2 What are the Options Available to Isolate CAN Bus?

Isolation of CAN bus is accomplished by placing an isolation barrier at digital logic interface between the MCU and CAN transceiver. System designers use either discrete or integrated solutions for isolating CAN bus. Discrete solution can be implemented using a digital Isolator such as ISO7721, and a CAN transceiver. The CAN standard places strict timing requirements on total loop delay and on pulse width distortion for FD data rates (2 Mbps and 5 Mbps). Discrete solutions will need to account for PCB parasitics that exist in the signal path which can impact timing, to ensure they are compliant to the CAN standard since timing is critical for bit-wise arbitration and signal integrity. Integrated isolated CAN devices such as ISO1042, ISO1044, and ISOW1044, other than providing board space savings, have these timing specifications guaranteed in the data sheet, eliminating extra simulations and tests needed for discrete solutions. Figure 2-1 shows this concept using ISO1044.

Figure 2-1 Integrated Ultra-Small Package Isolated CAN Device ISO1044