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Ryker She
Expert 4310 points
Part Number: TCAN1145-Q1

Tool/software:

Hi expert,

Do we have some standard or some document of CAN terminal resistor? When the resistor is less than a certain value, the system can't work? Thanks,

Best Regards,

Ryker

  • 0
    TI__Guru 53555 points

    Hi Ryker,

    We do not have any dedicated material discussing the impacts of too large of a resistive load (too small of a resistance value between CANH and CANL). The CAN standard allows for optional specification of performance across an extended bus load from 45-ohms to 70-ohms and many of our devices include this information - so the impact of a load value down to 45-ohms can be fairly well understood. Loads greater than this will continue to decrease the output differential on the CAN bus and make the system more susceptible to differential noise or voltage drop across cable impedance. I would typically recommend against defining a system with less than 50-ohms of resistance between CANH and CANL so that some margin can be maintained for variance.

    Do you have more information on reason for interest in this topic? We may be able to address the root concern if a system designer is considering multiple termination locations or adding some other form of differential loading to the bus. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott