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TUSB564: Pre-emphasis and output swing level of DP

Antony Lin
Genius 13480 points
Part Number: TUSB564

Hi

I have some questions about Pre-emphasis and output swing level of DP in TUSB564.

In TUSB564 datasheet, I can't see any configurability of pre-emphasis in TUSB564, I think that means TUSB564 can't impact pre-emphasis in any way and pre-emphasis should depends on the link training result between DP source and DP sink , right?

Regarding output swing level, I see we define "VOD dynamic range " as 1300mV (typical) in the datasheet.  What does this number means for the chip?  DOes it mean a maximum/saturation level that TUSB564 would not output the DP signal higher than 1300mV peak-to-peak?  Or anything else?  I can't see any configurability to the output swing level in TUSb564 datasheet as well.  Could you explain how we decide the output swing level in this chip?

Thanks,

Antony

  • 0
    TI__Guru**** 156171 points

    Antony

    Since TUSB564 is a linear redriver, it does not have any TX SWING or Pre-emphasis control. The control has to come from the source itself and the source may have to boost output swing and pre-emphasis to compensate for the DC(swing) and AC(pre-emphasis) loss across the trace.

    For the VOD dynamic range, it defines the TUSB564 RX linearity range. If the input signal amplitude is within the TUSB564 linearity range, the output signal amplitude will be almost one to one ratio to the input signal amplitude. But if the input signal amplitude is outside the TUSB564 linearity range, then the output signal amplitude will be clamped around 1.3V.

    Thanks

    David