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Trouble with TUSB551

Jason Aiello
Prodigy 20 points

Other Parts Discussed in Thread: TUSB551

Hello,

I designed a board using TUSB551 chip to redrive USB 3.0 signals. The board uses 2 chips. One to redrive the TX and one to redrive the RX. With a 1m cable on the input of the chips and a usb 3.0 thumb drive plugged directly into my board the redriver works fine. I get USB 3.0 speeds. However, if I add a 1m cable between the output of my board and the thumb drive, the drive is no longer detected. In this case I am floating the DE, OS, and EQ pins on both chips. Could it be related to the state of these pins? What do you recommend I should set these pins to with the above test setup?

thanks
Jason

  • 0
    TI__Mastermind 23815 points
    Hi Jason,

    TUSB551 on Rx side usually have a different configuration than TUSB551 on Tx side.
    The one on Rx side compensates for losses in cable, and boost the signal to send it to USB host.
    The one on Tx side compensates for losses in traces from host, and boost the signal to send it through the cable.
    Review datasheet section 9.2 Typical application for guidance on how to place and configure the two TUSB551.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 20 points

    Thanks for the reply. Here is another clue. I currently have the pins configured as the reference suggests. ie.. DE is pulled up on the Host RX side and EQ is pulled low the the Host TX side. The rest are floating.  The board I designed is a separate board in between the host and the client with 2 USB type A connectors on it to re-drive both the TX and RX signals.

    The re-driver works with 2 USB 1 meter cables in between the Host and the redriver board and a thumb drive directly plugged in to the output of the redriver board.. If I add a 1m cable in between the output of the redriver and a thumb drive it no longer works.

    Do you have any suggestions on how to configure the bits to give it a better chance of working?

    thank you

    Jason

  • 0 in reply to Jason Aiello
    TI__Mastermind 23815 points
    Hi Jason,

    If the board works with the thumb drive attached directly, but fails just adding a 1m cable, you may try different DE in TX path redriver and increasing EQ on Rx redriver.
    We recommend having placeholders for all configurations so customers can try all possible configurations and select the one the works best for them.

    Regards