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TUSB8041: simultaneous USB2.0 and USB3.0 output?

Marion Loessl
Expert 3675 points
Part Number: TUSB8041

Hello everyone,

I have a specific question:

  1. Is it possible to output USB 2.0 and USB 3.0 signals simultaneously/ parallel?

For example:

IC1 is connected to Port 1 over USB 2.0 D+/D-.
IC2 is connected to Port 1 with USB3.0 to TX+-/RX+-.

If the above is possible, there are a few other questions:

2. is the following possible:

Additionally to USB 2.0 D+/D- (over Port 1 again), the USB 2.0 connector would use PWR/OC of Port 1 to "supply" the connector with 5V.

Like in the first scenario, IC2 is connected to Port 1 with USB3.0 to TX+-/RX+-.

3. What happens, if in the last scenario OC would be triggered and  TUSB8041 "deactivates" the PWR pin? Is there still an active connection to IC2 over USB 3.0? 

Kind regards,

Marion

  • 0
    TI__Guru 60870 points

    Hi Maroin,

    Yes, functionally this is possible.  If you connect a USB 3.0 hub to a downstream port of another USB 3.0 hub, both USB 3.0 and USB 2.0 traffic will be sent concurrently to whatever devices are connected to the hub.

    Can you connect a USB 3.0 device and a USB 2.0 device to the same downstream port of a hub?  We don't recommend it.  The devices will enumerate and traffic will be routed correctly, but as noted above, the two devices would share a single port power control.  Also, the USB specification requires all USB 3.0 devices have the ability to drop to USB 2.0 speeds.  Since the USB specification does not allow for two different speed devices connected to the same USB port, TI cannot guarantee that all USB drivers / host controller would support that implementation.   

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Expert 3675 points

    HI JMMN,

    thank you for your quick and detailed answer :)
    What do you mean by "but as noted above, the two devices would share a single port power control"?

    Can the 2 devices also be independent from each other?

    So that no matter what the Port Power Control does (f.e. deactivate due to overcurrent), the communication over USB3.0 is running?

    Kind regards,

    Marion

  • 0 in reply to Marion Loessl
    TI__Guru 60870 points

    Hi Marion,

    The original question outlined some of the concerns about sharing a port power control / over current for two devices.  The port power control / over current is shared on a port between USB 2.0 and USB 3.0, as described in the USB 3.x specification and there is no way to make them independent.  Also, when a hub reports an over current condition to the host controller, it is up to the host controller to stop or continue traffic.  Most host controllers will actually stop traffic to the entire hub and all connected devices if an over current condition is reported.

    Regards,

    JMMN