Common-mode chokes ACT45L type for automotive Ethernet
Automatic wire winding provides for excellent mode conversion characteristics
World's smallest common-mode choke for
automotive Ethernet
In order to operate more safely, reduce their impact on the environment or offer increased comfort to the user,
automobiles continue to evolve: in fact, change is constant. This is also the case with in-vehicle electronic
devices - not only car navigation and car audio systems, but also sensor- and camera-based devices are
proliferating as car manufacturers implement equipment such as on-board IVI (In-vehicle Infotainment)
systems and ADAS (Advanced Driver Assistance Systems). This has led to an increasing need for higherspeed in-vehicle LAN systems that connect multiple ECUs (electronic control units). Consequently Ethernet
technology has been introduced at a rapid pace, as an in-vehicle LAN system for advanced multimedia and
data communication devices.
To meet these networks’ need for excellent noise suppression characteristics in a small and low-profile
form (L4.5 x W3.2 x H2.8 mm), TDK offers common mode filters suitable for various in-vehicle LAN systems
including CAN (controller area network) and FlexRay, as well as the ACT45L type of common mode filters for
Ethernet.
Ethernet forecast to be the backbone network for invehicle LANs
CAN is the most common type of network, used mainly in
body systems. It features a maximum data transfer speed of
1Mbps (5Mbps for CAN-FD). On the other hand, the maximum
In-vehicle Ethernet networks are found in various parts of
data transmission speed of FlexRay in powertrain systems is
the automobile: body systems, safety systems, powertrain
10Mbps. However, these in-vehicle LANs have limitations in
systems, and multimedia/information systems. Currently,
20151105
1
Figure 1: Communication speed of each in-vehicle LAN and TDK's common mode filters used as an EMC measure
Body
Power train / x-by-wire
up to
10Mbit/s
CAN(-FD)
●Key,doors
●Seats
●Lights
●Air conditioning
●Dashboard
ACT45B
(1812)
up to
10Mbit/s
FlexRay
●Brakes,ABS
●Electric power
steering
●Transmission
●Engine
ACT1210
(1210)
ACT1210-101
(1210)
Gateway
up to
0.25Mbit/s
Safe-by-wire
DSI bus
BST bus
●Sensors
●Airbags
●Airbag squibs
ACT45B
(1812)
Safety
up to
100Mbit/s
Ethernet
●Cameras
●Video
●Audio
●Navigation
ACT1210
(1210)
IVI
ADAS
●Sensor
●Radar
ACT45L
(1812)
Multimedia/infotainment
The use of Ethernet in-vehicle LANs that connect sensor-related or camera-related electronic devices
for IVI systems or ADAS is becoming more widespread.
terms of data transmission speed and network expandability.
Figure 2: Roles of a common mode filter in in-vehicle Ethernet
By contrast, Ethernet features a higher data transmission
speed of 100Mbps or faster, as well as superior expandability
ECU
as a backbone network, enabling the user to implement an
advanced network architecture. It is now attracting attention
Incident wa
Physical
layer
chip
as an interface for developers who wish to realize IVI systems
or ADAS.
The differential transmission system is generally adopted
PORT1
UTP cable
(unshielded twisted pair cable)
《Common mode filter》
Suppresses radiation noise from the physical layer chip of the ECU,
while protecting the chip from noise entering from the cable.
in in-vehicle LANs, except for LIN and low-speed CAN. The
differential transmission system features low radiation noise
and high immunity against external noise, and is adopted
peripheral devices, such as USB or IEEE1394 interfaces.
Re
b1
DUT (devi
common m
S
The ratio
sion wa
wave (u
An advantage of in-vehicle Ethernet is that inexpensive and lightweight
UTP cables can be used; however, it is important to implement EMC
measures against common mode noise.
widely in high-speed interfaces that connect PCs with
a1
However, the cables of these high-speed interfaces function
as antennas that radiate or pick up noise. For this reason,
common mode filters are used at the connector parts of the
Figure 3: Conceptual diagram of the S parameter (mixed mode) in a 2
terminal pair circuit
interfaces as an EMC measure. Fig. 1 shows the applications
of various in-vehicle LANs and the recommended TDK
Physical
In-vehicle
layer Ethernet
chip
standard from OPEN Alliance SIG
PORT1
UTP cable
(unshielded twisted pair cable)
A common mode filter is an EMC countermeasure component
b2
a1
Reflected wave
PORT2
b1
DUT (device under test):
0
common
mode filter, etc.
Sdd21
modeprevent
filter》
that can《Common
effectively
only the common mode noise
current,
Transmission
wave
Incident wave
Suppresses radiation noise from the physical layer chip of the ECU,
while protecting
the chipthe
fromdifferential
noise entering from
the cable.
without
affecting
mode
signal current.
– 10
– 20
(dB)
However, the interior of an automobile is a noisy environment
due to the strong magnetic fields induced in cables carrying
large currents, inductive noise caused by motors, etc., and the
instantaneous burst noise caused by the ignition plug. This
1/10
1/1000
– 40
1/10000
– 60
1
for in-vehicle Ethernet with characteristics that are far better
|S21|
The ratio of the transmission wave to the incident
– 30
wave (unit: dB)
– 50
has led to a requirement, therefore, for common mode filters
S21=b2 /a1
The differential
mode components
pass through while
hardly
being
20log
10|S21|
blocked.
20dB
Scc21
10
100
Frequency (MHz)
1/100
40dB
The common
60dB
mode
components
are
80dB
significantly
blocked at around
10 to 100 MHz.
1000
than those of existing products.
transmission system when using UTP (unshielded twisted
for in-vehicle Ethernet are standardized as "BroadR-Reach"
manufacturers to the use of inexpensive and lightweight UTP
Ethernet network may achieve high performance with a
weight of the wire harness and contribute to reductions in both
The characteristics requirements of common mode filters
pair) cables. There is a big advantage for automobile
by the OPEN Alliance SIG, a standards body. An in-vehicle
cables , because they can significantly reduce the length and
data transmission speed of 100Mbps through the differential
weight and fuel consumption.
– 10
)
– 20
Sdd21
The differential
mode components
pass through while
hardly being
blocked.
–0
– 20
2
21 (dB)
0
– 40
In-vehicle Ethernet standard (Limit Class B)
Common mode filter for CANs
Common mode filter for in-vehicle Ethernet ACT45L
Common mode filter
for CANs
20151105
d: Differential mod
c: Common mode
s: Single end
Signal mode on the
Signal mode
– 0 on th
– 20
The ratio o
– 40
components
converted iC
components
– 60
(unit: dB)
Scd21 (dB)
common
ECUmode filters that are used in these LANs.
– 80
–100
1
ECU
a
Transmission
UTP cable
wave
(unshielded twisted pair
cable)
b2
ECU,
g |S21|
The ratio of the differential mode
S21=b2 entered
/a1
components
from PORT 1
converted into the common mode
Thecomponents
ratio of the transmisand output to PORT2
sion
wave
(unit:
dB)to the incident
10
40dB
60dB
wave (unit: dB)
80dB
|S21|
20log10|S21|
1/100
40dB
1/1000
60dB
1/10000
80dB
0
– 10
0
mode components
S parameter stands for
the "scattering parameter,"
and
Sdd21
pass through while
(dB)
blocked.
– 20
of reflection
or transmission of the wave when capturing
–0
(dB)
mode
mode filter for CANs
components
Fig.– 20
3 is– 40a Common
conceptual
diagram of the S parameter
(mixedare
Common mode filter for in-vehicle Ethernet ACT45L significantly
are
round
Hz.
Scd21 (dB)
Common
mode filter
circuit).– For
the sake
of simplicity, only transmission in the
60
1000
1
Improvement
is transmitted
to port 2
– 80
by approx. 30dB
The differential
mode components
pass through while
hardly being
blocked.
The common
mode
components are
ACT45Lsignificantly
for Ethernet
blocked at around
10 to 100 MHz.
Common mode filter
for CANs
Scc21
Improvement
by approx. 30dB
– 80
– 60
1– 100
10 to 100 MHz.
– 60
forward
direction is
n
– 30 – 40
– 50
mode S– 50
parameter) inScc21
a 2 terminal pair circuit (4blocked
terminal
at around
100
explained.
Incident
)
Frequency (MHz
suppressed the generation of
common
1000 mode noise.
In-vehicle Ethernet standard (Limit Class B)
Common mode filter for CANs
Common mode filter for in-vehicle Ethernet ACT45L
– 40 – 60
– 30 In-vehicle
common
alternating
signalsEthernet
flowing
through
the circuit
as The
waves.
standard
(Limit Class
B)
for CANs 10
The common
40dB
mode
components
are
1/1000
60dB
significantly
1/10000
80dB
blocked at around
The lower Scd21 is, the more
10 to 100 MHz.
1/100
Sdd21
–0
– 20 – 20
– 10
hardly
being
expresses the circuit characteristics based on the
degree
1
Portblocked.
No. on the input side
20log10|S21|
Port No.
20dBon the output side
1
1000
wave a1 from PORT
10
100
10(MHz)
Frequency
Frequency (MHz)
1000
100
1000
ACT45L for Ethernet
as b2; however, part of it is reflected
and returned to PORT 1. The ratio of transmission wave b2 to
– 100
incident
by parameter
1 wave a1 at this
10 point is expressed
100
1000 S21.
Frequency (MHz)
This parameter is nearly equivalent to the insertion loss of
filter characteristics, and is generally expressed in units of dB
(decibels). The notation of 21 expresses the transmission from
PORT 1 to PORT 2 (2 <- 1).
a comparison of mode conversion characteristics between
In common mode filters for in-vehicle Ethernet, the parameter
an existing product for CANs and the ACT45L type; the red
called the mode conversion characteristic is important (Fig. 4).
solid line shows the characteristics requirements for in-vehicle
For example, the typical mode conversion characteristic
Ethernet (Class A). When the characteristics curve is at the
Scd21 expresses the amount of mode conversion from the
lower part of the graph, it shows that it is more difficult for
differential mode (d) components to the common mode (c)
signals (differential mode) to be converted into common mode
components in transmission from PORT 1 to PORT 2. To
noise, i.e. the product has a good characteristic as a common
put it simply, the smaller Scd21 becomes, the smaller the
mode filter.
proportion of the signal current (differential mode components)
The figure shows that, in the ACT45L type, the characteristic
that is converted into the common mode component, thus
is improved approximately by 30dB in a wide frequency
suppressing the generation of common mode noise.
range compared to that of the existing product for CANs, and
the series exceeds the strict characteristics requirements
Easily satisfies the characteristics requirements of invehicle Ethernet
for in-vehicle Ethernet by a wide margin. Moreover, all the
production processes for the ACT45L type are completely
An example of the frequency characteristics of TDK's ACT45L
automated, which ensures the product offers consistently
in Fig. 5. It is clear from Figure 5 that the common mode
unique winding design and is produced with a high precision
100MHz (Scc21), whereas the differential mode components
mode conversion characteristics while maintaining a high
type common mode filters for in-vehicle Ethernet is shown
high quality and high reliability. The series also features a
components are substantially blocked at around 10MHz to
automatic winding system, which enables it to offer excellent
pass through with hardly any attenuation (Sdd21). Fig. 6 is
inductance value of 200μH (at 100kHz) despite its small, low
profile 4532 size.
20151105
3
a
b
d: Differential m
c: Common mod
DUT (d
s: Single end
commo
Signal mode on t
–0
Signal mode on
– 20
The r
sion
– 40 ratio
wave
The
componen
converted
– 60
componen
(unit: dB)
– 80
– 100
1
Figure 6: Comparison of mode conversion characteristics between an
existing product and the ACT45L type
characteristics or signal quality in in-vehicle Ethernet.
The
The differential
– 40
1/10
– 30 The ratio of the transmission wave to the incident
Ex.: Scd21
– 40 wave (unit: dB)
The ratio of the differential
mode
Scc21
– 50
components
entered from PORT 1
converted into the common mode
– 60
components
and output
to PORT2
1
10
100
(unit: dB)
Frequency (MHz)
The lower Scd21 is, the more
suppressed20dB
the generation of
1/10
common mode noise.
The S parameter is used as a measure of the noise
or Ethernet
|S21|
S21=b2 /a1
– 20
Signal mode on the input side
Mode conversion characteristics of a common mode filter
for in-vehicle Ethernet
al
nents
while
hardly being
Signal mode on the output side
DUT (device under test):
common mode filter, etc.
Ex.: Scd21
20dB
S
– 10
PORT2
radiation
noise from the physicalPort
layer
of the
Signal mode
on the output
side
No.chip
on the
inputECU,
side
b1 Suppresses
while protecting the chip from noise entering from the cable.
Signal mode on the input side
Port No. on the output side
)
b2
–0
– 20
Scd21 (dB)
PORT2
c: Common mode
s: Single1《Common
end
PORT1
mode filter》
Reflected wave
(dB)
b2
S
Incident
wavemode
d: Differential
a1
Reflectedfilter》
wave
PORT2
《Common
b1 mode
Suppresses
radiation noise from the physical layer chip of the ECU,
d: Differential
mode
The
differential
while
protecting the chip from noise entering from the cable.
0
DUT
(device under test):
mode components
c: Common
mode
Sdd21
mode filter,
etc.
pass through while
s: Singlecommon
end
Scd21 (dB)
Transmission
wave
Transmission
UTP cable
wave
(unshielded twisted pair cable)
Incident wave
PORT1
PORT1
Scd21 (dB)
ECU
Figure 4: Notation for the mode conversion characteristics
Physical
layer
chip
Incident
Physical
layer
chip 5: Frequency characteristic example of ACT45L
Figure
– 40
– 60
– 80
– 100
1
support safe and comfortable driving. TDK has developed the
Summary
ACT45L type of common mode filters for in-vehicle Ethernet
systems, taking advantage of the ferrite, winding and design
technologies that it has developed over a long period of time.
Since Ethernet allows for high-speed transmission of large
TDK will continue to enhance its line-up of miniature common
amounts of data, it has been adopted at a rapid pace in
mode filters for in-vehicle LANs, which includes the existing
in-vehicle LANs, where it may be used to transmit high-
ACT45B/ACT45R types supporting the CAN standard and the
quality video images through on-board cameras, etc., and to
ACT1210 type supporting the CAN and FlexRay standards.
Main features, applications and electrical characteristics of the ACT45L type
《Main applications》
《Main features》
● Small
and low profile (mounting area: 4.5 x 3.2mm, height: 2.8mm)
● Achieves
An EMC measure in in-vehicle Ethernet systems for communication of
an excellent mode conversion characteristic Scd21 while
video images from on-board cameras, or audio signals
offering a high inductance value of 200μH, owing to TDK's unique winding
technology and high precision automatic winding system
ensures high quality and reliability thanks to wholly
automated production processes
● Consistently
● Solderless
● Conforms
● Conforms
design
to AEC-Q200
to RoHS directive and supports pb-free soldering
Main electrical characteristics
Product name
ACT45L-201-2P-TL000
Common mode inductance
at 100kHz[μH]typ.
DC resistance
[Ω]max.
Rated current
[mA]max.
Insulation resistance
[MΩ]max.
Rated voltage
[v]max.
200
4.5
100
10
50
20151105
4