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SN65HVD251 Thermal Issue

Jigar Patel93027
Intellectual 750 points
Other Parts Discussed in Thread: SN65HVD251

Hello,

I am using Following circuit for CAN Interface between two boards. CAN interface works fine at all the points. But recently found a new issue. As soon as  enclosure temperature (Specially SN65XXXXX) rises more than 55 C, CAN transceiver  goes to some Thermal Shut down mode. It does not Receive or transmit anything. Based on datasheet Thermal shut down happens only after 165C. Do not know if I can Disable this? or something wrong with the circuit.

Please advise ASAP. I am stuck with this issue long time.

Thanks

Jigar

  • 0
    TI__Guru** 103215 points

    Hello Jigar,

    I don't see any obvious issues with the circuit but I did notice that the operating temp of SW16 is only up to 85C. Perhaps the termination resistor R10 is getting switched out of the circuit when the switch gets hot? Have you tried testing the performance of the circuit with the termination hard tied to the bus? 

    How did you conclude that the SN65HVD251 was entering thermal shutdown mode? Does the device switch off entirely or cycle back and forth between off and on? Also just to clarify it is not possible to disable the thermal shutdown mode as this is designed to protect the die from damage however I think it's unlikely that thermal shutdown mode is getting triggered at just 55C. There may be some other issue. 

    Best Regards,

    Casey McCrea

  • 0 in reply to Casey McCrea
    Intellectual 750 points
    Thanks Casey,
    I will check SW16. But I normally leave it open as my second board has 120 ohm Terminator. I will still verify.

    Yes, CAN transceiver turns OFF and ON between > 55 and < 45.
    By reading Datasheet I know, it should not triggered Thermal Shutdown. But it gets affected only by Temperature. Otherwise it works fine days and Night.

    Please advise if you find anything else.

    Thanks
    Jigar