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TUSB4041I: how to build 7 port by this part?

James Zhan
Expert 4365 points
Part Number: TUSB4041I


Hi team,

My customer want to have a 7 port USB2.0 with speed of 480Mbps, could we use two TUSB4041I to build it?

Or do you have other recommendation part?

Thanks,

James 

  • 0
    TI__Guru 60870 points

    Hi James,

    Yes, the TUSB4041 devices can be tiered by connecting the downstream port of one hub to the upstream port of the second hub.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 4365 points

    Hi JMMN,

    Do you have a recommendation circuit? 

    Does this kind of connection would have any potential risk? Would it slow down the speed?

    Thanks.

  • 0 in reply to James Zhan
    TI__Guru 60870 points

    Hi James,

    The USB specification allows for up to 5 tiers of hubs.  Tiered hubs are very common applications with no risk and no noticeable impact on throughput / propagation delay.  Please note that for the USB_VBUS signal of the second tier hub, it should be either controlled by the power switch of the first tier hub (ideal) or connected to the USB_VBUS of the first tier hub.  It should not be left permanently pulled high.  We do not have a reference design, but we can review the customer's schematic.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Intellectual 1635 points

    Hi JMMN,

    For tiered application for example 7 port here, what's the scheme that the second tiered hub communicate with the host? Is the speed still 480Mbps for each port? Or is it time multiplexed so each port has limited time to stream data to the host?

    Thanks,

    George

  • 0 in reply to George Zhao
    TI__Guru 60870 points

    Hi George,

    Yes, the hub to hub connection will be at 480 Mbps (high speed).  Any connected devices will connect at whichever speed they support (high speed, full speed or low speed)  and the hub will translate between the full speed / low speed devices and the high speed bus. 

    The host schedules the data transfers to/from the devices, USB isn't time multiplexed.  

    Regards,

    JMMN