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TUSB8020B: post driver current or slew rate control register

Shu-Cheng LIN
Guru 11785 points

Part Number: TUSB8020B

Hi Sirs,

Sorry to bother you.

Does TUSB8020 have any post driver current or slew rate control register can setting?

Thanks!!

  • 0
    TI__Guru 60870 points
    Hello Shu-Cheng,

    There is no way to adjust the USB 3.0 signals, but the USB 2.0 signals can be adjusted by changing the resistor on USB_R1. A lower value (~8K) increases the USB 2.0 signal strength.

    Regards,
    JMMN
  • 0 in reply to JMMN
    Guru 11785 points

    Hi Sirs,

    Thanks for your reply.

    USB2.0 signal has been verified. 

    We found the eye is too large on 1port(USB_DP/DM_DN1).

    Looks need to select DC level, right?

    As discussed before, looks we could change resistor on USB_R1?

    So base on our eye pattern, could you help share the suggest USB_R1 value for us?

    By the way, that won't effect U3 signal if we change USB_R1, right?

    Failed port:

    Passed port:

  • 0 in reply to Shu-Cheng LIN
    TI__Guru 60870 points
    Hi Shu-Cheng,

    USB-R1 resistor only impacts USB 2.0 performance. I would recommend changing the value to 10K for this application.

    Can you confirm the test setup? If you are using the USB-IF test boards and a LeCroy scope, you many need to adjust the attenuation of the probe input.

    Regards,
    JMMN