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TMDS181RGZEVM: Not working with some 4K sources

kenick kim
Prodigy 140 points
Part Number: TMDS181RGZEVM
Other Parts Discussed in Thread: TMDS181

Hello,

We are testing with EVB and found some issues.

<common setting>

1. Lane / Polarity Swap = Disabled

2. Clock Input Signal Detector = Enabled

3. HPD_AUTO_PWRDWN_DISABLE = Disabled

4. Device Function Mode = Retimer Mode across full range 250Mbps - 6Gbps

<question>

1.On 3840x2160 UHD and 4096x2160 4K resolution

- TMDS_CLOCK_RATIO -> 1/10 of TMDS bit period

- HDMI Clock Rate -> 300MHz

** We can read above status and cannot see any video on the sink with a 4K setop box.

** From the PLL status it togges lock and unlock irregularly.

** It is OK without the EVB.

Can TMDS181 work with 4K resolution? Is there any limitation?

2. Is it possible to tansmit 4K resoution with TMDS Clock Ratio 1/10 of TMDS bit period?

3. What is a right value for transmit termination when the source is 4K and TMDS clock ratio 1/10.

- No termination? or 150 to 300 ohm?

Regards

Kenick

  • 0
    TI__Expert 5455 points
    Hello Kenick

    1.- It is possible if the Data Rate is inside of the parameters of the device, our device support up 6 Gbps per lane (up to 18 Gbps)
    2.- It is possible if the Data Rate is inside of the parameters of HDMI1.4, in case of version b, it supports up to 3.4 Gbps.
    3.- It depends on the Refresh Rate, color bit depth, chroma sampling, and standard, If all of these parameters are inside of the Data Rate, it is possible. But for this resolution, I recommend you to use HDMI 2.0.
    4.- For termination resistor, please, check TX_TERM_CTL (page 6) but I recommend you let no connected because, with this one, the device selects the termination impedance automatically.

    Regards
    Francisco