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TUSB8041A: Best way to achieve a 5 port (or more) USB 3.0 HUB ?

Jorge Miguel
Expert 1020 points
Part Number: TUSB8041A
Other Parts Discussed in Thread: AM5728

Hello,

I have the need of connecting 5 USB 3.0 devices to a USB 3.0 host (the host will be TI AM5728).

All USB HUBs that are listed on TI USB 3.0 HUBs product list are up to 4 ports

Is it possible to cascade connect two USB 3.0 HUBs so that I get more ports? Is there any drawback?

What other solutions can be designed?

Many thanks in advance

  • 0
    TI__Expert 7395 points
    Hello Jorge,

    The USB bus has a tiered start topology, where the center of each star is a USB hub; so, cascading USB hubs is essential on the USB bus topology.

    Only drawback on cascading USB Hubs is propagation delay, that is why the USB specification defined a maximum of 7 tiers (including the root hub); so you could have up to 5 daisy-chained hubs without issues. (I would recommend to have up to 4 daisy-chained hubs, otherwise USB compound devices won't be abe to enumerate behind the last/bottom Hub (as compound devices occupy two tiers)

    For additional details I would recommend you to check section 4.1.1 of the USB 2.0 specification (A USB3.0 hub consists of basically two separate hubs, one of them handles the SS traffic and the other handles HS traffic; so regardless of having a USB3.0 hub, limitation on the number of tiers is the same )

    Regards,
    Jorge Llamas