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SN65HVD1781: Bus-Pin Fault Protection - Testing

Amarnath Murugadass
Intellectual 480 points
Part Number: SN65HVD1781

Hi Sir/Madam,

We are currently using SN65HVD1781 in our design. We would like to test the Bus Fault protection up to 60V of the part. What is the timing of the 60V voltage level we can provide to IC without damaging the component. Is there any other protection we need to follow to avoid damage to the board? What is the current limit we need to set for 60V power supply?

If any test setup is available please share it so the same can be followed to protect the IC or board from damage.

 

Regards,

M Amarnath

  • 0
    TI__Guru 53575 points

    Hi Amarnath,

    The SN65HVD1781 device can withstand up to ±70V on its bus pins for extended periods without experiencing damage. For an applied 60V test, no special timing parameters or current limits need to be considered. 

    Please ensure that the test voltage is applied gradually as transient connections (such as connecting a charged cable directly) can induce voltages that exceed the desired test level. Connecting cabling before the voltage is applied is preferable as the supply source generally ramps to the set voltage relatively slowly due to supply capacitance. Also note that if any external protection devices such as TVS diodes are present, they may reach thermal limits if they are kept clamps for extended periods. 
    Lastly note that the datasheet states "Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability". While damage should not occur after a reasonable amount of time at absolute maximum conditions, reliability factors such as lifetime may be reduced. 

    Let me know if you have any more questions.

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    Intellectual 480 points

    Hi Eric,

    Thank you for your support.

    We are planning to test both the RS485 signal lines with +/-60V voltage levels with respect to GND for 10ms. Hope it will not cause any damage to the device.

    Also if you can share any App note or Test setup images we can refer it will be helpful.

    Thanks & Regards,

    Amarnath

  • 0 in reply to Amarnath Murugadass
    TI__Guru 53575 points

    Hi Amarnath,

    This device should be able to withstand a ±60V bus fault without damage for much longer than 10ms. 

    I'm not aware of any content we have demonstrating a simple DC short test, but you may be interested in this document describing some ESD test setups for RS-485. 

    Regards,
    Eric Schott