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TCAN1044A-Q1: system design

Hale Tan
Expert 3770 points
Part Number: TCAN1044A-Q1

Hi team,

As the regular CAN system design, there will always be a single 120-Ω resistor at each end of the bus. And the customer want to make sure one thing: if the end TCAN1044 has been broken or removed, is there any other influence on the other TCAN1044 in the same CAN system design due to lack of the 120 ohm resistor?

  • 0
    TI__Guru 53555 points

    Hi Hale,

    In the case where a CAN bus is underterminated with only 120-ohms between CANH and CANL, the dominant-to-recessive transition of the differential signal will be slowed. This can have the effect of lowing the effective data rate that the system can operate at. If the system was already operating near the maximum data rate that it can support, this increased fall-time will like lead to communication errors. In this case the system may attempt to lower its data rate by only sending classic CAN frames and reverting to a failsafe bit rate so that the fault may be properly diagnosed. If the system has some buffer in capable supported data rate rate, it is possible that communication will be uninterrupted due to the relatively mild nature of the underterminated bus fault. 

    Let me know if this is clear and if you have any more questions. 

    Regards, 
    Eric Schott