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TUSB2077A: Errata

user4997485
Prodigy 20 points
Part Number: TUSB2077A

TUSB2077A User's Guide "SLLU190–December 2013"

The EVM schematic is shown in "Figure 6. TUSB2077A EVM Schematics".

Q1 in this circuit diagram pulls up DP when power is turned on.

Can this Q1 be considered as a countermeasure for the following errata?

TUSB2077A Errata “SLLZ052–October 2006” 1.2Discription “TI has no planned fix in the pipeline, but wants users to be aware of this issue, which can easily be avoided by guaranteeing that DP be asserted high before DM.”

  • 0
    TI__Guru*** 146535 points

    Hi

        for Q1: the EVM schematic can not guarantee DP pullup first of the downstream port device when power is turned on. the downstream port device need to make sure  DP be asserted high before DM when connected to TUSB2077.

        It  can be resolved by performing a CLEAR_PORT_FEATURE(PORT_ENABLE) followed by a RESET_PORT in the software driver.

    Regards

    Brian

  • 0
    Prodigy 20 points

    Hi　Brian

    Please tell me a little more.

    1.Does this errata mean that measures need to be taken on the target device side connected to the TUSB2077A?

    2. Does "executing RESET_PORT in the software driver" refer to the target device's software driver?

    3. Due to various reasons, the software driver cannot be modified. In that case, can I solve this problem by adding a pull-up circuit similar to Q1 to the target device?

    4. If 3. above does not work, please let me know how to solve the problem using hardware.

    Regards,Takayuki

  • 0 in reply to user4997485
    TI__Guru*** 146535 points

    Hi Takayuki:

       Here is my reply for your questiosn:

    1: yes,  this errata mean that measures need to be taken on the target device side connected to the TUSB2077A

    2: "executing RESET_PORT in the software driver" refer to the host firmware.

    3:  if you can make sure DP  is  asserted high before DM , then it should work as well. Is your device always connected to TUSB2077A  for your application?

    4: Let me discuss with our system engineer and get back to you.

    Regards

    Brian

  • 0 in reply to Brian Zhou
    TI__Guru*** 146535 points

    Hi Takayuki:;

          Sorry for the delay, After discussing with team, we don't think there is solution with hardware only.

    Regards

    Brian

  • 0 in reply to Brian Zhou
    Prodigy 20 points

    Hi　Brian

    Thank you for your consideration, I understand.

    Takayuki