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Original question:

TCAN1051HGV-Q1: Request for IBIS model

TCAN1051HGV-Q1: Issue with IBIS Simulation

Pierre Amblard
Prodigy 40 points
Part Number: TCAN1051HGV-Q1
Other Parts Discussed in Thread: TCAN1044-Q1

Tool/software:

Hi,

I used the IBIS model of the TCAN1044-Q1 (which is identical to the TCAN1051HGV-1) for signal integrity (SI) simulation. When performing the simulation using the differential pins (6-7), I encounter an error message related to the IBIS model.

As an alternative, I tested the single-ended mode, and I was able to establish communication between the two CAN devices without any issues. However, during the simulation, I observed the correct inverting signal, but with different voltage levels. Specifically, in "Recessive" mode, where CANH is LOW and CANL is HIGH, the voltage is 2.3V instead of the expected 2.5V as specified in the datasheet. Is this normal?

Best Regards, 

Pierre

  • 0
    TI__Guru 52435 points

    Hi Pierre,

    I don't believe this model is set up for a differential implementation, so the singe-ended approach is likely best here. This is how I use our models as well. 

    The polarity of this signals is correct. CAN defines the dominant state (logic level 0) with a positive differential between CANH and CANL. In this state the transceiver will drive CAN towards the pull-up reference (5V) and CANL will pull-down towards ground. Thus the differential CANH - CANL will be positive (1.5V minimum required by the CAN standard). The recessive state (logic level 1) has a near 0 differential (50mV max by standard) between CANH and CANL so both signals will tend towards the common mode of 2.5V. Simply if you look at the signals individually, CANH will be the inversion of the TXD, RXD, and CANL signals which should all match.  

    In this case it looks like the model does tend to lower this common mode to hover closer to 2.3V than the typical 2.5V. I'm not quite sure the reason for this, but because this does not impact the differential signal it will have no impact on the communication in your test. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott