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DS92LX2121 / DS92LX2122 Hot Swapping

Bradley Helsel
Intellectual 260 points
Other Parts Discussed in Thread: DS92LX2121, DS92LX2122

Hello Forum,

I am using a DS92LX2121 / DS92LX2122 chip set for a remote touch screen display. The Serializer and Deserializer are in separate housings and connected using a Cat5E cable. At the Serializer end of the cable there is an M12 connector for connecting the remote display to a control box. I have experienced IC destruction when disconnecting the display from the controller via the M12 connector while the system is power up. I have followed the design guidelines for this chip set in both the schematic and layout. In all cases of IC destruction, the LOCK bit is no longer at a steady state.

What other design approaches can I take to mitigate IC destruction when disconnecting the SERDES link while power up?

  • 0
    TI__Expert 7395 points

    Hi Bradley,

    How did you determine the IC was damaged? There should be 100nF ac decoupling caps between the connector and serdes device. Can you check if the cap is damaged (ie shorted or open)? If it turns out to be an electrical overstress caused hotplugging, then you may need to implement some protection circuitry.

    Dac Tran

    SVA APPS

  • 0 in reply to Dac Tran
    Intellectual 260 points

    Hi Dac,

    I have not yet fully proven that it is the IC that was damaged. I be working on this issue in the coming weeks since it is now becoming a requirement for the remote display to withstand a hot swap.

    Do you have any reference designs for protection circuitry that could be used on the SERDES link?

    Regards,

    Bradley Helsel