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TUSB8020B

Mickey Zhang
Genius 12080 points
Other Parts Discussed in Thread: TUSB8020B

Dear Sir,

I have a question of TUSB8020B.

When the upstream port is connected to an electrical environment that only supports Super-speed connections, then what about the downstream ports support? Below I have put two cases. Please let me know which one is true ? 

1.When Upstream is SuperSpeed USB only, then this Hub will support SuperSpeed USB connections only on the downstream ports and high-speed, full-speed/low-speed connections are disabled on the downstream ports.

2.When Upstream is SuperSpeed USB only, then this Hub will support all the SuperSpeed USB, high-speed, full-speed/low-speed connections on the downstream ports.

Thank you very much!

  • 0
    TI__Guru* 76130 points
    Hello,
    If you mean that the DP/DM lines in the Hub's upstream port are actually disconnected then the Hub will NOT support USB2.0 devices on its downstream ports.
    A USB hub does not translate between protocols, USB3.0 and USB2.0 are actually two different interfaces.
    Regards
  • 0 in reply to Elias Villegas M.
    TI__Genius 12080 points
    Thank you very much! If I have questions in the future , I will ask you.
  • 0 in reply to Elias Villegas M.
    TI__Genius 12080 points
    Our customer have some questions:
    You are correct "DP/DM lines in the Hub's upstream port are actually disconnected"
    I understand that TUSB8020BPHP USB hub does not translate between protocols.
    Is this limitation of this specific device ? Is there any other HUB which will translate USB3.0 and USB2.0 ?

    I have seen few other manufactures, which can support this translation. There is a Transaction Translator in the hub which helps in downgrading the speed from USB3.0 to USB2.0.
    Cypress HX3 USB 3.0 Hub CYUSB3302
    RenesaS Two-port USB3.0 Hub Controller μPD720211 ASSP

    Does Ti having similar device ? Can you suggest similar part from Ti ?


    Please reply as soon as possible.Thank you very much!
  • 0 in reply to Mickey Zhang
    TI__Guru* 76130 points

    Hello,

    You are misunderstanding, all the TI USB3.0 Hubs have multi-transaction translator, but you need to have the USB2.0 connection on the upstream port.

    That's why I asked you if the upstream USB2.0 will be actually disconnected, if there is no USB2.0 upstream connection none of the competitors you mention will support USB2.0 devices on the downstream.

    Regards