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TCAN1146-Q1: bus fault detection principle

Dongbao Zhou
Expert 4170 points
Part Number: TCAN1146-Q1

hi team,

May you share more details on the bus fault detection principle?

For example the detection threshold (voltage/current), as well as the deglitch time.

Beside, normal can bus network usually have serval 2.2kohm termination resistor, any impact to the detection accuracy?

Regards,

Dongbao

  • +1
    TI__Guru 53575 points

    Hi Dongbao,

    The TCAN1145 uses an internal current measurement of the CANH and CANL pins during a dominant state to determine if there is a bus fault present on the bus. For instance if the current through either pin is greater than what is expected over a 60-ohm nominal load, the device can recognize a short between the bus pins. The current measurements can also be compared to one another to determine if there is an asymmetric short such as CANH short to ground. In this case the CANH current would be smaller than the CANL current. 

    We do not specify the exact thresholds at which the error will be recognized as the way that the circuit is a bit more complicated than it may initially seem. The circuit is designed to catch any bus condition that is far enough outside nominal conditions to significantly impact CAN communication. Partial termination such as 2.2k-ohm on intermediate nodes will not be enough to trigger the CANH short to CANL condition as this would not significantly impact the CAN signal in a negative way. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott