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TMDS1204: Technical Inquiry Regarding TMDS1204 with Low-Amplitude Input Signals

Ouchi Tomoya
Prodigy 10 points
Part Number: TMDS1204


Tool/software:

Dear Texas Instruments Technical Support

I am considering using the TMDS1204 redriver IC and would like to confirm the following points:
1. Regarding low-amplitude input signals:
- The specification for input differential voltage (VID(DC)) is 400mV to 1200mV, but how would the device perform with low-amplitude differential signals of approximately 160mV to 280mV?
- Is it possible to properly amplify such low-amplitude signals to achieve differential output signals of 400mV or higher?

2. Regarding signal detection function:
- According to the datasheet, the signal detection assert level (VRX_ASSERT) is 180mVpp and the deassert level (VRX_DEASSERT) is 110mVpp.
  Are these values adjustable?
- Will the signal detection function operate reliably with input signals of 160mV to 280mV?

  • 0
    TI__Mastermind 20276 points

    Hi Toyoma-san, 

    Because TMDS1204 is a linear redriver, it can take any signal within the linearity range and output it. So, it will still work with low-amplitude differential signal that you described. 
    You can amplify such low-amplitude signal by putting the redriver in the limited mode and change the TX swing. But please note since your signal amplitude is 160mV to 280mV, below the TMDS1204 min of 400mV,  you will not able to have the full gain amplification. We also did not characterize the TMDS1204 input below the 400mV, so we honestly do not know how much gain you will have when the input amplitude is below 400mV.
    The signal detection assert level is not adjustable. 
    Because your signal is right around the level, I do not recommend to use the signal detection function. 

    Best,
    J