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Application Note
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Application Note
In conjunction with advances in automotive technology, it is become necessary to quickly convey large volumes of data, and increasing the speeds of automotive networks has become increasingly important. Compared to earlier automotive networks, automotive Ethernet makes it easy to optimize and simplify the applications and networks that are desirable for increasing the speed of data transmission. In addition, in conjunction with increases in automotive network communication speeds, signal quality and EMC countermeasures have become more important, and as a result, it is necessary to select common mode filters/chokes that comply with the OPEN Alliance standards.This document describes TDK's ACT1210L series of common mode filter/choke for automotive Ethernet use. 

Automotive Ethernet

The OPEN (One-Pair Ether-Net) Alliance Special Interest Group (SIG) recommends the 100BASE-T1 and 1000BASE-T1 standards for automotive Ethernet. In this document, we present radiated EMI, conducted EMI, and BCI results for the ACT1210L-201, which complies with the OPEN Alliance 100BASE-T1 standards, and the ACT1210-110, which does not comply with those standards, common mode filters/chokes.

Comparison of S Parameter

"Figure 1 shows a comparison of the ACT1210-110 common mode filter/choke for CAN-BUS use with the ACT1210L-201 common mode filter/choke for automotive Ethernet use as an example.
It can be seen that compared to the ACT1210L-201 common mode filter/choke for automotive Ethernet use, the ACT1210-110 common mode filter/choke for CAN-BUS use cannot satisfy the OPEN Alliance standards."

Figure 1

Comparison of Radiated EMI

Noise suppression effects can be achieved by using a common mode filter/choke. In particular, the effect of attenuating the portion that exceeds the standard line at 30 MHz and higher to near the noise floor can be obtained. (Figure 2) The ACT1210L-201 common mode filter/choke for automotive Ethernet use has a greater noise suppression effects than the ACT1210-110 common mode filter/choke for CAN-BUS use around the range of 10 Hz to 40 MHz.

Emission Test for 100BASE-T1 (Automotive Ethernet)

Figure 2
Setup
Status
・Class: CISPR25 Ed3 class 5
・Test site: Anechoic chamber (3m)
・DUT: 100BASE-T1 EVB
・Cable length: 1.5 m

Comparison of Conducted EMI

"Noise suppression effects can be achieved by using a common mode filter/choke. In particular, noise Is suppressed in the portion over the standard around the range of 40 Hz to 90 MHz. (Figure 3)
In the range of 150 kHz to 70 MHz, the ACT1210L-201 common mode filter/choke for automotive Ethernet demonstrates greater noise suppression effects."

Figure 3
Setup
Status
・Class: CISPR25 Ed3 class 5
・Test site: Anechoic chamber (3m)
・DUT: 100BASE-T1 EVB
・Cable length: 1.5 m

Comparison of BCI Results

Setup
Status
・Frequency: 1 - 400 MHz (CW)
・Injection Current: 200 mA (closed-loop method)
・Decision: CRC Error
・Test site: Shield room
Table 1
Frequency MHz Through ACT1210-110 ACT1210L-201
1.00 Fail Fail Pass
1.20 Fail Fail Pass
1.44 Fail Fail Pass
1.73 Fail Fail Pass
2.07 Fail Fail Pass
2.49 Fail Fail Pass
2.99 Fail Fail Pass
3.58 Fail Fail Pass
4.30 Fail Fail Pass
5.16 Fail Fail Pass
6.19 Fail Fail Pass
7.43 Fail Fail Pass
8.92 Fail Fail Pass
10.70 Fail Fail Pass
12.84 Fail Fail Pass
15.41 Fail Fail Pass
18.49 Fail Fail Pass
20.00 Fail Fail Pass
21.00 Fail Pass Pass
22.05 Fail Pass Pass
23.15 Fail Pass Pass
24.31 Fail Pass Pass
25.53 Fail Pass Pass
26.80 Fail Pass Pass
27.00 Fail Pass Pass
28.14 Fail Pass Pass
29.55 Pass Pass Pass
31.03 Fail Pass Pass
32.58 Fail Pass Pass
34.21 Fail Pass Pass
Frequency MHz Through ACT1210-110 ACT1210L-201
35.92 Fail Pass Pass
37.71 Fail Pass Pass
39.60 Fail Pass Pass
41.58 Fail Pass Pass
43.66 Fail Pass Pass
45.00 Fail Pass Pass
45.84 Fail Pass Pass
48.13 Fail Pass Pass
50.54 Fail Fail Pass
53.07 Fail Fail Pass
55.72 Fail Pass Pass
58.51 Fail Fail Pass
61.43 Fail Pass Pass
64.50 Fail Pass Pass
67.73 Fail Pass Pass
69.81 Fail Pass Pass
71.11 Fail Pass Pass
74.67 Fail Pass Pass
78.40 Fail Pass Pass
82.32 Fail Pass Pass
86.44 Fail Pass Pass
90.00 Fail Pass Pass
90.76 Fail Pass Pass
95.30 Fail Pass Pass
100.06 Fail Pass Pass
105.07 Fail Pass Pass
110.32 Fail Pass Pass
115.84 Fail Pass Pass
120.00 Fail Pass Pass
121.63 Fail Pass Pass
Frequency MHz Through ACT1210-110 ACT1210L-201
127.71 Fail Pass Pass
134.10 Fail Pass Pass
140.80 Fail Pass Pass
147.84 Fail Pass Pass
155.23 Fail Pass Pass
162.99 Fail Pass Pass
171.14 Fail Pass Pass
179.70 Fail Pass Pass
188.69 Fail Pass Pass
190.00 Fail Pass Pass
198.12 Fail Pass Pass
198.12 Fail Pass Pass
208.03 Fail Pass Pass
218.43 Fail Pass Pass
229.35 Fail Pass Pass
240.82 Fail Pass Pass
252.86 Fail Pass Pass
265.50 Fail Pass Pass
278.77 Fail Pass Pass
280.00 Fail Pass Pass
292.71 Fail Pass Pass
307.35 Fail Pass Pass
322.72 Fail Pass Pass
338.85 Fail Pass Pass
355.79 Fail Pass Pass
373.58 Fail Pass Pass
380.00 Fail Pass Pass
392.26 Fail Pass Pass
400.00 Pass Pass Pass

TDK's Common Mode Filters/Chokes Compatible with Automotive Ethernet

As automotive common mode filters/chokes compatible with automotive Ethernet, TDK has common mode filters/chokes for 100BASE-T1 and 1000BASE-T1 use compliant the OPEN Alliance standards.

Compliant Standard Product Name
100BASE-T1 ACT1210L-201-2P-TL00
1000BASE-T1 ACT1210G-800-2P-TL05

Summary

"As can be seen from the EMC measurement results, common mode filters/chokes that are not designed for automotive Ethernet have poor EMI noise suppression and BCI immunity. As a result, if a common mode filter/choke that does not pass the OPEN Alliance standard is used, noise may be radiated and interfere with radio and so on, which may have an impact on other communications. In addition, the Sdd21 characteristic of the S parameter has a waveform quality, the Scc21 characteristic has an EMC suppression effect, and the Ssd21 (DCMR) characteristic is a parameter that affects BCI resistance.
Therefore, in conjunction with increases in automotive network communication speeds, signal quality and EMC countermeasures have become more important, and as a result, it is necessary to select common mode filters/chokes that are compatible with DCMR (Ssd21), Which is a mode conversion characteristic, while ensuring a high inductance value that complies with S parameter standards such as the OPEN Alliance standards."