Faster data communication in CAN infrastructures

November 04, 2016 // By Christoph Hammerschmidt
CAN FD is starting to complement and, in parts, to replace the venerable CAN bus for in-vehicle data communications. FD stands for Flexible Data Rate and offers not only higher performance but also better transmission reliability. Infineon now has introduced its first CAN FD transceiver product family.

With its TLE925x CAN FD transceivers , Infineon makes data exchange up to 30 times faster than today. The TLE925x reaches transmission speeds of up to 5 Mbps. Compared to the classical plain vanilla CAN transceivers with a maximum payload of 8 byte per data frame, the CAN FD transceivers such as TLE925x can send a payload of up to 64 byte per frame. This opens up the possibility to check the transmitted data for consistency in the transmitting control unit and to sign it with a 21-bit checksum instead of the 17-bit possible so far. Longer checksums ensure reliable communication between the control units. This makes it possible to better secure data transmission in the vehicle without the application software becoming more complex in the electronic control unit.

 

CAN FD transceivers are used, for example, in body control modules and gateways, in power steering, engine and transmission control units as well as in radar and camera-based driver assistance systems. On average, every vehicle today has 17 CAN transceivers. The number should rise to more than 20 within the next five years.

The TLE925x CAN FD transceivers permit an interface voltage to the microcontroller of 3.3 V as well as 5 V for best-possible signal symmetry. The more symmetrical the signals are, the better the electromagnetic compatibility (EMC) is. Compared to the previous CAN generation, Infineon has improved the robustness of the CAN FD transceivers to electromagnetic interference (EMI) in the standard frequency range of 1 MHz to 1 GHz.

The electromagnetic emission (EME) of the TLE925x between 150 kHz and 1 GHz is lower than in any other CAN transceiver available today. At the same time the CAN FD transceivers pass electrostatic discharge tests (ESD) of at least ±8 kV according to IEC61000-4-2.

For the protocol variant CAN FD with 5 Mbit/s, Infineon offers, apart from the TLE925x transceivers compliant to ISO11898-2:2016, the matching system basis chips in