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Original question:

SN65HVD23x 3.3-V CAN Bus Transceiver

SN65HVD230: IC failure

MounishPatel Seetha
Intellectual 690 points
Part Number: SN65HVD230
Other Parts Discussed in Thread: ESD2CAN24-Q1

Hi, I am using SN65HVD230 as CAN transceiver, I would like to know what is the recommended bus capacitance or TVS diode capacitance ?, So that bus operation and its life is optimal

Thanks & Regards

Mounish

  • 0
    TI__Guru 72272 points

    Mounish,

    It's fairly dependent on the amount of other CAN transceivers on the CAN bus, but in general the added capacitance ranges from 10pF to 100pF on each CAN bus signal (CANH and CANL). CAN transceivers themselves typically have 20pF to 40pF from CANH/CANL to GND, this parameter is listed in the datasheet. But again, it's heavily dependent on the amount of CAN nodes on the bus. More nodes means you have less margin for added filter capacitance, and vice versa.

    For TVS diodes, any CAN specific diode will have minimal capacitance to help with overall bus capacitance, so I'd recommend looking at the ESD2CAN24-Q1 device from TI. 

    Please let us know if you have any other questions.

    Regards,

    Eric Hackett

  • 0 in reply to Eric Hackett
    Intellectual 690 points

    Erick Hackett,

    1. ESD2CAN24-Q1 this diode has a clamping voltage of 43V but absolute max value is only 25V right? is this ok? Can SN65HVD230 withstand this ?

    2. Also Can I these diodes in parallel to increase current handling capability during surge as in IEC 61000-4-5?

    Thanks & Regards,

    Mounish

  • 0 in reply to MounishPatel Seetha
    TI__Guru 72272 points

    Mounish,

    1. You are correct, I misspoke about the absolute maximum rating of the 3.3V CAN transceiver family. Disregard the recommendation.

    2. Theoretically you can, but this is not something I've seen done in practice.

    Do you have any more questions or information about the failure you're experiencing?

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    Intellectual 690 points

    Eric Hackett,

     Now when the charger is connected to the Battery( BMS ), Only Some times my CAN transceiver fail. I suspect that transients emitted from the charger are getting magnetically coupled into the CAN bus, which is giving a high voltage surge in the CAN bus. Am I Correct?

    Note: Power wires and CAN bus wires are in the same cable parallel and close to each other.

  • 0 in reply to MounishPatel Seetha
    TI__Mastermind 26756 points

    Hi Mounish,

    The US is on holiday for the remainder of the week. It is possible that responses will be delayed until Monday.

    Best,

    Danny

  • 0 in reply to MounishPatel Seetha
    TI__Guru 72272 points

    Mounish,

    This is likely what is happening. Magnetic coupling and even accidental shorts have a much higher chance of occurring when the power cable is bunched with the communication cables. If these transients are going to high enough levels, they can cause overvoltage stress on the pins and cause damage.

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    Intellectual 690 points

    Eric Hackett,

    Just one more question, what if the bus capacitance is some where like 5200pF, will this cause only signal distortion or IC failure?

    Note:

    1.I checked that IC is not heating and since there are only two devices there is no communication interruption

    2. I checked CANH,CANL signal with oscilloscope there is slight distortion at the edges

    Thanks&Regards

    Mounish

  • +1 in reply to MounishPatel Seetha
    TI__Guru 72272 points

    Mounish,

    I would not expect damage to occur with too much capacitance on the bus, but signal distortion will definitely occur, especially at high data rates. The edge slowing could cause the bit to be delayed significantly or be missed entirely.

    Regards,

    Eric Hackett