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TCAN1043A-Q1: RXD Max Drive Capacitance Value

David Shumate
Expert 7895 points
Part Number: TCAN1043A-Q1

Hi Team,

For TCAN1043A I see that the RXD is tested with 15pF of capacitance:

This is for a typical usecase, can you help clarify what the max acceptable CL_RXD in application would be?

Thanks,

David

  • 0
    TI__Guru 53555 points

    Hi David,

    This capacitance is included in the test case to model any trace capacitance on the signal line. It is not too common to include such capacitors in an actual application (series resistors are fairly common though). In designs that have particularly long trace lengths or high board capacitances, the system designer may need to factor in how this will impact the digital CAN signal. As CAN is relatively slow for a digital signal, this is rarely the first place this consideration will be necessary in a design. 

    Let me know if you have any more questions.

    Regards,
    Eric Schott 

  • 0 in reply to Eric Schott1
    TI__Expert 7895 points

    Hey Eric,

    Sorry, the question is actually about board capacitance not adding a discrete cap. The customer is trying to understand what the max allowable board capacitance is that can be driven by the RX.

    Thanks,

    David

  • 0 in reply to David Shumate
    TI__Guru 53555 points

    Hi David, 

    There is not a hard limit on board capacitance as this will depend on the data rate used in the system. Does the current design plan to have significantly more than 15pF of trace capacitance? What is the desired data rate for this design?

    Note that in most cases where there is no cable involved, trace capacitance is not the limiting factor in CAN data rate.

    Regards, 
    Eric Schott