Keep EDID data ADV748X only with 5V via HDMI connector

Dear Sir/Madam,

Can I keep ADV748X EDID data in EDID RAM if system only provides 5V power via HDMI connector, and the other power are all power down? 

If I can't keep those data with HDMI 5V, how would you suggest me to do in order to pass HDMI certification item (Test ID 8-1) which requires that EDID can be read after powering down for general case.

Thanks very much!

Henry

  • Hi,

    Before moving in to your question, Could you please answer the following?

    1. Do you have one of our evaluation board for ADV748X?

    2. How do you configure the board?

    3. Are you using any specific script from ADV748X design support files?

    4. Did you do the test on evaluation board and observe same behavior?

    Best Regards,

    Jeyasudha.M

  • Hi Jeyasudha.M,

    Thanks for your feedback, but unfortunately I don't have that EVB on hand. 

    Thanks!

    Henry

  • Hi Jeyasudha.M,

    Here's test scenario :

    1. Power ON ADV7481 and master will write EDID data to ADV7481's EDID RAM

    2. Connect HDMI Tx with HDMI Rx through HDMI cable, and Tx side will read ADV748X EDID data

    3. Power OFF ADV7481 but there's still 5V on HDMI cable from HDMI Tx

    4. Tx side will read ADV7481 EDID data again and compare with EDID date we read in step.2 to check whether is the same.

    Like ADV7623 specify as below, but it is not listed in ADV7481 datasheet : 

    So may need your help to confirm whether can ADV7481's EDID RAM keep data after main power down but HDMI 5V still exist, thanks!

    Best Regards,

    Henry 

  • Hi,

    We are checking with part specialist and update you.

    Best Regards,

    Jeyasudha.M

  • Hi,

    The data in the EDID will not be maintained in the EDID RAM if the supplies to the ADV748x are not provided. Please see Section 5.3.1.4 in the Hardware Manual:

    The E-EDID/repeater controller is reset when the DVDD supplies go low or when hdcp_rept_edid_reset is set high. When the E-EDID/repeater controller reboots, it performs the following tasks:

    • Clears the internal E-EDID and Key Selection Vector (KSV) RAM (refer to Section 5.3.8.2)
    • Computes a checksum

    Test ID 8-1 in the CTS spec states that after powering down the Sink DUT and still applying the 5V signal on the HDMI connector, the EDID should be read if the sink asserts HPD. The ADV748x will not assert HPD if the supplies are not provided to it. So the EDID will not be read when the Sink is powered off.

    Best Regards,

    Jeyasudha.M