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TUSB2E11: eUSB2 to USB solution

Jack Ni
Prodigy 80 points
Part Number: TUSB2E11


Hi TI experts,

eUSB2 to USB2 solution that was defined repeater so far. Does It mean the signal conditioning function is necessary for eUSB2 to USB2 design requirements?

If the difference between USB2 and eUSB2 is only voltage level, and the trace length is short in real design. Is "Re-driver" function still necessary? Can level-shifter be as solution for it?

Thanks.

Jack

  • 0
    TI__Mastermind 27925 points

    Hi Jack,

    Yes, you will need a repeater to have an eUSB2 port communicate with a USB2 port and you cannot replace it.

    The difference is not only the voltage level.  Since LS/FS is single-ended in eUSB, SE0/SE1 and a few other symbols are expressed differently, and that is also translated by the eUSB repeater to USB.  There are also command messages (CMs) and register access protocol (RAP) messages that are allowed to occur over eUSB, which are not defined in USB2.0.

    Regards,

    Nicholaus

  • 0 in reply to Nicholaus_Malone
    Prodigy 80 points

    Hi Nicholaus,

    Thank you for the explain.

    I can say this "Repeater" is more like as translator with level shifter and "re-driver" function is not must have on eUSB2 to USB2 product. Is it correct?

    Jack

  • 0 in reply to Jack Ni
    TI__Mastermind 27925 points

    Hi Jack,

    The eUSB specification is in the USB-IF document library: Document Library | USB-IF

    The signal conditioning "redriver" function is implied to be a requirement in the specification.  The way the spec defines those terms:

    Redriver - Analog Repeater
    Retimer - Retiming Repeater
    Repeater - General term of a bridge.  In this specification, it refers to a non-linear eUSB2-USB2 redriver.

    "A redriver is required to comply with Template 1 (in the case of host repeater) & Template 4 (in the case of peripheral repeater) as defined in USB 2.0, Section 6.1.2.2, when repeater signals" - Section 7.1.5.3 of eUSB specification.

    Regards,

    Nicholaus

  • 0 in reply to Nicholaus_Malone
    Prodigy 80 points

    Hi Nicholaus,

    Thank you for the information.

    I checked Intel eUSB2 document, they also highly recommend equalization capability in repeater’s transceiver design.

    I'm not sure if the below are the reasons, please advise.

    1. Loss concern because of swing is lower than USB2.0
    2. Full-speed/low-speed is single-end, it will be interfered easily.

    Jack

  • +1 in reply to Jack Ni
    TI__Mastermind 27925 points

    Hi Jack,

    The primary concern is loss.  The repeater actually has equalization capability on both the eUSB and USB sides of the repeater to help compensate for channel loss.  It's also needed so that the USB 2.0 signal passes electrical compliance. 

    The EQ settings on the eUSB side provides flexibility to work with various channel lengths and eUSB Tx/Rx architectures on the market, but if you'd like a more comprehensive list of reasons I can setup a meeting with a systems engineer to discuss. 

    Regards,

    Nicholaus

  • 0 in reply to Nicholaus_Malone
    Prodigy 80 points

    Thank you, Nicholaus.