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TCAN4550: one question about TCAN4550

Oliver Ou
Intellectual 2845 points

Part Number: TCAN4550

Hi,

our customer has questions about our SPI to CAN solutins: TCAN4550/1.

What are the differences for this two parts ? How long trace can these solutons support?  Over how long trace do we need to add CAN transceiver? 

Thanks.

  • 0
    TI__Mastermind 36701 points

    Hello Oliver,

    Here is a comparison table of the differentiated features between the two devices.

    Generally speaking, the TCAN4551 is a reduced feature version of the TCAN4550.  The watchdog and 5V LDO output have been removed from the device and the GPIO "Input" features have been removed and only the "Output" configuration for those pins are available on the TCAN4551.  The last main difference between the two devices is the VIO range for the TCAN4550 is 3.3V to 5V and support for 1.8V MCU's has been added for the TCAN4551 allowing for a 1.8V VIO to be used.

    I'm not sure  what trace length you are asking about?  Are you asking about the trace length between the MCU and the TCAN455x on the SPI bus?  If so we don't have a specification for this and it is related to the signal amplitude between the MCU and TCAN455x device.  As long as the signal amplitude crosses the 0.7*VIO High threshold, and the 0.3*VIO Low threshold, the communication should work.  These thresholds may differ between the MCU and the TCAN455x devices so both device specifications must be met.

    The CAN transceiver is built into the TCAN455x device and there is no need to add a CAN transceiver.  This is the main feature of this device.  Simply connect the TCAN455x to the MCU with a SPI bus, and the TCAN455x pins to the CAN bus.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Intellectual 2845 points

    Hi Jonathan,

    Cusotmer wants to know the maximum trace length from TCAN455x pins to the CAN port.

    Thanks.

    Oliver Ou

  • 0 in reply to Oliver Ou
    TI__Mastermind 36701 points

    Hi Oliver,

    There it is no maximum trace length specification between the TCAN455x pins and the PCB connector which is what I am assuming you mean by "CAN port". 

    The CANH and CANL pins of the TCAN455x are electrically connected to the CAN bus and therefore they are fully capable of driving a fully loaded bus including the wiring harness which is typically specified as up to 255 nodes along a 40 meter cable.  This maximum bus length is also dependent on several factors such as data rate, number of nodes, type of cable, and the topology of the but itself (such as whether it is linear or a star network with long stubs and branches, etc.) 

    Since the TCAN455x is capable of driving such a large load, the amount of trace length between the PCB connector and the TCAN455x pins is generally considered negligible.  in context to the entire bus.  As a result there are no real specifications for a maximum trace length.

    Regards,

    Jonathan