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SN74CB3Q3251: Using with CAN signals

Elisha Tarroza71
Expert 3700 points
Part Number: SN74CB3Q3251

Hello, 

Can this device be used for CAN signals? Customer is saying the signals, both at the input and output, gets distorted whenever the chip is enabled.

However, when the device is still disabled, the input signal is OK. 

Can you please advise?

Thank you for your help.

  • 0
    TI__Expert 5660 points

    Hello,

    SN74CB3Q3251 supports rail-to-rail (recommended 0V to 5.5V) switching at data I/O ports.

    What is the value of VCC for the system?

    To help me understand, could you please send the expected waveform (when device is off) and the distorted waveforms at the input and output (when device is on)?

    Thank you!

    Regards,

    Kate

  • 0 in reply to Kate Dickson
    Prodigy 125 points

    Hi,

    Thank you for the reply.

    The VCC is 3.3V. 

    I have attached the schematics and the proper and distorted signal captures to this ticket. Can you please check this ticket? CS0088320. I do not want to put the schematics into public domain for now.

    The schematics will clarify most of the question that you might get. However, please let me know if I can give some more details.

    Thanks and Best Regards,

    Shrikant

  • 0 in reply to Shrikant Sagar
    TI__Expert 5660 points

    Hi Shrikant,

    Thank you for sending that information. Just to clarify, are you seeing this behavior at both of the MUXes? 

    Also to clarify, you see this distorted waveform when /OE pin is "low"?

    Regards,

    Kate

  • 0 in reply to Kate Dickson
    Prodigy 125 points

    Hello  Kate,

    Yes that's true. I am seeing the same behavior for both muxes. If you see the OE pin it's common for both Muxes and so if I disable or enable it applies for both Muxes. And yes to your question regarding the value of /OE pin. Enable I mean 0 to /OE and disable I mean 1 to /OE.

    Thanks and best regards,

    Shrikant

  • 0 in reply to Shrikant Sagar
    TI__Expert 5660 points

    Hi Shrikant,

    Thanks for the clarification. Our team is looking into the information you sent us and I will get back to you next week.

    Best regards,

    Kate

  • 0 in reply to Kate Dickson
    Prodigy 125 points

    Hi Kate,

    Just to know the status. Is there something for me ? :)

    Thanks and Best Regards,

    Shrikant

  • 0 in reply to Shrikant Sagar
    TI__Expert 5660 points

    Hi Shrikant,

    Thank you for your patience.

    Are the scope shots you sent of the waveforms at the input (pin A)?

    Could you send a shot of the input (pin A) and the output (pin Bx) in the same shot when the switch is enabled? Please let me know which output pin you are using.

    Additionally, could you send a scope shot of the signals on the select pins (/OE, S0, S1, S2) when the switch enabled? I want to confirm that the expected output pin is in fact selected.

    Another test you can try is removing the mux by shorting the input to an output line (RXD to RX1, for example) and measuring to see what the waveform looks like at that node.

    What is the End Equipment for this application? I would like to suggest using TI's pin to pin device recommendation for MCP2562, which is TCAN1042V.

    Best regards,

    Kate

  • 0 in reply to Kate Dickson
    TI__Expert 5660 points

    Hi Shrikant,

    I'm just checking in to see if you had any updates.

    I will close the thread for now, but please feel free to re-open it with a reply.

    Best regards,

    Kate