B82792C0 [TDK]
General Purpose Inductor,;
| 型号： | B82792C0 |
| 厂家： | 
TDK ELECTRONICS |
| 描述： | General Purpose Inductor, 电感器 |
| 文件： | 总7页 (文件大小：419K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Inductors
Data and signal line chokes
Selection guide, General
Date:
Data Sheet October 2008
EPCOS AG 2008. Reproduction, publication and dissemination of this publication, enclosures
hereto and the information contained therein without EPCOS’ prior express consent is prohibited.
Data and signal line chokes
Selection guide
Surface-mount types
Design
Type
VR
LR
IR
Features
V AC mH
mA
Double chokes
B82788C0/S0 42
B82789C0/S0 42
0.011 … 150 …
I core, EIA size 1210,
for automotive, industrial
and telecom applications
0.1
300
0.011 … 150 …
0.1 300
I core, EIA size 1812,
for automotive, industrial
and telecom applications
B82789*N: Top up to 125 °C
B82789*H: Top up to 150 °C
B82799C0/S0 42
B82793C0/S0 42
0.011 … 200 …
0.47 300
Ring core, EIA size 1812,
for automotive applications
0.005 … 100 …
47 2000
For automotive, industrial
and telecom applications
(LR >4.7 mH only for tele-
com applications), reduced
height, high currents
B82790C0/S0 42
0.005 … 200 …
For automotive and
4.7
1000
industrial applications
B82792C0
B82794C0
42
42
4.7 …
50
100 …
600
For telecom interfaces
and ISDN systems
4.7 …
68
200 …
700
For telecom applications
and RF equipment
Quad chokes
B82793C2
B82792C2
42
42
0.011 … 100 …
2.2 200
For telecom applications
and ISDN systems
0.47 … 300 …
For telecom applications
and RF equipment
4.7
600
B82794C2
42
4.7 …
10
200 …
300
For telecom interfaces
and ISDN systems
Please read Important notes
and Cautions and warnings.
2
10/08
Data and signal line chokes
Selection guide
Leaded types
Design
Type
VR
LR
IR
Features
V AC mH
mA
Double chokes
B82796C0/S0 42
0.005 … 400 …
For automotive
4.7
1200
and telecom applications,
high currents
B82720H15
42
42
4.7 …
68
200 …
700
For telecom applications,
small size
B82791G15/
H15
2.2 …
47
100
For telecom applications,
horizontal and
vertical versions,
good RF characteristics,
without potting
Quad chokes
B82796C2
42
42
0.011 … 100 …
For telecom applications,
small size
2.2
200
B82720H14
4.7 …
10
200 …
300
For telecom applications,
compact design
B82791G14
42
0.2 … 6 100
For telecom applications,
good RF characteristics
Please read Important notes
and Cautions and warnings.
3
10/08
Data and signal line chokes
General
1
Data line choke applications
In the data and signal transmission it is important to ensure electromagnetic compatibility.
■ The number of systems being used for the acquisition, processing and distribution of data is con-
tinuously growing.
■ Microelectronics are spreading into new fields of application (e.g. automotive electronics).
■ The growing popularity of xDSL with its high transmission rates and worldwide networks has led
to new EMC problems.
Until recently the use of shielded cables was the main way of preventing data transmission from
being disturbed by RF interference fields. A more economical solution is the use of symmetrical
transmission line systems. In these, twisted pair lines are used in conjunction with data line chokes.
The chokes used here have extremely good symmetry characteristics.
Z
L = Data line
. . . .
. . . .
Z
L
L
~
choke
Z = Characteristic
impedance
CP
CP
CP = Parasitic
capacitances
SSB1407-X
Diagram showing the principle of a symmetrical
transmission line with data line chokes
2
Technical advantages
The main advantages are the low space requirements even for high inductance values used to
suppress common-mode interference. This is achieved by using bifilar windings, which are more
favorable for producing chokes with excellent symmetry characteristics than other winding designs.
This results in very low stray inductance, a characteristic that is highly desirable for achieving the
lowest possible attenuation of the differential-mode data signal.
Data line chokes suppress common-mode interference coupled into data lines from frequencies as
low as 1 kHz up, whereby they have no effect on data signals with bandwidths of up to several
megahertz.
Note:
To achieve the choke’s function fully, care must be taken to ensure that the vector sum of all
currents flowing through the choke is zero.
Please read Important notes
and Cautions and warnings.
4
10/08
Data and signal line chokes
General
3
Applications
3.1
Interference suppression on data and communication lines
Increasingly high clock frequencies/transfer rates and the associated fast rise times mean that the
signals used in modern data and telecommunications engineering are a serious potential source of
RF interference that can influence other devices and systems. At the same time, electronic data and
telecommunications equipment itself is becoming increasingly compact, which exposes it to the risk
of external conducted and radiated interference. The wide-area networking of telecommunications
equipment presents a special problem, because interference is then also able to propagate over
wide areas. To judge this, it is important to look at the different propagation modes of conducted
interference:
Differential-mode interference (symmetrical):
The effect of differential-mode interference can be kept to a minimum by suitable, balanced design
of the transmission circuit.
One measure of this kind is the use of cables with twisted pairs. Because the conductors are routed
so close together and twisted, coupling in of differential-mode interference through electromagnetic
fields is practically impossible.
Common-mode interference (asymmetrical):
Common-mode interference is caused by electromagnetic fields that induce interference voltages
in lines. It can only be reduced by filtering or shielding.
The most commonly used means of transmission are based on symmetrical data signals routed
over twisted pairs. Examples of this are the analog plain old telephone system (POTS) and new
digital systems like ISDN (integrated services digital network) or high-speed networks like ADSL
(asymmetrical digital subscriber line).
In all such cases, the useful signal appears as a differential-mode signal. As mentioned, the
interference coupled in by electromagnetic fields is in common mode. By appropriate protective
circuitry it is possible to suppress the interference and at the same time let the transmitted
symmetrical signal pass unaffected.
Chokes are a very effective means of protecting data lines. The different designs, optimized for
telecommunications and data applications, exhibit very low stray inductance (approx. 1‰ of rated
inductance) and excellent symmetry features. They can substantially enhance the characteristic
symmetry of a transmission line and thus contribute further to increasing interference immunity and
at the same time reducing emitted interference.
3.2
Automotive electronics
Automotive bus systems like CAN (Controller Area Network) and FlexRay®1) make it possible to
simplify the wiring of a vehicle considerably, enabling the same cable harnesses to be used for
vehicles fitted with different combinations of electrical equipment and appliances. In modern motor
vehicles the CAN bus has evolved as a standard. However, car electronics is a growing field. In the
past there were only a few controllers, e.g. ABS, powertrain, airbag. Nowadays, a lot of new features
for driver assistance and safety applications are already available and this is by no means the end.
1) FlexRay® is a registered trademark of Daimler AG
Please read Important notes
and Cautions and warnings.
5
10/08
Data and signal line chokes
General
The need to reduce CO2 emissions will lead to sophisticated engine management with many
sensors, actuators and control units. Driver assistant systems will continue to grow in the future.
This development was foreseen by major automotive tier 1 suppliers. So, in 2000 a consortium was
founded. The target was to develop an automotive bus system that would fulfill the additional
requirements for future in-car control applications including the combination of higher data rates,
deterministic behavior and the support of fault tolerance. These efforts led to the FlexRay bus. This
is able to handle a data rate of 10 Mbit/s on two channels, meaning a gross data rate of up to
20 Mbit/s.
Both CAN and FlexRay are serial two-wire bus systems that network the various control systems in
an automobile and thus enable these to communicate with each other. Transmission of data is by
a symmetrical signal. Due to asymmetries (see table below) in reality there is no 100% symmetrical
signal possible.
Topic
Reason for asymmetry
Reason for parasitics
Layout of bus signal lines Routing of signal CAN H
(FlexRay BP)
Capacitance and inductance of vias
Routing of signal CAN L
(FlexRay BM)
Termination filters
Connectors
Matching of split termination
Capacitance of resistors to ground
Geometry pad CAN H/CAN L Capacitance and inductance
(FlexRay BP/BM)
of contacts
Printed circuit board
Width path CAN H (BP)
Width path CAN L (BM)
Etching of lines and pads
Soldering of pins
Dielectricity of PCB
These asymmetries can cause EMC problems. On one hand external electromagnetic fields may
couple onto the bus and interfere with the useful signal. On the other hand the bus may radiate
voltages that can interfere with other electronic equipment in the automobile. Neither is desirable
and for safety-relevant applications absolutely forbidden. The solution is specially designed data
line chokes. In general these chokes are quite similar for both: CAN and FlexRay. But due to the
different clock rates the focus is on different parameters.
For both applications it is necessary to achieve high common-mode interference suppression
(asymmetrical attenuation) in a broad bandwidth.
A CAN bus choke may have higher symmetrical attenuation in the megahertz frequency range. In
the CAN bus this is necessary to adequately suppress the differential-mode that is induced due to
this system’s inherent lack of symmetry.
For FlexRay, because of the clock rate up to 10 MHz, this is forbidden. A symmetrical inductance
(stray inductance of common-mode choke) in the megahertz range would influence the useful
signal and lead to a lack in signal integrity. For this the stray inductance must be a minimum.
As a consequence to excellent electrical ratings and especially the very low stray inductance, the
100 µH SIMDAD data line choke (B82789C1104N003, EIA size 1812) was chosen as the reference
type for FlexRay by the EMC working group of the FlexRay consortium. Also the 51 µH was tested
and found suitable for FlexRay.
Please read Important notes
and Cautions and warnings.
6
10/08
Data and signal line chokes
General
Meanwhile the high-temperature series B82789C*H (51 µH, 100 µH) has also been tested by the
Institute of Applied Science in Zwickau, which is responsible for EMC measurements for the
FlexRay consortium. It was demonstrated that the results are nearly the same. These test results
are obtainable.
Subsequent development work on data line chokes finalized in a new SIMDAD 1210 series
(B82788, EIA size 1210). For this series the EMC test reports for CAN and FlexRay are already
available. It can be demonstrated that although size is significantly reduced, performance is quite
similar to the 1812 series.
4
Markings
The markings stamped on the data line chokes are described in the respective data sheets. The
following coding methods are used to mark inductance values and the date of manufacture on com-
ponents:
Inductance values (coded in nH):
Example: 104 = 10 × 104 nH = 100000 nH = 100 µH
Date of manufacture:
On small styles the date of manufacture is coded by four digits, e.g. 8293:
8 = calendar year 2008
29 = calendar week 29
3 = 3rd day of week (Wednesday)
On larger components the month and year are marked, e.g. 06/08 or 06-08 or the date of
manufacture is coded using five digits, e.g. 08293:
08 = calendar year 2008
29 = calendar week 29
3 = 3rd day of week (Wednesday)
Please read Important notes
and Cautions and warnings.
7
10/08
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