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TMDS181: Variation of VSWING_DATA control

S.Satoshi
Guru 21685 points
Part Number: TMDS181

Hi,

Please let me ask about VSWING_DATA control. I know that we can increase and decrease output swing with 7% step via VSWING_DATA register, then I'd like to know the variation of this 7% step. The estimated rough value should be OK, so can you ask your design team about it?

Best Regards,

Satoshi / Japan Disty

  • 0
    TI__Guru**** 178126 points
    Satoshi-san

    Why do you need to know the variation of VSWING_DATA? Unfortunately, this is data that we do not have.

    You would get a bigger variation by changing the VSADJ resistor, the variation across VSWING_DATA would be very small.

    Thanks
    David
  • 0 in reply to David (ASIC) Liu
    Guru 21685 points
    Hi David,

    Thank you for your comment.

    We would like to adjust Pre-emphasis peak amplitude by tweaking the register value rather than VSadj. Because it is much easier than changing resister value dedicated to the ASadj. (I want to know the relative change of the amplitude rather than absolute validation,
    when resister value is changed,)

    In order to implement pre-emphasis function, it is crucial to know how precisely control the peak amplitude.

    Best Regads,
    Satoshi
  • 0 in reply to S.Satoshi
    TI__Guru**** 178126 points
    Satoshi-san

    There is a 20mV change in signle-end output voltage swing per 100ohm delta VSADJ. To tune the signal amplitude, you primary knob is the VSADJ, then for you can tune the register setting on top of VSADJ setting. Unfortunately, I don't have the data for VSWING_DATA variation.

    Thanks
    David