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Original question:

ADC3422: PRBS generator of test data for LVDS interface

ADC3422: PRBS generator of test data for LVDS interface (bis)

Andrea Pastega
Prodigy 110 points
Part Number: ADC3422

I implemented the PRBS engine of previous thread some time ago.

Now I'm acquiring samples from a real chip, but these doesn't correspond to numbers generated by PRBS...

On original thread I noted that data value is obtained from a tapped [15:2] of the whole PRBS word, these are 14 bits... however ADC output is only 12 bits!

So I'm puzzled... I can't find a working solution for this.

Could you provide an example with expected values on 12bit output?

Thanks

Andrea

  • 0
    TI__Intellectual 2230 points

    Hi Andrea,

    I will double check with design team on this.

    I think there may be some confusion here as I believe the PRBS output isn't limited to 12 bits like the adc output. It could be possible you are seeing a correct output.

    Noting from the previous thread, did you try the toggle pattern that was recommended? If so, how does that look?

    I hope to have a response from design early next week and will update you on that no later than Tuesday.

    Best regards,

    Drew

  • 0
    Prodigy 110 points

    Hi Drew,

    alternate bit pattern and also ramp patterns are fine. 

    Thanks

    Andrea

  • 0 in reply to Andrea Pastega
    TI__Intellectual 2230 points

    Hi Andrea,

    Glad those work! Just to confirm, you are seeing 12 bits for PRBS output, correct?

    There might have been a mix-up on our end in the previous thread, we double-checked with design and the output should map to the MSBs of the original PRBS, i.e. PRBS[15:4].

    Best regards,

    Drew