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[FAQ] TUSB4041I: How to configure USB 2 driver strength of TI USB 2 Hubs?

Part Number: TUSB4041I
Other Parts Discussed in Thread: TUSB8042A

I am using TUSB4041I and I would like to change the driver strength of my USB 2 Hub to help with signal integrity issues and USB 2 enumeration. Do TI USB Hubs have this capability? 

  • When using TUSB4041 or any TI USB Hub (i.e. TUSB8042A, etc) the USB 2 High-speed driver can be configured to help increase drive strength and combat USB 2 signal integrity issues. The TI USB Hubs provide an external pin named USB_R1 to adjust the USB 2.0 High-speed driver drive strength.

    Adjusting this resistor can also be useful when there are some issues with USB 2 enumeration to downstream devices with some devices. Increasing USB 2.0 High-speed drive strength can be useful when implementing a USB Hub with long transmission media with a high DC loss and helping to improve the USB 2.0 eye height. Decreasing USB 2.0 High-speed drive strength can be useful when the High speed disconnect threshold is violated during High-speed communication. 

    Adjusting the USB_R1 pull down resistor only affects the downstream port USB 2.0 High-speed transmitters and does not effect the USB 3.x SuperSpeed transmitters.Changing the resistor on this pin does not impact the upstream facing port.

    For more information on the allowable range of the USB_R1 pin pull down resistor, please see the TI USB Hubs: Adjusting USB_R1 document on