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Original question:

66AK2G12: USB VBUS input

66AK2G12: USB Connection in HOST and DualRole

Naoki Kawada
Guru 19890 points

Part Number: 66AK2G12

Hi,

My customer is designing their custom board and now have some question about USB connection in HOST and DualRole.

As for the typical connection, they have referred the following document :

But rather than the suggestions described in the document, they are wondering if they could go with the following scheme:

Here, 5V_USB is powered by local 5V regulator and 5V_VBUS (for external device) is powered by another and specific regulator. Could you comment if that is still allowed in design ?

Best Regards,
NK

  • 0
    TI__Mastermind 25170 points

    Hi Naoki Kawada-san,

    Unless you have a good reason, please do route VBUS to VBUS-sense. That way USB controller and driver "will know" for possible failed VBUS.

    On your diagram, you are tricking the controller that 5-V are always present , which is the normal condition for USB host, so the controller *might* work. Again this is not recommended and I cannot say this is ok in all cases.

    Also, please note that with USB-A connector, controller may work in USB host only. DRD is not possible.

    Regards,

    Stan

  • 0 in reply to Stanislav Stilyanov
    Guru 13660 points
    Hi Naoki Kawada-san,

    As suggested by Stan, if you use VBUS-sense, then you can use DRVVBUS pin of K2G to enable the regulator, instead of from a GPIO(assuming the line going from K2G to VBUS SW regulator is enable)
  • 0 in reply to Dwarakesh Radhakrishnan
    TI__Guru**** 161600 points
    Hi,

    I confirm that the recommended connection of the USB is described in the Schematic Checklist). If you choose to go with a design that is different you will have limited support in the future.

    Best Regards,
    Yordan