Electromagnetic Compatibility And Quality Verification Of Electronic Components Required For Automotive Systems

Abstract: The automotive component migrates from mechanical to electronic in the automotive application so that more and more electric components are designed in automotive system. Therefore, the EMC issue should be seriously considered in automotive system design. That is not only the issue for the design of system but also involves the EMC performance of electronic component. If the electric component passed the related EMC testing, the robust system design would be a piece of cake. In this article, the EMC evaluations for CAN transceiver of the automotive application will be introduced to reader.

1 Foreword

In the 1980s, the smart and humanized automobiles began to use electronic technology to replace the old design. The ever-changing technology made the car popular and the purchase barrier low. Hence, it is extremely important to ensure that the electronic components used are stable and highly reliable in the development of automotive-related wafers. At present, the AEC certification mechanism (Automotive Electronics Council) can be used to verify the parts qualification and quality system standards. The purpose is to confirm that the electronic components are suitable for automobiles in the harsh environment that not only strictly checks the tolerance and reliability of the products, but also ensures that the requirement of the vehicle specification of 0 ppm is met. In order to ensure that the quality of the wafer can reach the automotive grade standard, the manufacturer of the wafer must be an IATF 16949-certified wafer and packaging test manufacturer, and then the commissioned manufacturing company will carry out a series of verifications based on the corresponding requirements of AEC-Q100.   

The CAN bus transceiver AZCAN1042T (met ISO 11898-2:2016) provided by AMAZING Microelectronic Corp. supports CAN FD protocol speeds up to 2Mbps, and its SO8 package is compatible with the most current automotive specifications. The AZCAN1042T meets AEC-Q100 certification and can achieve a temperature range of Automotive Grade level 0 (-40°C to +150°C). Its production is from manufacturers with IATF 16949 qualification certification to conduct the most stringent verifications so as to ensure that the device is soundly used in the automotive environment.

2.1 Chip operation mode and basic verification

The AZCAN1042T CAN bus transceiver provides two modes of operation, one for normal mode and the other for Standby mode. When entering the standby mode, the current consumption is only ten micro amps, and then bus wakeup determination circuit of the chip (Low Power Receiver (LP_RX) + Wake-up filter) detects the CAN bus behavior to determine whether to wake up the main control circuit, as following Figure 1 shows. The CAN transceiver itself also provides a variety of fail-safe protection mechanisms, such as preventing CAN bus from being used abnormally, power supply low voltage detection, and chip over-temperature shutdown protection (Thermal Shutdown).

Figure 1

The basic verification of the AZCAN1042T by AMAZING Microelectronic Corp. include electrical functional test and reliability test. Respective elaborations are as follows:       

ａ. The electrical test includes the following items in Table 1

b. The reliability test refers to the AEC-Q100-REV-H version, and the items are as shown in Table 2 below.

Table 2

2.2 Electromagnetic compatibility (EMC) related testing

In addition to the basic functional test, the AZCAN1042T CAN bus transceiver is validated against the following EMC test items. The items included are as follows in Table 3:

Table 3

2.2.1 ESD Electrostatic test

Referring to the IEC 61000-4-2 standard, the CAN transceiver is directly soldered to the Demo board, and the reference ground of the wafer is common grounding with the electrostatic gun for testing. The contact discharge test and air discharge test were carried out for the shortest distance of the AZCAN1042T single pin (CANH & CANL). The schematic diagrams are shown in Figure 2 below.

Figure 2. Contact/Air discharge test

2.2.2 ISO 7637: Test pluses 3a&3b

The AZCAN1042T CAN transceiver can be subject to interference from mechanical switches when operating in an automotive environment. This interference characteristic is affected by the capacitance and inductance of the harness distribution. The TXD pin of the left EV board in the figure 3 below is the input waveform (refer to the yellow signal waveform), the RXD pin on the right is the output signal (refer to the green signal waveform). Bus utilizes DCC with ISO7637 pulse 3a&3b interference source. Observe the waveform of  RXD pin.

Figure 3

Figure 4 shows the difference between AZCAN1042T and a manufacturer. It is confirmed that AZCAN1042T can still transmit data normally under the strong interference of the bus in the harsh environment of the vehicle, allowing the system to increase the anti-interference ability and increase its robustness.

Figure 4

2.2.3 IEC 61967-4 Measurement of conducted emissions

IEC 61967 is an electromagnetic radiation test standard for integrated circuits, and is a test method that uses direct coupling between the DUT and a source device. The IEC 61967-4 frequency is from 150 kHz to 1 GHz, and the characteristics of the electromagnetic radiation measured by direct coupling at different transmission rates (500 kbps vs. 2 Mbps) are compared in the test as shown in Figure 5.

Figure 5

2.2.4 EN 55022 Radio disturbance characteristics measurement

The international standard EN 55022 is a radio interference characteristic limit and measurement method for Information Technology Equipment (ITE). The standard is divided into Class A ITE and Class B ITE. The self-designed circuit can refer to Figure 6 and the relevant data can be tested through the third-party laboratory. As shown in Figure 7, the AZCAN1042T meets the limit requirements of Class B ITE.

Figure 6

Figure 7

3 Conclusion

The AZCAN1042T CAN bus transceiver of AMAZING Microelectronic Corp. has passed the AEC-Q100 certification. Through the electromagnetic compatibility test standards mentioned in this paper, the AZCAN1042T can meet the electromagnetic compatibility level that the ECU system unit needs to pass. This electromagnetic compatibility test solution allows system developers to properly evaluate the capabilities and the feasibility of introduction of the device in the relevant test project and reduce the system development time when introducing the CAN bus transceiver.

Reference

◎Order No. 12 of 2012, “Regulations on Compulsory Scraping of Motor Vehicles”, Ministry of Commerce, Development and Reform Commission, Ministry of Public Security, Ministry of Environmental Protection http://www.mofcom.gov.cn/article/b/d/201301/20130100003957.shtml

◎The economic life of the car, Yang Guangwen. Jiaotong Dictionary: Shanghai Jiaotong University Press, Baidu

◎IEC 61000-4-2, EMC - Part 4-2 : Testing and measurement techniques - Electrostatic discharge immunity test, International Electrotechnical Commission (IEC)

◎IEC 61000-4-4, EMC - Part 4-4 : Testing and measurement techniques -

Electrical fast transient/burst immunity test, International Electrotechnical Commission (IEC)

◎ISO 7637-2, Road vehicles - Electrical disturbances from conduction and coupling - Part 2 : Electrical transient conduction along supply lines only, International Organization for Standardization (ISO)

◎IEC61967-4, Integrated circuits - Measurement of electromagnetic emissions, 150kHz to 1GHz - Part 4 : Measurement of conducted emissions; 1Ω/150Ω direct coupling method, International Electrotechnical Commission (IEC)

◎EN 55022, Information technology equipment - Radio disturbance characteristics - Limits and methods of measurement,