry (µH) when a DC bias of 8 mA is applied.
The outstanding DC superposition characteristics of ferrite
therefore are highly desirable, since the magnetization curve
remains linear also when a DC bias magnetic field is applied.
(Waveform distortion increases towards the curved portion of
the characteristics plot.) A ferrite material that offers both high
magnetic permeability and high saturation flux density and that
exhibits these characteristics over the entire temperature range
existing in a normal LAN environment is required.
Making use of its extensive experience with ferrite technology,
TDK developed a ferrite material optimized for pulse transformer
applications. Both material composition and microstructure
were carefully reconsidered to achieve this goal. In the ALT
series, a new material that meets the technical requirements of
next-generation high-speed LANs is used.
Adopting Ferrite as the Ideal Core for a Pulse Transformer
The coupling
between the primary
winding and
secondary winding is
called the coupling
coefficient (k). In the
ideal transformer, the
coupling coefficient k
is equal to 1.
In an actual
transformer, leakage
flux and parasitic
capacitance caused
by adjacent windings
acting like a
capacitor results in a
coupling coefficient
that is lower than 1.
Select ferrite material
where linear portion
of magnetization
curve can be used.
With this selection,
curved portion of
magnetization curve
will be used,
resulting in higher
waveform distortion.
《Waveform distortion》
Overshoot,
undershoot,
ringing, etc.
In a pulse transformer for LAN applications, a DC bias magnetic field is
applied. The higher the magnetic permeability and magnetic flux density
of the ferrite core, the better the DC superposition characteristics.
If core material selection and winding structure design are
unsuitable, the square pulse waveform will be significantly
distorted, leading to impaired transfer characteristics and noise.
Signal
Source
Signal
Source
Winding Distribution Capacitance
Input
waveform
Ferrite material with high
magnetic flux density
and high magnetic
permeability
DC bias
magnetic
field
Input
H: Magnetic field strength
B: Magnetic flux density
Output
waveform
Primary
Winding
Core
Intra-Winding Capacitance
Secondary
Winding
Load Load
Magnetization Curve and DC Superposition
 Characteristics of a Ferrite Core
Causes of Pulse Waveform Distortion
Parasitic Capacitance Caused
 by Transformer Windings
The coupling
between the primary
winding and
secondary winding is
called the coupling
coefficient (k). In the
ideal transformer, the
coupling coefficient k
is equal to 1.
In an actual
transformer, leakage
flux and parasitic
capacitance caused
by adjacent windings
acting like a
capacitor results in a
coupling coefficient
that is lower than 1.
Select ferrite material
where linear portion
of magnetization
curve can be used.
With this selection,
curved portion of
magnetization curve
will be used,
resulting in higher
waveform distortion.
《Waveform distortion
Overshoot,
undershoot,
ringing, etc.
In a pulse transformer for LAN applications, a DC bias magnetic field is
applied. The higher the magnetic permeability and magnetic flux density
of the ferrite core, the better the DC superposition characteristics.
If core material selection and winding structure design are
unsuitable, the square pulse waveform will be significantly
distorted, leading to impaired transfer characteristics and noise.
Signal
Source
Signal
Source
Winding Distribution Capacitance
Input
waveform
Ferrite material with high
magnetic flux density
and high magnetic
permeability
DC bias
magnetic
field
Input
H: Magnetic field strength
B: Magnetic flux density
Output
waveform
Primary
Winding
Core
Intra-Winding Capacitance
Secondary
Winding
Load Load
Magnetization Curve and DC Superposition
 Characteristics of a Ferrite Core
Causes of Pulse Waveform Distortion
Parasitic Capacitance Caused
 by Transformer Windings
05
Winding Design Requires Advanced Technical Know-How
DEye Pattern Evaluation Sample in Ethernet Application :Comparison of Footprint (looBASE-TX Example) an an an an an an an an an an an
SMD Pulse Transformer for Ethernet Applications
The ALT series delivers the high reliability and performance
required of a pulse transformer for LAN applications, and it
does so in a compact SMD type package manufactured with
automated winding, something that was considered very
difficult to realize. As can be seen from the eye pattern shown
at right, signal integrity is on the same level as with conventional
products, although the SMD package is notably smaller.
The ALT series of pulse transformers not only utilizes
automated winding for the coils, it also employs automated
thermo compression bonding for the terminal electrodes and
wires. With conventional products, manual wire processing and
soldering are required. Automating these steps results in more
uniform quality.
The manufacturing process for conventional products is
semi-automated, with batch processing being employed for
the stages from electrical testing to taping. By contrast, the
manufacturing process for the ALT series is continuous and fully
automated.
The pulse transformer is normally integrated in the LAN module
along with the common mode choke coils and other parts. With
conventional components, complex wiring as well as soldering
tasks had to be performed manually when mounting the pulse
transformer. The parts were then fixed with resin. Because the
ALT series transformers are SMD components, they can be
mounted along with other parts during the reflow stage, greatly
simplifying the process and reducing the number of required
work hours.
Another advantage is the more compact dimensions that
contribute to space savings. When combined with noise
removal according to the differential transfer method, the
required footprint can be reduced by about 40 to 60% (using
single-unit board mounting in combination with the ACM series
common mode filters from TDK).
The ALT series like its predecessor products is designated
by TDK as a fully lead-free "environment-conscious" product
that completely eliminates lead and lead compounds and is
compatible with lead-free soldering. The ALT series is also
halogen-free and therefore suitable for companies that are
engaged in efforts to completely eliminate halogen from their
end products.
High Performance on a Par with Previous Products Achieved Through Automated Winding
Smaller Footprint Results in Significant Space Saving
Complex manual connecting
line processing has been
replaced by automated
thermo compression
bonding.
ALT series
Thermo compression bonding
of connecting line
Signal quality is on a par with conventional product
Conventional toroidal product
Eye Pattern Evaluation Sample in Ethernet Application
Thermo Compression Bonding of Connecting Line
Comparison of Footprint (100BASE-TX Example)
Pulse transformer (internal, x2)
Common mode choke coil (internal, x2)
SMD pulse transformer
ALT4532M-201-T001(x2)
Common mode filter
ACM2012 (x2)
About 40% reduction
Complex manual connecting
line processing has been
replaced by automated
thermo compression
bonding.
ALT series
Thermo compression bonding
of connecting line
Signal quality is on a par with conventional product
Conventional toroidal product
Eye Pattern Evaluation Sample in Ethernet Application
Thermo Compression Bonding of Connecting Line
Comparison of Footprint (100BASE-TX Example)
Pulse transformer (internal, x2)
Common mode choke coil (internal, x2)
SMD pulse transformer
ALT4532M-201-T001(x2)
Common mode filter
ACM2012 (x2)
About 40% reduction
06
SMD Pulse Transformer for Ethernet Applications
Wireless LAN is becoming more widespread, but wired LAN still
has a clear advantage in terms of high transfer rates, resistance
to interference, and operation stability. Pulse transformers
which are a key component for LAN applications will need
to meet the performance requirements for next-generation
Ethernet solutions.
Servers, routers, and similar equipment must support higher
speeds and provide outstanding reliability, while compact
dimensions and a low-profile form factor are design targets
in notebook computers, digital TVs, hard disk recorders,
game consoles, etc. In the factory automation sector, further
performance improvements under a wide range of temperature
conditions are called for.
Covering the entire spectrum from home use to industrial
applications, the ALT series conforms to high performance
specifications. As an industry first, these compact SMD
type pulse transformers implement automated winding. The
next-generation high-speed networks integrating wired and
wireless connections will demand advanced component
technology. Making full use of its extensive know-how in core
technologies, namely materials technology, process technology,
and evaluation & simulation technology, TDK is offering
sophisticated LAN application products that meet these needs.
Towards Next-Generation High-Speed LAN Integrating Wired and Wireless Connections
07
D D T 2.2max i 2.9mm COMMEND I D PATTE I I I 0 Q 0 9 ‘ ‘ 7 435:: 7 +3 :7 E 2% EB E CI: 9.3%.— +33 22%.— 9743 5 E 4 47+ \ m m b; ’ “” W
SMD Pulse Transformer for Ethernet Applications
ALT3232M
SHAPE & DIMENSIONS SHAPE & DIMENSIONS
RECOMMENDED
LAND PATTERN
CIRCUIT DIAGRAM RECOMMENDED
LAND PATTERN
CIRCUIT DIAGRAM
ALT4532M
Dimensions in mm
3
2
1
4
5
6
3
2
1
4
5
6
3.2±0.252.9max.
3.2±0.25
1
2
3
6
5
4
3.2±0.2T
4.5±0.2
1
2
3
6
5
4
T
2.2max.
2.9max.
0.90.9
1.350.65 0.7
0.41 0.410.41
0.85
1.391.39
1.350.65 0.70
0.41 0.410.5
1.0
Dimensional Drawing and Circuit Diagram
1
2
Major Applications
Major Specifications
Consumer/industrial equipment with LAN interface such as digital home appliances, set-top
boxes, PCs
Major Features
SMD type supporting automated winding, shape can be adapted to customer requirements
Support for automated mounting, reflow soldering, and halogen-free applications
Part No. ALT3232M-151-T001  ALT4532M-171-T001  ALT4532M-201-T001
Inductance    150uH Min.       170uH Min.       200uH Min.
Insertion Loss   2.5dB Max.        2.5dB Max.        1.5dB Max.
Intra-Winding Capacitance
25pF Max.              35pF Max.
Temperature Range for Use
                 -40 to 85℃
Form Factor    3.23.2mm  4.53.2mm
Thickness    2.9mm Max.       2.2mm Max.       2.9mm Max. *1 DC Bias 8mA , 100kHz
*2 0.1 to 100MHz
08
2017.09.05

Products related to this Datasheet

XFRMR LAN 1CT:1CT 200UH
PULSE XFMR 1CT:1CT 150UH
PULSE XFMR 1CT:1CT 150UH
XFRMR LAN 1CT:1CT 170UH
XFRMR LAN 1CT:1CT 200UH
EVALUATION BOARD, PULSE TRANSFOR
XFRMR LAN 1CT:1CT 170UH
XFRMR LAN 1CT:1CT 170UH
XFRMR LAN 1CT:1CT 200UH
PULSE XFMR 1CT:1CT 150UH