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SN75DP126: EQ VALUES

GARETH OU
Mastermind 9875 points
Part Number: SN75DP126

Hi

When entering the OS, when the output is converted to DP, there will be 4K, but on the HDMI only 1080p

1.Now I2C is not set, can I directly use H/W to set different EQ values? How to set?

2.If I2C setting is recommended, what parameters are recommended?

PH370Q2_IMB4 _ 34_DDI3_TI-SN75D (002).pdf

  • 0
    TI__Guru**** 155021 points

    Hi,

    The EQ is being set through the SCL_CTL/EQ pin. When I2C_CTL_EN is low, this terminal can be used to configure the input EQ.

    You can then refer to Table 2 in the DP126 datasheet for the EQ configuration.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Mastermind 9875 points

    Hi David,

     Customer's block diagram is as below.

    1. They test DDI3 channel to TBT3 chip path and see 4K signal is ok.

    2. They test DDI3 channel through PI3HDX414 to HDMI out and get 1080p resolution with windows OS driver, but can see 4K resolution (maybe 4K 30Hz?) in bios mode and win 10 safe mode (without driver)

    3. They test PI3HDX414 EVM through DDI2 path and see 4K signal output on monitor.

    And customer set 18 dB mode by GPIO now as below.

     Due to we can't find EVM to confirm the 4K performance through SN75DP126 to HDMI path, do you have any idea to confirm the performance about 4K resolution in HDMI path? Or SN75DP126 can't support 4K in HDMI path?

    Regards,

  • 0 in reply to GARETH OU
    TI__Guru**** 155021 points

    HI,

    The SN75DP126 can support 4k@30Hz, it can not support 4k@60Hz. In this particular case, are we referring to 4k@30Hz or 4k@60Hz?

    The EQ needs to compensate for the loss between the DP126 and CFL-S, 18dB may be too large that you are over-equalizing the signal. What is the total trace length between the DP126 and CFL-S?

    Can you please use a scope and measure the clock input and clock output of the DP126? For 4k@30Hz, the expected clock frequency for both the input and the output is 300MHz.

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    Mastermind 9875 points

    Hi David,

    Just 4K@30Hz is enough.
    the specification mentions the following HDMI maximum data rate 3.4Gbps. Can this data rate support 4K30Hz?

  • 0 in reply to GARETH OU
    TI__Guru**** 155021 points

    Hi, 

    Yes, 4k@30Hz is 3.4G. For 3.4G, the EQ of 18dB is too high, you need to reduce the EQ to properly compensate for the loss between the DP126 and CFL-S. Otherwise you may run into the issue of over-compensation which will degrade the signal quality.

    Thanks
    David