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Original question:

TUSB8044: Type C USB HUB Design Issues

TUSB8044: SBU Connection in a USB Type-C HUB

Eduardo Alves da Silva
Prodigy 170 points
Part Number: TUSB8044
Other Parts Discussed in Thread: TPS65987D, , HD3SS460, TUSB1064

Hello,

I'm trying to make a HUB circuit, with a full-featured USB Type-C as my Upstream port and, for Downstream, one full-featured USB Type-C port and a USB 3.0 Type A port. I've decided to use a TUSB8044 as the HUB circuit and the TPS65987D as the PD Controller, and I have been studying and figuring out almost everything, but I'm having issues with some connections.

1) As described below, I'm not getting exactly how to manage the SBU ports of both the Upstream and the Type C Downstream (See the picture below). Since I want a full-featured type C Downstream, I believe I need to connect both SBU ports from the Upstream connector to the Downstream one. Is this correct? The TPS65987D does not have any connections for SBU... 

2) I'm only using 2 of the TUSB8044 Downstream ports, but I'm not sure what to do with the other 2 DFP. Can I leave them not connected? Does it need to be pulled up/down?

  • 0
    TI__Mastermind 36751 points

    Hi Eduardo,

    The SBU lines will typically go to the superspeed mux of their respective port. Please keep in mind that SBU is only used for DisplayPort and not needed for USB3.0 only systems. If you want to split DP signals over multiple ports, you would also need an MST Hub in the system.

    If this answers your question, PLEASE select This resolved my issue

    Thank you,

    Eric

  • 0 in reply to Eric Beljaars
    Prodigy 130 points
    Hi Eric,

    Thanks for your response

    I work with Eduardo in this project. We want create a HUB USB what the upstream port is a USB type-C full featured and the downstream ports are a usb 3.0 type-A and other USB type-C full featured. So we need of the Display port Signal in only one port.

    I understood that the SBU signals go to a superspeed MUX. We want use the HD3SS460 chip, so is it a appropriate mux?
  • 0 in reply to Leonan França
    TI__Mastermind 36751 points
    Hi Leonan,

    In that case, you would need a superspeed mux on both Type-C ports. I would suggest looking at the TUSB1046 and TUSB1064 as they can support up to 10Gig and have built in redriver function.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 170 points

    Hello Eric,

    Thank you for your answer! I have been redesigning our circuit taking your answer into consideration, and I have come up with another block diagram of what might be the ideal solution for my application. The diagram is the following :

    Would this solution work? Also, it seems to me that there might be a way of using only one PD Controller, in a configuration like the following: 

    Would this be possible? In either case, what could be a reasonable choice for the PD Controller? Is the TUSB65981 a viable solution? If it's not, then why?

    Thank you for your time and patience,

    Eduardo

  • 0 in reply to Eduardo Alves da Silva
    TI__Mastermind 36751 points

    Hi Eduardo,

    Your first block diagram looks correct to me. You would still need two PD Controllers as each port would need to be able to negotiate PD contracts independently of one another. I would suggest looking at the TPS65987D as it is our newest PD controller and will be able to meet all of your requirements.

    If this answers your question, PLEASE select This resolved my issue

    Thank you,

    Eric