In-Vehicle Ethernet and Quality Standards | NEXTY Electronics, an electronic components and semiconductor trading company

In the automobile market, next-generation vehicles, including electric vehicles and hybrid vehicles, are becoming more popular.
As of 2017, next-generation vehicles accounted for 31.7% of new car sales in Japan. This has led to increasing sophistication of ECUs and an increase in the average CEU per vehicle. By handling minute analog signals and high-frequency digital signals, devices can become both a source of noise interference and a target of interference. Devices used in automotive environments must meet stricter electromagnetic compatibility (EMC) requirements than devices used in other environments.

Electromagnetic Compatibility

Electromagnetic compatibility (EMC) is a standard that relates to electromagnetic immunity, i.e., not being affected by the electromagnetic emissions of other systems, and not causing electromagnetic interference to other systems through one's own electromagnetic emissions. The former is called electromagnetic susceptibility (EMS), and the latter is called electromagnetic interference (EMI).

How Electromagnetic Interference Works

Any electronic device can be both a source of interference and a victim of interference. Electromagnetic interference occurs through inductive or magnetic fields in the coupling path. Fields can also be further subdivided into long-distance radiation and short-distance induction, the latter of which can be inductive due to magnetic fields or capacitive due to electric fields. These four types of electromagnetic noise can coexist and simultaneously interfere with equipment.

Current-induced noise

Unintended signal energy, mainly high-frequency noise, is transmitted to equipment via CABLES. FILTERS can be used to prevent this noise.

Noise from the field (long distance)

Mobile phones and other devices that communicate using electromagnetic waves transmit noise to devices. This can easily affect circuits that have ANTENNAS operating at the relevant frequencies. However, the noise energy is usually significantly smaller than the automotive test standard values.

Noise from the field (near field)

The faster the field changes, the higher the frequency, and the closer the distance, the greater the effect of noise.
Capacitive noise is noise caused by an electric field that occurs between your own conductors and the conductors of other adjacent systems, and sources of interference generally include high-voltage lines and communication transceivers.
Inductive noise is noise caused by magnetic fields generated by currents flowing from an interference source system, typically a radio frequency transmitter.

For Ethernet, noise can be prevented by using shielded CABLES, twisting CABLES, and increasing the distance between CABLES that may be subject to interference. For automotive Ethernet, relatively low-cost unshielded Ethernet is preferred.

Quality standards for noise

EMC testing

There are many EMC standards, including not only ISO standards but also domestic standards, standards used by each country, and standards unique to automakers. In the automotive industry, the standards adopted by each automaker vary. Corresponding tests are conducted at the semiconductor level, ECU level, and vehicle level.
The test method for immunity is the direct power injection (DPI) method, and the test method for emissions is the 150 Ω method. Both of the above tests for 100BASE-T1/1000BASE-T1 automotive Ethernet are included in the Open Alliance EMC test specifications. For more information on the Open Alliance, see Technical Column: What is the Open Alliance?

Technical column: What is OpenAlliance?

OTHERS quality standards

AEC-Q100

AEC-Q100 is a quality standard that specifies stress test requirements based on failure mechanisms for integrated circuits (ICs). The AEC (Automotive Electronics Council) is an organization established with the aim of establishing common component qualification and quality system standards. AEC-Q100 is further subdivided and describes test methods, etc.

standard	Content
AEC－Q100－001	Wire Bonding Shear Test
AEC－Q100－002	Human Body Model (HBM) Electrostatic Discharge Test
AEC－Q100－003	Machine Model (MM) Electrostatic Discharge Test
AEC－Q100－004	IC latch-up test
AEC－Q100－005	Non-volatile memory programming / erasure endurance / data retention / service life testing
AEC－Q100－006	Electrically and thermally induced parasitic gate leakage testing
AEC－Q100－007	Failure simulation and test grading
AEC－Q100－008	Early failure rate (ELFR)
AEC－Q100－009	Power Distribution Evaluation
AEC－Q100－010	Solder shear test
AEC－Q100－011	Charged Device Model (CDM) Electrostatic Discharge Test
AEC－Q100－012	Short-circuit reliability characteristics of smart power devices (for 12V systems)