AM5728: USB1_DP signal issue

Prodigy 30 points

Replies: 5

Views: 76

Part Number: AM5728

I am evaluating the board for SITARA's USB 2.0 port.
In our USB2.0 circuit configuratio SITARA acts as a host.
We turned on the board without connecting a USB device to the “USB1 port”.
And the waveform from “USB1_DP” to VBUS release was acquired.
Only on the USB1_DP side, a phenomenon of rising about 2.5 [V] occurred.(See waveform below)
    
This phenomenon occurred when power was supplied to the “VDDA33V_USB1” pin of SITARA from the power supply control IC (TPS6590377ZWST).
In addition, SITARA has confirmed that it is in a power-on reset state.
【QUESTION1】
   What is the reason why only USB1_DP is excited about 2.5 [V]?
   Is it affected by HI-Z? Or is the internal pull-up affected?
  Does this always occur when using SITARA on the host? . If there is a way to avoid it, please let me know.
【QUESTION2】
   After canceling the power-on reset of SITARA,The USB_DP signal has changed to about 0 [V].
   Is that because the USB 2.0 standard 15KΩ pull-down has been enabled?

5 Replies

  • Hi,

    Your query has been assigned to a TI engineer. Please note that feedback may be delayed due to holidays in the USA.

    Please post the waveform. It's not visible on your original post.

     

    Best Regards
    Biser
  • In reply to Biser Gatchev-XID:

    Hallo,
    A waveform is attached below.
    >Only on the USB1_DP side, a phenomenon of rising about 2.5 [V] occurred.(See waveform below)
    >This phenomenon occurred when power was supplied to the “VDDA33V_USB1” pin of SITARA from the power supply control >IC (TPS6590377ZWST).
    >In addition, SITARA has confirmed that it is in a power-on reset state.
     A waveform is attached below.
     
  • In reply to user6236094:

    Hi,

    I have not seen this reported previously. Which board did you observe this on?

  • In reply to -DK-:

    HI,
    Thank you for your answer.
    I will answer below.
    This is a self-made board created by our company.
  • In reply to user6236094:

    Hi,

    I've tried to reproduce this issue in the lab using our AM572x IDK EVM, but I am unable to see the issue. My suspicion is that your board has a sequencing issue that is not present on our EVM. I am not a power expert, so I'll need to pull in a coworker for this. Please allow a day or so for them to respond.