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ADUM4165 and ADUM4166 fail in high-speed detection

Category: Hardware
Product Number: ADUM4166

I have a problem with ADUM4165 and ADUM4166 detecting high speed from some USB host ports. It seems that when it fails, the first K-chirp from the device on the downstream port is not copied to the host on the upstream port. In one case it fails with an 50 cm cable between the host port and ADUM4166, while it works with a short connection from the host port to ADUM4166.

Have anybody seen something like this case?

  • Hi Halvor,

    To assist us with this, can you clarify the following:

    • Have you seen this on some USB ports with all ADuM4165/ADuM4166 that you have, or just isolator boards/ICs?
    • Have you successfully used USB in high speed mode with the same ADuM4165/ADuM4166, when using different USB ports?
    • For the cases where you don't see the K-chirp being passed, could you share an oscilloscope plot?
    • For those cases, does the isolator operate in full-speed mode or is there no communication after the K-chirp isn't passed?

    Best regards,


  • Hi Conal

    I have made two prototypes, one with ADUM4165 and one with ADUM4166. Both behave in the same way.

    The work and go to high-speed mode on many USB host ports, f ex on a PC I have in the LAB.

    It works in full-speed mode if high-speed mode is not obtained.

    Do you have an e-mail address? I was not able to upload the files of scop pictures here. I can too send you the schematics and PCB layout of the prototypes.

    Best regards

    Halvor Liland

  • Hi Halvor,

    I've sent you an email; you can send the relevant details and we can discuss further.

    Best regards,


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