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TUSB4041I: Bus Powered vs. Self Powered Mode

Martin Seeger
Expert 5411 points
Part Number: TUSB4041I

Dear Team,

our customer is interested in using the TUSB4041.

Open topic is how to configure the device as bus-powered or self-powered?
If we understood the USB spec correctly, it is not only the question if the device is powered by VBUS, but it is also part of the USB negotiation?

Looking forward to your feedback.

Best Regards
Martin

  • 0
    TI__Expert 7395 points
    Hello Martin,

    That is correct, per USB specification device descriptors must report the device configuration (bus-powered vs. self-powered) and max VBus power consumption.
    In the case of the TUSB4041 this data is fixed reporting the device as a self-powered USB Hub with 0mA bMaxPower.

    Functionally you can configure the TUSB4041 as bus-powered, and it will have no issues; however it will not pass USB compliance tests since the descriptors will always report a self-powered configuration.

    Regards,
    Jorge
  • 0 in reply to Jorge Llamas (SWAT)
    TI__Expert 5411 points
    Jorge, appreciating your answer. This helped us with understanding the topic! Best Regards, Martin