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Help me - CAN bus isolation

Laurian Antoci
Prodigy 70 points
Other Parts Discussed in Thread: ISO1050

I design some control devices that connect to each other on the  CAN bus and I have a problem with the CAN bus isolation. I can  choose from three possibilities to place CAN transceiver but do not know which one to choose and don't have communication or other problems but also be cheap. I think the first option would  be best but more expensive. I would be interested to give me some  advice if its worth using one of the following 2 or 3 and which one. If you can please tell me and what problems can occur in each case. I attached all the three schemes with possibilities that i have.
Details:
-  Each device are powered from 12V lead batteries and don't have common ground.
- CAN bus line will be up to 1000m and it will connect up to 100  such systems. CAN speed: 50Kbit/s. I wanted to use SN65HVD251D. U have a better suggestion?

Thanks

Laurian Antoci

  • 0
    TI__Mastermind 28265 points

    Schema 1 looks good. You can use ISO1050, which is a CAN transceiver with integrtade signal isolation to save many opto couplers.

    best regards,

    thomas

  • 0 in reply to Thomas Kugelstadt
    Prodigy 70 points

    I know scheme 1 is the best, but the price is significantly higher because there are two  isolated DC/DC converters I prefer to choose the best one between scheme 2 and 3 .  If I go for scheme 2, will I have problems / interferences in  CAN communication? If i choose scheme 3 will I have malfunction in digital module because of the non isolated CAN bus?

    Many thanks

    Laurian

  • 0 in reply to Laurian Antoci
    TI__Mastermind 28265 points

    WE ARFAMILR WITH SCHEME 2 AND 3. THE BEST WAY TO FIND OUT IS PROTOTYPING. THERE IS NO GUESSING POSSIBLE.

    REGARDS, tHOMAS

  • 0 in reply to Thomas Kugelstadt
    TI__Mastermind 28265 points

    What I wanted to say is we are NOT familar with these concepts. They are actually not clear. In the 3rd scheme you are not isolating any CAN bus.

    what is your goal? what nedds to be isolatoed from what?

    You stated that you knew that scheme 1 was the best but did not like the cost of the isolated power supplies. My advise, particluarly for the isolation business, don't trade quality for cost. If you risk a product recall from the field, these cost will outweigh your investment into proer power supply isolation.

    so before we can be of further help, we need to know what needs to be isolated from what.

    Regards,

    Thomas