• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 33 subscribers
  • Views 1237 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TI recommendation for HDMI DDC/CEC buffer.

Kawai
Guru 19775 points
Other Parts Discussed in Thread: TCA9517

Hello Team,

Could you please give us recommendation which buffer to use in HDMI DDC and CEC line ?

The object is to pass HDMI CTS (compliance test spec) of DDC/CEC capacitance requirement.

I believe
- TXSxxxx / LSFxxxx series is a switch type so this device cannot isolate capacitance on A side and B side.
- TXBxxxx series is a buffer type, however, cannot meet the current requirement.

Best Regards,

Kawai

  • 0
    TI__Guru* 76130 points
    Hello,
    You may use a I2C buffer, I'm moving this to I2C Forum.
    Regards
  • 0 in reply to Elias Villegas M.
    TI__Genius 17245 points

    Hello Kawai,

    We recommend the TCA9517.  See the below post to give you additional information about the implementation of the device.

    https://e2e.ti.com/support/interface/i2c/f/390/t/540657

    -Francis Houde

  • 0 in reply to fhoude
    Guru 19775 points

    Hello Francis-san,

    Thank you for the information.

    I looked into the post in the above link and found below information.

    The TCA9517 has been used in the past for HDMI DDC channel.
    My only recommendation is to do 1 of the following:
    1) Connect the A side of the TCA9517 to the HDMI cable if possible (static voltage offset has caused weird issues with compliance test, and doing this will avoid those issues).
    2) Have a detection scheme that will pull EN to GND while doing compliance testing.
    The compliance testing would normally be done while TCA9517 is enabled, which will send false data on I2C bus unless EN is pulled to ground. this false data has caused issues with other customers.

    I understood that TCA9517 could be used as long as A-side is connected to the connector.

    I have questions for description 2).

    Q1) is this information for when B-side is connected to the connector ?

    Q2). Why would you need to disable the device and what is it expected to detect ?

    Q3). What do you mean by "false data" ? could you please explain in specific ?

    HDMI CTS must be done with the real system operating design. User cannot use some trick to pass the compliance testing.(maybe they could but it is not the right way.)

    Best Regards,

    Kawai