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TCAN334G: CAN bus related issues

jeno.zhang
Genius 3035 points
Part Number: TCAN334G
Other Parts Discussed in Thread: TCAN1462-Q1

Tool/software:

Hello,

CAN communication requirements:
1. The length of single packet communication data on the CAN bus reaches 64 bytes.
2. The CAN communication rate is 20kbps (adjustable depending on the number of nodes).
3. The maximum number of nodes on the bus can reach 400, but at least 200 are required.
4. CAN transceiver explicit timeout, single transceiver failure cannot disrupt bus communication.


The customer has the following questions:
1. Is CAN FD suitable for our usage scenario?
2. Are there any possible hidden dangers? For example, signal interference?
3. The necessity of CAN SIC?
4. Based on the working voltage, power consumption, and other parameters of the integrated chip, it is believed that TCAN334GDR is the most suitable for the requirements.
5. Is TCAN334GDR compatible with the functionality of TCAN334DR, meaning that the current standard CAN can use TCAN334GDR instead of TCAN334DR?
6. What is the difference in operating current parameters between TCAN334GDR and TCAN334DR, especially in the receiving mode?
7. Do you have any other design suggestions?

Thanks！

  • 0
    TI__Guru 58057 points

    Hi Jeno,

    1. Yes, CAN FD supports up to 64 bytes.

    2. 200-400 nodes can be excessive. Capacitive loads adds up as each node adds bus capacitance. Reflections are common. For example the data sheet's RID is 30 k ohms. For 100 nodes implying 100 devices in parallel, the equivalent bus load will be 300 ohms. This total bus load in parallel with the nominal 60 ohms CAN bus termination implies 50 ohms. This is close to the expected 60 ohms. Hence, still acceptable. With 200-400 nodes, the bus will be heavily loaded (with reflections) observing about 43 to 33 ohms. Below 45 ohms, the device will most likely struggle to meet the data sheet's minimum differential voltage (VOD) of 1.5 V and would recommend CAN SIC devices such as TCAN1462-Q1 to perform better for 200 nodes compared to non-SIC devices.

    3. Yes, see 2. SIC is recommended for larger node counts and harsh environments

    4. No, for such an environment, SIC is the most suitable. VIO can also support 3.3 V.

    5. Yes.

    6. The data sheet do not specify any difference. The device is the same just different packages.

    7. Yes, any CAN SIC devices, thanks.

    Best Regards,

    Michael.