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SN65LVDS125A: Use of LVDS Crosspoint switch in LVDS Fault Testing Setup

Benjamin Uhing
Intellectual 2025 points
Part Number: SN65LVDS125A

I have a system with two ASICs communicating one-way (simplex) using 400 MHz LVDs signalling. I need to test what happens to the receiver ASIC when the LVDS signals are interrupted (the three test cases are disconnected, shorted to ground, and shorted to VCC). Could I use a SN65LVDS125A (or similar Crosspoint switch) in my test setup?

My thought is to have the LVDS data from the transmitting ASIC connected to 1A and 1B, ground 2A and 2B, tie 3A and 3C to VCC, and leave 4A and 4B floating. I would have 1Y and 1Z connected to my receiving ASIC. Then, depending on the input to the select lines, I can simulate an LVDS interruption in my system.


Any thoughts? Are there any outright reasons this won't work?

Thanks.

  • TI__Mastermind 43795 points

    Benjamin,

    The SN65LVDS125A incorporates 25mV of input hysteresis (something not likely found on the ASIC Rx input).  Based on this, the 125A output response will not replicate shorts to GND or VDD, and the floating conditions found on the input side.  I think a direct test would be the best true test.  If you could place 0 ohm series resistors in the path, it would be possible to create the shorted and floating conditions you are looking for by modifying the board.  This way you would see how the actual ASIC Rx will deal with the fault conditions.

    Regards,

    Lee