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TUSB212: The host can't recognize external notebook with TUSB212

Gabriel Xu
Intellectual 2145 points
Part Number: TUSB212

Hi team

My customer is using TUSB212 in a new TV project.

With TUSB212 it could normally work and recognize notebook from many different vendors except Razer's notebook.

I capture the K/J signal waveform and found that when the USB host is handshaking with the notebook. The D+ high-level voltage is 560mV and different from D- high-level voltage 460mV. The EQ gain is level 0 and DC boost is 80mV.

Could you give me some advice about how to fix this? Thanks in advance.

  • 0
    TI__Guru**** 175971 points

    Gabriel

    Have you tried low or mid DC boost?

    Thanks

    David

  • 0
    TI__Guru 64326 points

    Hi,

    The USB 2.0 handshake is tripping the disconnect threshold by having a differential amplitude greater than 525 mV. Please try low DC Boost of TUSB212. 

  • 0 in reply to Malik Barton57
    TI__Intellectual 2145 points

    Hi teams

    I onsite debug this case today and I collected some information for you to further narrow down the root case.

    First of all the customer system block diagram is shown below:

    1. Between the USB hub IC there are two USB switch device that adds 6~8ohm resistance in data line.
    2. This USB2.0 re-driver is work with a full function Type-C interface in TV side.
    3. Customer oringinal boost lever is 80mV, I have tried 40mV but still not work in ThinkPad notebool and severals other brands notebook
    4. If add a Type-C to Type-A plug and connect the notebook through Type-A port the connection is success in ThinkPad.

    What I have checked:

    1. USB high-speed handshake is success in the begining even in the ThinkPad. (Shown in Picture.2) Idle states, 0.8V K/J chrisp and 0.4V K/J chrisp is obersvered. But the communication will stop.
    2. After several data package TUSB212 exit high speed mode and the HS Flag is turn from high to low level. (The Pink waveform)
    3. Before the device stop communication and exit high speed mode, the differential pair lever is 800mV with 80mV DC Boost Gain and 640mV with 40mV DC boost Gain. But both the MacBook/Mate Book(Which could connect normally) and ThinkPad the voltage level is the same. I understood that 625mV differential voltage may lead to communication stop but i don't know why it work in MacBook and MateBook.

    I also want to konw if the differtial voltage level is too high and the boost gain is already in minimum configuration 40mV, how to fix such issue?

    As two D+ line could simplely short together in Type-C interface or otherwise we could leverage a MUX to controll the data line.

    Are two D+ line short together in note book side will lead to this issue?

  • 0 in reply to Gabriel Xu
    TI__Guru 64326 points

    Issue has been taken to internal forum. Closing ticket.