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SN65HVD234: CAN waveform pass and fail criteria

Di Hu
Prodigy 40 points
Part Number: SN65HVD234

Tool/software:

Here is the differential waveform that we measured near the CAN transceiver. This is measured using a differential probe probing CAN_H and CAN_L. We see the glitch on the falling edge and ringing on the rising edge. Is this acceptable? Can you please provide us with the pass/fail criterial for the waveform

  • +1
    TI__Genius 13472 points

    Hi Di Hu,

    Thanks for posting on E2E!

    Depending on the data rate, number of devices on the bus, amongst other factors, the short answer is yes, this waveform seems passable.

    As you already highlighted, since CANH and CANL are differential all that matters is the voltage difference between them. Based on the CAN standard, a dominant state is > 0.9V differential and a recessive state is < 0.5V differential. So depending on where the sampling point is in your waveform, this appears to be passing. I have seen much noisier waveforms that still communicate with valid voltage levels. 

    I would recommend measuring CANH and CANL, but also measuring RX to see how it responds. You are more than welcome to share a schematic, and I can review that to check for anything concerning or look for improvements if that would be helpful. 

    Let me know if that helps or if you have further questions,

    -Ethan