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TUSB4020BI: Operating problems of TI's TUSB4020BI

Shlomi Yehezkia
Mastermind 6150 points
Part Number: TUSB4020BI

Hi Team,SCHEMATIC1 015 USER Inerface,.pdfSCHEMATIC1 016 BATTERY CHARGE.pdf

We are having a repeating problem with the USB devices connected to the USB hub:

Some boards work Ok

In Some board the USB connected to DN1 port is not responding

In Some board the USB connected to DN2 port is not responding

 

We have replaced the TUSB420BI device between working board and a fault board, the problem remains with the TUSB420BI device (ie,after the replacement, the fault board is now working and the working board stopped working.)

 

Attached please find the block diagram:

 

Attached please find the schematic.

USB_VDD=1.02v

USB_VDD_33=3.06v

 

Please advise.

Thanks,

Shlomi

Block Diagram.docx

  • 0
    TI__Guru* 76130 points
    Hello,
    The schematic looks correct on the Hub portion.
    What is the voltage at VDD11 and VDD33 in a working board?
    What is the failing rate?
    Can you elaborate more on the USB_switch implementation? what is the purpose? Can they by-pass the switches to see if the problem remains?
    Regards
  • 0 in reply to Elias Villegas M.
    Mastermind 6150 points

    Hi,

    VDD11 – 1.1V

    VDD33 – 3.05V

    Failing rate – about 15% of 200 boards.

    -          10% fail on USB MUX

    -          5% fail on USB HUB.

     

    We have two failure scenarios:

    1.       No USB at all.

    a.       We see it as USB Hub failure.

    b.      When replacing the USB Hub device – problem solved.

    2.       No USB only to A9 Master or only to A9 Slave.

    a.       We see it as USB MUX failure.

    b.      When replacing the USB MUX device (Master or slave, depend on failure) – problem solved.

     

    We never see failure in the USB switch.

    We use the USB switch to help the Battery charger distinguish between USB Host and USB charger connection (Using PSEL to limit 0.5A charging current when USB host is recognized on the USB switch).

    Thanks,

    Shlomi

    B.D.docx

  • 0 in reply to Shlomi Yehezkia
    TI__Guru* 76130 points
    Hello,
    If the failing units fail 100% of time then I recommend you to start a Quality Return process, if the failing units are failing randomly then I suggest taking some X-ray of a failing board to see the thermal pad soldering.
    Regards