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TUSB214-Q1: Should Redrivers be used as a pair for long distances?

Jamie Milliken82
Prodigy 110 points
Part Number: TUSB214-Q1
Other Parts Discussed in Thread: TUSB212-Q1, TUSB216

We have an application that will be transmitting USB 2.0 over ~15ft and also in the presence of some power supply and motor noise (though the twisted pair with the USB signals will be shielded). To mitigate potential signal integrity issues, we are looking at using the TUSB214-Q1. However, my question is whether it is a good idea to actually use two of these - one at the host and another at the device end?

Thank you.

  • 0
    TI__Guru 64326 points

    Hi Jamie,

    TUSB214-Q1 (and other USB 2 redrives) can help with losses form long USB 2 cables in noisy environments it may be best to only use one to ensure noise from EMI is not boosted. You can also use TUSB212-Q1, package option here allows for device to be left not populated if the redriver is not needed.

  • 0 in reply to Malik Barton57
    Prodigy 110 points

    Thank you Malik. I will look into the TUSB212-Q1 as that would be nice to have a option to depopulate it on one side and test different configurations. In the case that we only use one, is there a preference for putting it on the host side vs the device side?

    Thanks,

    Jamie

  • 0 in reply to Jamie Milliken82
    TI__Guru 64326 points

    Hi Jamie,

    I would recommend keeping them farther away from the main source of the potential EMI. Since you are looking to support longer cables having TUSB212-Q1 on both sides would be best. Our latest redriver, TUSB216, could also be used to support longer cables and has a better chance of being able to maintain signal integrity from only the host side (same package as TUSB212-Q1 but smaller allowable temperature range). Recommended TUSB212-Q1 for the package and extended temperature range.  

  • 0 in reply to Malik Barton57
    Prodigy 110 points

    Great. Thank you for the quick response.

    -Jamie

  • 0 in reply to Jamie Milliken82
    Prodigy 110 points

    One follow-up question - the datasheet specifies that the traces should run continuously under the part so that it can be depopulated or powered down without losing the USB connection. I'm not sure I understand this. Isn't there some zero Ohm jumpers that would need to be depopulated so that the signals run through the IC rather than shunt underneath? How is it effective if there are traces directly connecting input to output?

    -Jamie

  • 0 in reply to Jamie Milliken82
    TI__Guru 64326 points

    Hi Jamie,

    This is correct,  TI USB 2 redrivers are designed to allow for this kind of routing. This allows for a clear design and eliminates stubs that would appear from using extra path and 0 ohm resistors. I would recommend getting a EVM for initial testing, as they say seeing is believing. Referring to the EVM could also be of some use. Sorry I cannot share too many details here as this is protected IP.