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TDP1204EVM: DDC Buffer

Dan Itan
Prodigy 20 points
Part Number: TDP1204EVM
Other Parts Discussed in Thread: TDP1204

Tool/software:

Hi,

From the scheme it looks like SDA_SINK and SCL_SINK are connected to both HDMI TX and HDMI RX connectors.

In this way the TDP1204 DDC buffer will not come into play no matter which resistor is connected...

The LV_SCL_SRC and LV_SDA_SRC lines from TDP1204 are not going to either of the HDMI connectors.

Am I missing something?

Thanks,

Dan

  • 0
    TI__Guru**** 177866 points

    Dan

    Your understanding is correct. Since the DDC bus is passing between the source and the sink, and both the source and the sink support 5V DDC signaling, then there is no need to use the TDP1204 DDC buffer. In this particular case, TDP1204 is snooping the DDC bus using its HV_DDC_SDA and HV_DDC_SCL.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 20 points

    Thanks for the quick response David!

    A few more questions if you don't mind:

    1. So if the source in my design support 3.3V, I need to add level shifter to 5V before the EVM, right?

    2. If I integrate TDP1204 in my design (just the component) I could use its internal DDC buffer instead of a level shifter, connecting LV side to the source and HV to the sink, right?

    Thanks

    Dan  

  • 0 in reply to Dan Itan
    TI__Guru**** 177866 points

    Dan

    Please see my inserted response

    1. So if the source in my design support 3.3V, I need to add level shifter to 5V before the EVM, right?

    Correct, you can use the TDP1204 internal level shifter or external I2C buffer/level shifter.

    2. If I integrate TDP1204 in my design (just the component) I could use its internal DDC buffer instead of a level shifter, connecting LV side to the source and HV to the sink, right?

    Correct, in this case, the TDP1204 VIO will be set to 3.3V as well. 

    Thanks

    David