CAN FD transceiver
Several chipmakers have qualified CAN high-speed transceivers for data-rates up to 2 Mbit/s. Transceiver supporting higher speeds (4 Mbit/s or 5 Mbit/s) are under development or have been pre-announced.
IN GENERAL, ALL TRANSCEIVERS compliant to ISO 11898-2/5/6 can be used for CAN FD for dataphase bit-rates up to 1 Mbit/s. Last year, NXP was the first company to qualify its Mantis chips for 2-Mbit/s transmission rates. In the meantime Freescale, Microchip, ON Semiconductor, and Texas Instruments have introduced similar products. The main issue is the symmetry of the rising and the falling edges, which required above 1 Mbit/s.
Electromagnetic compatibility (EMC) and electrostatic discharge (ESD) are critical requirements in harsh industrial and automotive environments due to the close proximity of a wide range of networked electronic systems and devices. This means CAN FD compliant transceivers need to meet automotive EMC requirements (± 6 kV ESD and > 36 Bm DPI) without external noise filtering.
Freescale has launched choke-less CAN transceivers - MC33901 and MC34901 -which deliver EMC performance and ESD robustness without the need for external components. The chips also offer fail-safe features to assist with system functional safety, as well as currents down to 8 A. Both products offer performance at 2 Mbit/s to address CAN FD application requirements.
Microchip claims that its MCP2561/2FD transceivers are suitable for data-rates up to 8 Mbit/s. The maximum propagation delay is 120 ns and the loop-delay symmetry is ±10 % for bit-rates up to 2 Mbit/s. The chips comply with ISO 11898-2 and ISO 11898-5 (low-power capability).
The SN65HVD26X series of CAN high-speed transceivers from Texas Instruments is now also specified for bit-rates up to 2 Mbit/s. The chips are characterized for -40 °C to +125 °C operation. The ESD protection exceeds ±12 kV. The SN65HVD267 adds features allowing redundant and multi-topology networks with fault indication for higher levels of functional safety.
ON Semiconductors has also evaluated its CAN transceivers to run at higher bit-rates. The company cooperates with Cast to offer a CAN FD soft IP core, which has been implemented by the IPMS Fraunhofer institute in conjunction with an 8-bit micro-controller (8051).
Bosch is developing its own CAN FD suitable transceiver chips. First datasheets were distributed at the last international CAN Conference in Paris. Infineon will also provide CAN transceivers for CAN FD.
8051 module for CAN FD transceiver evaluation
ON Semiconductor engineers in Brno (Czech Republic) have selected the CAN FD soft IP core by Cast (USA) for evaluation and test purposes. The CAN transceiver manufacturer wanted to qualify its products for higher bit-rates than 1 Mbit/s.
The CAN FD core was integrated into the Talos FPGA together with an 8051 micro-controller. “Not only did Cast have the CAN FD controller and working subsystem board before anyone else, their long experience with CAN IP and reputation for great support and service made our decision easy, really jumpstarting our early transceiver development project,” said Roman Buzas, application manager for IVN (in-vehicle network) products at ON Semiconductor. The CAN and CAN FD controller core used in the Talos 8051 Reference Design Board comes with development software.
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