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SN65HVD1050: SN65HVD1050 CAN_H Short

Lina Wang
Intellectual 960 points
Part Number: SN65HVD1050
Other Parts Discussed in Thread: STRIKE, TCAN1051

dear Sir,

my customer used SN65HVD1050, it is failed return back from end customer, we find fin7 (CAN_H) short to the Ground.

there are happened three times for this issue.

below is their schematic, pls check it.

and could you help to suggest what's reason will result in CAN_H short to Ground, and what's the method to avoid this issue.

  • 0
    TI__Guru 62920 points
    Hi Lina,

    This is the most common failure mechanism of electrical overstress. This could occur as a result of a transient event such as an ESD strike, although I see there is a TVS diode for protection in this application. Another likely cause would be a short circuit on the CANH line. Although the device is protected against DC shorts within the absolute maximum voltage ratings, when a common mode choke is used it can induce large transients at the transceiver pins if the shorted node remains active. (An active node would drive large currents into the short when dominant and very low currents when recessive, and the large and rapid change on current can interact with the inductance of the choke to generate large voltages).

    If this second reason is the cause of the damage, switching to SN65HVDA1050A or TCAN1051 may be the simplest solution.

    Max
  • 0 in reply to Miguel Robertson
    Intellectual 960 points

    Dear Robertson,

    do you have some method how to distinguish root cause is your first reason or the second issue?

     

  • 0 in reply to Lina Wang
    TI__Guru 62920 points
    Unfortunately both causes would result in similar damage to the device. However, since ESDCAN01-BLY is placed on the connector side I would expect it to be effective in protecting the transceiver against any transients that couple onto the PCB from the external environment. Transients generated by the choke during a short-circuit seems like a much more likely root cause to me (unless you know that this application has no risk of short-circuits to power or ground lines). You can read more about this phenomenon here: www.ti.com/.../slla271.pdf.

    In addition to changing to a more robust transceiver device, another effective solution could be to place the TVS diode on the other side of the common-mode choke. This way, it would clamp not only the externally-coupled transients but also the ones generated on the PCB by the common mode choke inductance.

    Regards,
    Max