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TMUXHS4446: Pin Connections in DRP Application

Ryan
Prodigy 60 points
Part Number: TMUXHS4446

Tool/software:

Hello,

I have a non-traditional application that needs to support DP in and DP out over a single USB-C connector.

My mux architecture involves the TMUXHS4446, but I would like to clarify how the connector-side pins connect to the system-side and DP pins. I saw that Table 6-3 and Table 6-4 give the pinouts based on if the mux is being used in a source or sink application. Since I'm not strictly following a source or sink application, I'm not sure how to interpret the table. From what I can tell, there is no way to tell the part it is in source or sink, so TI is trying to simplify the design by showing how to connect the pins to the connector to line up the DP lanes and USB signals.

What I would really like is a table that shows which pin numbers are connected for each of the CONF[2:0] modes.

For example, if CONFG[2:0] = 010, does pin 39 (DP0+) connect to either pin 34 (CRX2+, source) or pin 31 (CTX2+, sink)?

Thanks,

Ryan

  • 0
    TI__Guru**** 176561 points

    Ryan

    There is an app note, Type-C Alt Mode Application using TMUXHS4446 Crosspoint Multiplexer, that I believe will address your question. Can you please take a look at this app note and let me know if you need further clarification?

    You are correct that the TMUXHS4446 itself has no concept of source or sink. It is up to the PD controller to negotiate for the role of source and sink and then appropriately configure the TMUXHS4446 depends on the specific support of the Assignment implementation.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 60 points

    Hi David,

    I saw that app note, but was still a bit confused by table 3-1. I believe this table is trying to account for the lane flipping on DFP vs. UFP on the USB type-C connector. I'm really just interested in something isolated to the TMUX part on which pin number connects to which pin number depending on the config setting. 

    Is it safe to extract the pin numbers from the pin names from either table 6-3 or 6-4 from the datasheet?

    Thanks,

    Ryan

  • 0 in reply to Ryan
    TI__Guru**** 176561 points

    Ryan

    Yes, you can reference to Table 6-3 for the source side pin assignment and Table 6-4 for the sink side pin assignment. I took Table 6-3 and expanded it a bit as an example.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 60 points

    Hi David,

    I'm still confused by the statement of "Table 6-3 for the source side pin assignment and Table 6-4 for the sink side pin assignment."

    As a specific example, if I look at Table 6-3, CONF=010, I see that DP0 connects to CRX2. This would imply that DP0 (pins 39/40) connect to CRX2 (pins 33/34). But if I look at Table 6-4, CONF=010, it says that DP0 connects to CTX2. This suggests that DP0 (pins 39/40) connect to CTX2 (pins 30/31). Since the CONF register is the same (010) and the part has no sense of source or sink, 39/40 can't connect to both 33/34 and 30/31.

    Again, I understand that the datasheet is assuming we connect the TMUX part to the USB-C connector pins by matching the name. In doing this, the DP0 will naturally show up on the correct USB pair depending on if it is a source or sink. Since I'm not connecting the TMUX directly to a USB-C connector, I can't rely on the naming convention in the datasheet and would like to understand which pin numbers are connected together.

    Hope this helps explain my concern.

    Thanks,

    Ryan

  • 0 in reply to Ryan
    TI__Guru**** 176561 points

    Ryan

    I understand your confusion. Going back to Table 3-1 in the app note, 

    For source application, TMUXHS4446 CRX2 connects to Type-C connector SSRX2, CTX2 connects to Type-C connector SSTX2, CTX1 connects to Type-C connector SSTX1, and CRX1 connects to Type-C connector SSRX1.  

    For sink application, TMUXHS4446 CRX2 connects to Type-C connector SSTX2, CTX2 connects to Type-C connector SSRX2, CTX1 connects to Type-C connector SSRX1, and CRX1 connects to Type-C connector SSTX1 as shown below.

    You can also keep the connection between the TMUXHS4446 and the Type-C connector to be consistent between the source and the sink application, but swap the DP lane connection between the source side and the sink side application. 

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 60 points

    Can we ignore the naming convention and pin numbers of the Type-C connector and just focus on the internal switches and pins of the TMUX part? My architecture does not connect the CTX/CRX pins to a Type-C connector so that doesn't help me.

    From my previous example, if CONF=010, do pins 39/40 (DP0) connect to pins 33/34 (CRX2) or pins 30/31 (CTX2)?

  • +1 in reply to Ryan
    TI__Guru**** 176561 points

    Ryan

    DP0 pin (pin 30/40) is connected to pin 33/34.

    Thanks

    David