TCAN4551-Q1: Usage scenario

Hi Daniel,

Daniel Wang (auto) said:

1. For TCAN4551 and TCAN4550, are they used in a domain controller or ZCU? Or an independent sensor or actuator CAN module?

The TCAN455x devices can be used in any CAN or CAN FD application and in any type of CAN module.

Daniel Wang (auto) said:

2. Is there a usage history in gateway functions? What is the approximate bus load, or what is the recommended maximum bus load?

All communication, including CAN TX and RX Message data must pass through the SPI bus interface, so the maximum bus load will vary with the efficiency of the SPI interface and the MCU.  There are too many variables and unknowns for me to be able to provide you any specific value for what is the maximum bus load.  You will need to determine this for your application by measuring the overall time it takes to transmit and receive a CAN message which includes your interrupt detection, reading the RX/TX FIFO status registers, transferring the CAN message data into and out of the MRAM buffer elements, and then the register writes to initiate a message transmission or to acknowledge a RX message has been read.

Trying to receive CAN messages faster than the MCU can process them through SPI will result in data loss if the RX FIFO or buffer elements become full.

Daniel Wang (auto) said:

3. What is the maximum baud rate used for the data segment?

The maximum high-speed clock (crystal oscillator) frequency that is supported is 40MHz.  This allows a 5Mbps or 8Mbps max CAN FD Data bit rate simply based on the number of time quanta or clock cycles used to make up the CAN bit timing parameters.  But note that often real wiring harnesses and CAN buses with multiple nodes and environmental conditions may not be clean enough to support the maximum bit rate due to signal reflections and non-linear wiring topologies and again this will need to be determined for your application.

Daniel Wang (auto) said:

4. What is the RTM date? 

The TCAN455x devices were RTM in December 2018.

Please review the TCAN45xx Software User's Guide (Link) for more information on SPI optimization and CAN bit timing configuration.

Please also review the TCAN455x Clock Optimization and Design Guidelines Application Report (Link) for more information on how to implement and optimize the clock interface for their design and ensure stable operation.

Regards,

Jonathan