ZXCOMPO: Murata Common Mode Choke Coil for High Frequency Noise in Automotive Applications
In recent years, with the improvement of ADAS (Advanced Driving Assistance System) accuracy, the automotive industry has begun to install a large number of high-speed sensing equipment such as millimeter wave radar and LiDAR. If noise enters these devices from the outside, the system may not function properly. On the contrary, if these devices generate noise, it may adversely affect other devices, so noise countermeasures are very important.
In April 2023, Murata launched Murata’s first 3225 size wire-wound common mode choke coil for power lines that supports high current (maximum 1.2A) and wide frequency band for automotive applications.
1. Current status of noise reduction countermeasures for vehicle power lines
The automotive market is continuously expanding the applications of ADAS, autonomous driving, V2X, in-vehicle information systems, etc. Since such applications process huge amounts of information, the processing speed of internally processed signals is constantly increasing in order to perform the processing.
On the other hand, as the number of components increases and the mounting density increases, components are required to be miniaturized. In addition, as wireless communication applications that enable high-speed information communication expand, there is a need to deal with higher-frequency noise.
Common mode choke coils can effectively reduce noise radiated from power lines. In the past, the main noise reduction target for automotive equipment power lines was to target AM and FM band frequencies, so large components were used to deal with low-frequency noise. However, with the rapid development of in-vehicle equipment, high-frequency noise reduction countermeasures higher than the AM and FM frequency bands are required.
Common mode choke coil product series used for power line noise reduction measures
In response to the above-mentioned development trends, Murata Manufacturing Co., Ltd. has completed the common mode choke coil for power lines that is suitable for compact high-frequency noise reduction measures.
Below we will introduce the effect of this wire-wound common mode choke coil noise reduction countermeasure, and explain some key factors in substrate design.
2. Radiated noise reduction effect of common mode choke coil
In the measurement system described below, we measured the noise radiated from the EUT using the power cable as an antenna, and clarified the effect of noise reduction using a common mode choke coil.
Measurement system: based on the international vehicle noise control standard CISPR25
The EUT measured this time produced noise in the range of 200MHz-800MHz, but by inserting the common mode choke coil DLW32PH122KX2, the noise in this range was greatly reduced.
The figure below shows the evaluation results of the noise reduction effect of radiated noise:
Noise evaluation results (vertical polarization wave, AVE detection)
3. Noise reduction effect of common mode choke coil BCI test
The BCI test is a test to verify resistance to external noise.
If external noise enters, it may cause the EUT to malfunction. If the noise immunity is poor, even a small amount of noise can cause malfunctions. This test demonstrates the degree of improvement that can be achieved by inserting a common mode choke coil product.
Measurement system: Measurement was carried out in accordance with the BCI test replacement method stipulated in the international automotive noise control standard ISO11452-4.
In the EUT measured this time, after noise of 360 to 400 MHz was injected, the DC/DC converter switching stopped, causing the output voltage to malfunction to become 0V. By inserting a common mode choke coil product, the noise in this range is greatly reduced and the noise tolerance against malfunctions is improved (picture below).
After inserting the common mode choke coil product, no malfunction will occur and the current will be introduced.
The common mode choke coil product DLW32PH122XK2 is a 3225-size small, innovatively developed by Murata by combining its unique winding and bonding technology, structural design optimization and material technology, and can operate from tens of MHz to several GHz with one component. A wire-wound common mode choke coil that implements noise countermeasures in a wide frequency range and supports power lines with a rated current of up to 1.2A. It will be commercialized in April 2023.
4. Summary
Among the noise reduction measures for in-vehicle equipment, noise reduction measures in the AM/FM band have been sufficient in the past. However, in recent years, with the continuous advancement of in-vehicle equipment, it is required to eliminate noise of hundreds of MHz.
Offering a wide range of common mode inductors, Zxcompo is a reliable common mode inductor manufacturer to meet your specific needs. Please contact us now: sales@ZXcompo.com
