In complex communication scenarios, each peripheral system component needs to communicate with the host and other peripheral devices through a reliable communication bus. CAN is undoubtedly an extremely reliable and economical communication scheme that has been recognized by the public. CAN bus is a serial communication bus developed by Bosch company and defined by international standards organization. It has strong fault tolerance and is different from traditional networks. CAN bus does not need to transfer large data blocks between nodes, but adopts short packet mode, which makes the system has better stability.

u Car Communication - Car CAN

With the continuous evolution of automobile structure, the communication mechanism between automobile electronic systems has become complicated. In the past, many systems tended to be local, independent, and unable to communicate information with each other; And now linkage has become the most basic requirement. Especially after the introduction of ADAS function, the amount of data in the car increases, and the requirements for security and real-time are more stringent. In addition, with the addition of ECUs and the safety requirements of intelligent vehicles for more advanced functions, in-car CAN communication can become the mainstream bus.

The vehicle CAN system connects multiple ECUs to a communication line and exchanges data with each other. There are now two types, CAN and CAN FD, depending on the protocol and communication speed. The maximum transfer rate of CAN is 1Mbps, while the maximum transfer rate of CAN FD is 8Mbps. These upgrades may still not be able to meet the growing in-car communication limitations, so there is now a higher speed version - the CAN XL, which has a transfer rate of more than 10Mbps.

This superior communication capability is built on the core CAN interface chip. The CAN interface chip contains a physical layer circuit that is responsible for the physical connection to the CAN bus and the digital/analog conversion. It converts controller output numbers into identification numbers suitable for sending to or from the BUS to the controller.

CAN interface chip design threshold is high, before foreign manufacturers occupied most of the market share. However, in recent years, the rapid technological progress of Chinese local manufacturers has made Chinese CAN interface chips more and more perfect. Such as Sichuan Tuowei, Nanwei, core force, 3PEAK and other manufacturers to provide support CAN/CAN FD interface series chips, excellent performance and characteristics. For example, the sleep/standby mode of the third-generation CAN FD transceiver interface chip to wake up specific frames helps the ECU to maintain a low power state for a long time to reduce the overall power consumption; Based on self-developed SIC(Improved Ringing Suppression) innovative patented technology, it is claimed that it can achieve transmission rates of more than 8 Mbps and further improve information quality through ringing suppression function.

u Transition from CAN to CAN FD electronic components

From CAN to CAN FD, the transmission capacity has been significantly improved, and the interference problem has also begun to emerge. First, high frequency will cause resonance and lead to misjudgment; Second, the radiation frequency band is shifted to high frequency, and the difficulty of EMC processing is increased.

Although CAN FD can support faster speeds, it is often limited to 2Mbps when used. Because resonant effects at high frequencies significantly aggravate interference, the ringing suppression of nanonucleus is an EMI design optimization, even without common-mode induction can still achieve good overall anti-interference performance.

In addition to changing the interface chip design, the common mode filter can also be improved. Specifically, it is to reduce leakage and look for parasitic capacitance. How to modify the winding structure design to minimize the leakage inductance, parasitic capacitance and mode conversion characteristics of the common-mode filter is the key to the application of CAN FD.

u Brief summary

In the future vehicle communication environment, high-speed communication with a larger amount of data is needed, and the communication speed of CAN system is gradually increasing, but at the same time, various interference problems continue to emerge. Solving these problems requires innovative chip designs combined with high-performance electronic components.