A properly terminated CAN bus is terminated at each end with the characteristic impedance of the cable, this is typically 120Ω on each end for a 60Ω load on the CAN driver. The 60Ω–60Ω split termination is preferred to reduce high-frequency noise and common-mode drift. Usually, a 60R resistor is cost effective and a choice of 60.4R with 1% tolerance is better.
If CAN-BUS communication is chosen for long distances of more than 50m, it is advised to reduce the bitrate to minimize errors and signal distortions.
The maximum possible CAN Bitrate depends on the total CAN bus cable length:
- 1 Mbit/s: max. 40 m
- 500 kBit/s: max. 100 m
- 125 kBit/s: max. 500 m
A varistor should be added near the connectors to enhance CAN Bus reliability.
If the device is intended to be used in a harsh environment and requires isolation due to ground potential differences between subsystems, a Galvanic isolation barrier can be placed between the CAN-BUS transceiver and the MCU. Using an isolated DC-DC power supply for the transceiver is important.
