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TUSB321: TUSB321 does not work as expected

zhongfei zhao
Prodigy 141 points

Part Number: TUSB321

Hi TI team,

I am using the TUSB321RWBR as a CC controller. The circuit diagram is shown below. When I connect an external hub, I find that the DIR pin outputs a high level, which is not the expected low level. Then I removed the hub and connected the USBC_CC1 signal on the board to ground through a 5.1k resistor (to simulate a Type-C interface connected to a device). At this point, the DIR pin still outputs a high level. Next, I only connected USBC_CC1 to 5V through a 22k resistor and also shorted USBC2_VBUS to 5V (to simulate a Type-C interface connected to a host). The DIR pin still outputs a high level. May I ask what could be causing the abnormal operation of the TUSB321RWBR?

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  • +1
    TI__Guru 64426 points

    Hi,

    Can you share a pdf of the schematic?

    Can you try the following:

    1) plug in the USB Type-C cable, measure the DIR pin

    2) flip the USB Type-C cable at the USB Type-C connector on this board, measure the DIR pin

    3) Flip the USB Type-C cable at the downstream device, measure the DIR pin

    4) Flip the USB Type-C cable at the USB Type-C connector on this board, measure the DIR pin

  • 0 in reply to Vishesh Pithadiya
    Prodigy 141 points

    Hi Vishesh

    I used a USB Type‑C hub connected to J16. The test results are as follows.

    1) plug in the USB Type-C cable, measure the DIR pin ==>>the voltage of DIR pin is 3.2V

    2) flip the USB Type-C cable at the USB Type-C connector on this board, measure the DIR pin ==>>the voltage of DIR pin is 3.2V

    3) Flip the USB Type-C cable at the downstream device, measure the DIR pin ==>> Because a USB Type‑C hub is used, can't flip the USB Type-C cable at the downstream device.

  • 0 in reply to zhongfei zhao
    TI__Guru 64426 points

    Do we see any functional issues enumerating the downstream device?

    Its possible that if this is a fixed connection that the downstream device is always connected to CC1/ CC2, and this is why we do not see DIR update. 

  • +1 in reply to Vishesh Pithadiya
    Prodigy 141 points

    Hi Vishesh,

    The issue has been identified: it was due to a soldering problem – the assembly house placed the chip with pin 1 oriented incorrectly. After replacing the component and re-soldering it properly, the functionality is now back to normal. Thank you for your support.