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TPS25750: The purpose of 'What is the supported USB Highest Speed?' in TPS25750 Application Customization Tool

diverger
Expert 1275 points
Part Number: TPS25750

Hi,

In the customization tool, there is a option "What is the supported USB Highest Speed?", what will affect the behavior of the TPS chip?

Thanks.

  • 0
    TI__Mastermind 34506 points

    Hi Hua,

    Based on the selection here, the PD will respond with the USB speed supported after power negotiation. If your device does not require to support USB data, select "No USB data is being used". 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Expert 1275 points

    Hi,

    I find that even I set the speed to USB2.0, it can also communication with USB3.0 device, will it automatically transform from USB2.0 to USB3.0?

    Thanks.

  • 0 in reply to diverger
    TI__Mastermind 34506 points

    Hi Hua, 

    USB3.0 is backward compatible with USB2.0 so seeing communication occur is normal, however the USB2.0 device should not be able to "automatically transform from USB2.0 to USB3.0". Can you elaborate how this was tested (what kind of device is connected, is the PD sourcing/sinking, etc.), how are you able to see communication occur, and if there's PD logs of this transaction? 

    Can you also send your JSON config from the Online Application Customization Tool? 

    Thanks and Regards,
    Raymond Lin

  • 0 in reply to Raymond Lin
    Expert 1275 points

    Hi,

    So you means if I set the highest speed supported to USB2.0, it can only 'talk' using USB2.0 protocol? We used a USB3.0 USB disk to the simple test. In this situation the USB device may run under compatible mode and talk with USB2.0 protocol too, right?

    Thanks.

  • 0 in reply to diverger
    TI__Mastermind 34506 points

    Hi Hua, 

    This is dependent on the USB hub on the system with the TPS25750. The TPS25750 will simply advertise the USB data capability to a connected device via cable. During the "Discover Identity" portion of the PD negotiation process, based on the selection you made in the Application Customization Tool (Question 5 "What is the supported USB Highest Speed?") the TPS25750 will respond with the supported USB data speed to let the far-end device know what USB data speed is supported. How the internal USB host/hub device communicates via USB protocol is separate from the PD controller. 

    Typically USB 3.0 is is backward compatible, meaning if a USB 2.0 device plugs into a USB 3.0 port they will still work but only run at the speed of USB 2.0. 

    Thanks and Regards,

    Raymond Lin