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TCAN1051HG-Q1: Designing with TCAN1051HG-Q1

Sv
Intellectual 555 points
Part Number: TCAN1051HG-Q1
Other Parts Discussed in Thread: ISO1044, ISO1050, ISO1042-Q1

Tool/software:

Hello Team,
We have a system with can interface and the transceiver using is TCAN1051HGVDR.

The CAN signals are taken through twisted pair cables only but they had to travel through a breakout box, wiring harness before reaching the 2nd CAN device.
We have termination resistors of 120 ohms on both CAN sides.
The resistance between the CAN H lines between either end is almost 5 ohms similarly for CANL lines (Measured with a multi meter, the breakout box, and harness add the line resistance.)

1). Will this resistance create any problem?.

2). Do we need a GND lines along with CANL and CANH lines between the CAN devices as they are working with 2 different power supplies and the GND is not connected together?.

3). We have a junction box connected at the breakout box side and 2 CAN analyzer devices are connected at the junction box.
Since each are CAN nodes, which is the ideal place yo connect the termination resistor?.

4). Sometimes we have to add an extra 120 Ohms resistance at the analyzer side for proper communication (the effective resistance will be 40 Ohms). Why is this?.

Looking for your reply

  • +1
    Guru 316860 points

    1. No.

    2. The TCAN1051HG-Q1 can tolerate ground shifts of up to ±25 V. You do not need a GND line if you can ensure in some other way that the offset is lower than that.

    3. The bus must have exactly two termination resistors, at the two ends of the bus. The analyzers must not have resistors (and their connection to the bus should be as short as possible).

    4. I'd guess that the length of the spur is too high. Try using AC termination, but this limits the speed.

  • +1 in reply to Clemens Ladisch
    Intellectual 555 points

    Hello Clemens,
    Thank you for your quick reply.

    1). So is there any limitation for the line resistance for CAN lines.

    2). Can you please explain what is spur and AC termination. Did you mean Split termination?.

    3). Can you please suggest any footprint compatible isolated CAN transceiver for the IC TCAN1051HGVDR.
    We can use wires to connect the isolated side power since we don't have an isolated power in our board.

    4).

  • +1 in reply to Sv
    TI__Guru 51006 points

    Hi SV,

    1. No, as long as the termination resistors are well valued for a matched output impedance.
    2. Yes, RC filter as a form of termination.
    3. ISO1042-Q1 is the main Q1 alternative in our portfolio. However, ISO1050 and ISO1044 show similar footprints. Please let us know if additional isolated CAN recommendations are needed and we can forward to the ISO team if any additional alternatives, thanks.

    Best regards,
    Michael.