TCAN1462V-Q1: Transceiver Delay Mechanism

Ray,

The maximum CANFD speed is 5 Mbps. A single bit at that rate would be 200 ns. So it is not less than the loop delay unless they are operating at speeds greater than the maximum CAN FD speed. Our devices can operate at 8Mbps but this is under specific loading conditions and small bus lengths. You would also need to find a CAN controller that can support speeds faster than 5 Mbps.

You can read more about loop delays in this document. Now during a CANFD message there are two parts of the message. The arbitration phase and then the data phase. During arbitration multiple CAN devices can communicate at the same time. So it is important that every device can read the bits on the CAN bus at the same time so that they know if they are losing arbitration or if the message is meant for them. That is why for arbitration the maximum speed is limited to 1 Mbps. However, depending on your CAN bus loading you might have to use a lower speed so that each device can compensate for the propagation delay. The document I linked about talks about this in detail.

Now when you enter the data phase, it is one device transmitting on the bus so the propagation delay does not matter any more. The device transmitting does not care if the other devices are receiving the bits much later than when it sends it.

Best,

Chris