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SN65HVD251: IC getting short VCC to GND

Narayan P Sangale
Prodigy 110 points
Part Number: SN65HVD251
Other Parts Discussed in Thread: STRIKE

Dears,

We are using  IC SN65HVD251D in our designs.

We are facing issue of IC getting short VCC to GND (VCC and GND pins are observed shorted together).

We are observing this problem repeatedly.

IC SN65HVD251D is operating on 5VDC.

Also IC output is protected from tvs diode.

Please note that the we have cable length of about 30 meter long which carries 24VDC and from this 24VDC we have generated 5 VDC using DC to DC converter LM2672M_ADJ.

This power supply is also protected with transorb, ferrite bead in series with output and input and output capacitor filters.

 

Can you please help us to identify;

Possible causes of IC damage?

What are the parameters which can damages the IC?

Preventive measure and circuit protection guidelines?

Types of Measurements in filed to find out the root causes?

Design support for robustness improvement to avoid failure?

 Please see attachment for the IC damage images

  • 0
    TI__Guru 69612 points

    Narayan,

    Thank for the information, and sorry to hear that the SN65HVD251 is having failures. The protection you have in place sounds sufficient to protect against a voltage transient or ESD strike on the bus, as well as on the power input. Typically when this kind of damage occurs, it is due to electrical overstress such as an ESD event or longer transient voltage pulse on the CAN bus. However, in this case it could also be the absolute maximum rating being surpassed on the VCC pin.

    I have a few questions:

    • Can a schematic be shared? If not on E2E then directly to my email would work, you can click on my username to find it. If the schematic cannot be shared at all, can you let me know if there is a common-mode choke populated on the board?
    • Is it possible to monitor the DCDC converter output/transceiver VCC input? It'd be good to know if there was ever a spike on the voltage converter output that would feed into the VCC pin of the transceiver. 
    • Can the CANH and CANL pins be captured before and after the damage occurs?
    • Does this damage occur to every unit? Or how often does this damage happen?

    Getting this information will help narrow down what is happening.

    Regards,

  • 0 in reply to Eric Hackett
    TI__Guru 69612 points

    Narayan,

    Do you have any updates on this? Are there still issues with devices failing?

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 110 points

    Hi Eric,

    Yes problem is still there.

    I was checking with idea of sharing the schematic with you.

    I will revert back to you once i get the permission.

    Still you can share your inputs.

    Regards,

    Narayan Sangale

  • 0 in reply to Narayan P Sangale
    TI__Guru 69612 points

    Narayan,

    Were you able to get any other information from my original questions? I see you're working on the schematic.

    In general for CAN applications, you'll want to follow a generic protection guideline like this:

    Where CH1 and CL1 help with high frequency noise and slowing down edges of high-voltage transients. CH2 and CL2 serve the same function. The common-mode choke will also help with high-frequency noise. Adding series resistors to CANH and CANL can also help, but this will also limit this amount of nodes that can be placed on the CAN bus.

    From your original post, the customer seems to be taking all these precautions, so some more information will help figure out where else this damage could be coming from.

    Regards,