• State TI Thinks Resolved
  • Locked Locked
  • Replies 13 replies
  • Answers 6 answers
  • Subscribers 33 subscribers
  • Views 701 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TUSB8042A: Does 5Gbps means 5Gbps in total or 5Gbps for each port?

Hung Ching Hsu
Expert 3086 points
Part Number: TUSB8042A
Other Parts Discussed in Thread: TUSB320, TUSB322, TUSB321, TUSB542, HD3SS3212, TUSB322I

Hi Team

My customer has three questions about TUSB8042A.

1. When USB2.0 memory is connected to USB hub, how will USB hub know if the memory is 2.0? E.g., will USB send signal to USB hub to tell USB hub that the USB memory is 2.0 or inversely USB hub will send a signal to memory?

2.  When USB2.0 memory is connected to one port of USB hub, will other ports still maintain USB3.2 or other ports will also became USB2.0?

3. Does 5Gbps means 5Gbps in total or 5Gbps for each port?

Please let me know where is it if I can find the answer for above question in datasheet. 

Thanks.

Regards,

Jo

  • 0
    TI__Guru 60870 points

    Hi Jo,

    1. The USB 2.0 memory will connect on the USB 2.0 lines (USB DP/DM) to the hub, not the USB 3.0 lines (USB SS) so the hub will connect at USB 2.0 speeds to the memory.

    2. The speed of one downstream port does not impact the speed of the other downstream ports.  Only the upstream port speed impacts the downstream port speeds.  If the upstream port is connected at USB 2.0, the downstream ports can only support USB 2.0 speeds.  If the upstream port is connected at USB 3.0 speeds, the dowsntream ports can support USB 3.0 or USB 2.0 speeds.

    3. The bandwidth of the USB 2.0 bus and the USB 3.0 bus are separate, but each one is shared between the downstream ports.  The USB host handles the traffic scheduling.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3086 points

    Hi JMMN

    Thanks for the reply. 

    Could you confirm if I'm understanding it right for question 3? Thanks.

    So total bandwidth of USB 2.0 bus is 480Mbps and USB 3.0 is 5Gbps. If 2 USB 3.0 memory and 2 USB 2.0 memory is connected to USB hub, the speed for each USB 3.0 memory will be shared from 5Gbps and speed for each USB 2.0 memory will be shared from 480Mbps. And how much speed each device have depends on USB host controller.

    Regards,

    Jo

  • 0 in reply to Hung Ching Hsu
    TI__Guru 60870 points

    Hi Jo,

    Yes, your understanding of the USB bandwidth is correct.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3086 points

    Hi JMMN

    Thanks for the confirmation.  

    Let me ask you one more question. 

    Customer wants to connect TUSB8042A with Type C device for data transferring. 

    To connect Type C device, which line(CC1 or CC2) to use should be decided depends on the connect direction, customer wonders if TUSB8042A has this kind of function? 

    I looked up TUSB8042A and I don't think TUSB8042A supports for Type C device. 

    Just to make sure, could you help confirm if TUSB8042A supports for Type C device?

    And if not, can customer connect Type C USB to TUSB8042A by adding additional IC or he needs to choose other IC if he wants to connect Type C device to Hub?

    Thanks.

    Jo

  • 0 in reply to Hung Ching Hsu
    TI__Guru 60870 points

    Hi Jo,

    The TUSB8042A can be used in a Type C application, but it will require an SS mux and a CC controller depending on the application.  Please check out the TUSB320 device and other offerings here:  

    www.ti.com/.../products.html

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3086 points

    Hi JMMN

     

    Just to confirm, so when customer wants to connect Type C device to TUSB8042A, customer needs at least one CC controller like TUSB320 to tell TUSB8042A which side of type C device(has type C connector, such as USB memory) is connected to TUSB8042A ?

     

    Regards,

    Jo

  • 0 in reply to Hung Ching Hsu
    TI__Guru 60870 points

    Hi Jo,

    The TUSB80402A is not Type-C aware, so the CC controler and SS MUX must be configured to route the USB 3.0 signals to the hub.  See this application note for more information:    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3086 points

    Hi JMMN

    I looked up about USB a little more. 

    So if type C connect to USB2.0, only CC controller will be needed.

    If type C connect to USB3.1 , CC controller and SS MUX will be needed.

    Is above correct? 

    If above is correct, since customer is considering connect type C device to USB3.1, and JMMN has introduced TUSB320 for CC controller, can you recommendation for SS MUX works well with TUSB8042A?

    And also is there any sample schematic for usage of TUSB8042A+TUSB320 and CC controller when connecting to type C device? 

    Customer wants to know how actually is these three devices works together. 

    Besides, do TI have 4 port(downstream) USB Hub supports USB3.1 Type C? Customer uses USB3.1 Type C for only one port. 

    Sorry for asking several questions at once. Your help will be appreciated.

    Regards, 

    Jo

  • 0 in reply to Hung Ching Hsu
    TI__Guru 60870 points

    Hi Jo,

    Yes, the mux is only needed for USB 3.1 ports.  TUSB320 is a good CC controller for a USB 2.0 Type-C port, but TUSB321 or TUSB322 can be used as the CC controller for a USB 3.1 Type-C port.  For the mux TUSB542 or HD3SS3212 can be used, please check the part selector here for more information:  

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3086 points

    Hi JMMN

    Thanks for the reply. 

    Is the only difference between TUSB321 and TUSB322I is that TUSB322I supports I2C? Is there any difference between these two devices?

    And the difference between TUSB542 and HD3SS3212, am i understanding it right if customer needs better signal integrity, customer should use TUSB542. And if signal integrity not a problem here, they can just use HD3SS3212? Is there any difference between these two devices?

    Could you tell me if there's any other significant differences between TUSB321&TUSB322I and TUSB542&HD3SS3212?

    Thanks.

    Regards, 

    Jo

  • 0 in reply to Hung Ching Hsu
    TI__Guru 60870 points

    The main difference between the TUSB321 and the TUSB322 is the GPIO support vs. I2C support.

    The main difference between the TUSB542 and the HD3SS3212 is that the TUSB542 has redriver functionality that the HD3SS3212 does not.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3086 points

    Hi JMMN

    Thanks for the reply. 

    Regarding TUSB542, my customer is asking how do they know if they need a redriver or not.

    I looked up some materials and seems it depends on if the loss budget of customer's system meets USB specification or not.

    Do we have any material that can help customer calculate loss budget in their usage?

    Or what kind of information do we need from customer so we can confirm loss budget for them?  

    Since customer is still configurating their system so the information may be limited. 

    Your help will be greatly appreciated.

    Regards, 

    Jo

  • 0 in reply to Hung Ching Hsu
    TI__Guru 60870 points

    Hi Jo,

    This white paper helps to explain the loss budgeting for USB 3.x systems:  

    Regards,

    JMMN