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Original question:

Recommended Display Port Chip

HD3SS214: HD3SS214IZQER

Ramgopal Divakar
Expert 1300 points
Part Number: HD3SS214

Hello,

please refer to the figure below. 

I am connecting HD3SS214IZQER as a 1:2 display port demux to switch my MXM module display port lanes either to USB type C circuit or a test HDMI connector.

HD3SS214IZQER datasheet section 7.1 has a note stating there is no common mode biasing. I want to make sure I got the decoupling caps right with respect to DP lanes. Port C of HD3SS214IZQER connects to the MXM module via decoupling capacitors. Port A connects directly (no caps) to TUSB1046AI-DCI USB type C/DP switch. Port B directly (no caps) connects to HDMI level shifter NXP PTN3360DBS which connects to the HDMI connector.  Is his okay for the 4 differential lanes and AUX lanes?

AUXP/AUXN channels of port B are pulled up close to the HDMI level translator to 3.3V and AUXP connects to SCL while AUXN to SDA. Is this correct?

Can I pull down DDC channels on ports A/B/C of HD3SS214IZQER  since I am not using it?

HD3SS214IZQER  table 1 says I must make AUX_SEL:DxSEL as 00 or 01 to switch port C to port A or port B. However section 8.2.3.2 says it differently where AUX_SEL is used to switch the AUX lines between A to C or B to C. Which is right?

  • 0
    TI__Guru**** 178046 points

    Please see attached block diagram

    PTN3360 is a passive DP++ to HDMI level shifter, but DP++ is not supported with Type C. Type C only supports DP. For DP to HDMI, you would then need an active protocol converter, not a level shifter.

    DDC of HD3SS214 can be left floating if not used.

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    Expert 1300 points

    Hey David,

    just to be clear, I am using a USB PD controller that communicates via I2C with TI TUSB1046AI-DCI. It is using caps on TXP ports and not RXP ports per application schematic. Also the AUX P and N has the pull down and up like you suggest. So am I good to go here?

    We have directly connected the MXM (via AC caps) to PTN3360 to HDMI and it worked in the past. I am now inserting the HDSS214 in between which led me to these questions.

    So am I good to go on the HDMI side? Or do I need to change anything?

    The HDMI is just a test case during initial debug before we get the USB type C to work.

    How can I send you a schematic just to be sure?

    Thanks,

    Divakar

  • 0 in reply to Ramgopal Divakar
    Expert 1300 points

    And also,

    answers to these:

    HD3SS214IZQER  table 1 says I must make AUX_SEL:DxSEL as 00 or 01 to switch port C to port A or port B. However section 8.2.3.2 says it differently where AUX_SEL is used to switch the AUX lines between A to C or B to C. Which is right?

    AUXP/AUXN channels of port B are pulled up close to the HDMI level shifter to 3.3V and AUXP connects to SCL while AUXN to SDA. Is this correct? When we directly connected the MXM to PTN3360 this is how we hooked it up. Now we are going through HD3SS214IZQER. I do understand on the USB type C side AUX P is pulled down and AUX N pulled up.

  • 0 in reply to Ramgopal Divakar
    TI__Guru**** 178046 points

    ivakar

    just to be clear, I am using a USB PD controller that communicates via I2C with TI TUSB1046AI-DCI. It is using caps on TXP ports and not RXP ports per application schematic. Also the AUX P and N has the pull down and up like you suggest. So am I good to go here?

    Yes, please make sure 220nF cap on TXP/N. Cap on RXP/N is optional, if needed, please use 330nF.

    We have directly connected the MXM (via AC caps) to PTN3360 to HDMI and it worked in the past. I am now inserting the HDSS214 in between which led me to these questions.

    So am I good to go on the HDMI side? Or do I need to change anything?

    Yes

    HD3SS214IZQER  table 1 says I must make AUX_SEL:DxSEL as 00 or 01 to switch port C to port A or port B. However section 8.2.3.2 says it differently where AUX_SEL is used to switch the AUX lines between A to C or B to C. Which is right?

    Please follow Table 1

    AUXP/AUXN channels of port B are pulled up close to the HDMI level shifter to 3.3V and AUXP connects to SCL while AUXN to SDA. Is this correct? When we directly connected the MXM to PTN3360 this is how we hooked it up. Now we are going through HD3SS214IZQER. I do understand on the USB type C side AUX P is pulled down and AUX N pulled up.

    Why not have DDC of Port B connected to PTN3360, and have AUX of Port C connected to MXM?


    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Expert 1300 points

    Thanks,

    is there a way I can have the schematics looked at? How can I email it?

    Divakar

  • 0 in reply to Ramgopal Divakar
    TI__Guru**** 178046 points

    Divakar

    Please accept my friendship request, and then you can send me the schematic in a private message.

    Thanks

    David