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TUSB8041: cascade connection

Eugene
Intellectual 260 points
Part Number: TUSB8041
Other Parts Discussed in Thread: TUSB4020BI, , TUSB8020B

Hi
I'm designing a USB HUB product.
My product requirements are following.
- USB3.2 upstream port x1
- USB3.2 downstream port x4
- a USB2.0 device in the product


I plan to use TUSB8041 but it doesn't have enough downstream ports for my requirements.
Therefore, I'm planning to use two HUBs in a cascade connection within the product.

Question : Is it possible to use TUSB8041 and TUSB4020BI as shown in "Block Diagram A" in the attached file?
   I know I can achieve what I want by using two TUSB8041 as shown in "Block Diagram B", but I'd like to keep the cost as low as possible.
   So I'd like to apply "Block Diagram A".
If you have any other good ideas, would you let me know?

  • 0
    TI__Guru*** 127345 points

    Hi Eugene:

        Diagram A will not work since USB3 and USB2 will not enabled at same time.

        for   Diagram B, you can change 1st hub to TUSB8020B so the cost will down a little bit. Also suggest 2nd hub to TUSB8041A which fixed some bugs in TUSB8041.

    Regards

    Brian

  • 0 in reply to Brian Zhou
    Intellectual 260 points

    Hi Brian

    Thank you for your help.

    Brian Zhou said:
      Diagram A will not work since USB3 and USB2 will not enabled at same time.

    In my understanding, general Host and Hub can operate both USB3 and USB2 at the same time.

    I referred to 11.1 and 11.2 in USB3.2 spec.

    Cannot TUSB8041A operate both USB3 and USB2 at the same time? 

    My concern was the topology is USB2 and USB3 have different topology in the product. I'm not sure it's allowed on USB spec.

    Brian Zhou said:
    for   Diagram B, you can change 1st hub to TUSB8020B so the cost will down a little bit. Also suggest 2nd hub to TUSB8041A which fixed some bugs in TUSB8041.

    OK, I'll use TUSB8020B and TUSB8041A if I apply Diagram B. Thank you.

  • +1 in reply to Eugene
    TI__Guru*** 127345 points

    HI Eugene:

       For diagram A: I talked with our system engineer and he think it will work too.  TUSB8041A can operate both USB3 and USB2 at the same time .

    Regards

    Brian