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TUSB321: TUSB321 DIR output does not toggle when the plugged USB Type C device orientation is changed

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Replies: 12

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Part Number: TUSB321

In one our design, we are using TUSB321 and HDSS3212 to design a DFP  USB Type C port with a standard USB 3.0 port as the source. Our schematic is very similar as Figure 4 showed in TUSB321 datasheet (on  Page 13). When we test the design, we the DIR output from TUSB321 is always High (about 3.3V) when the plugged USB3..0 device orientation is changed. And we also found that with one plugged orientation the plugged device is recognised as Supper Speed device. On another orientation the same device is recognised as High speed device. Could you please what could I do to debug this issue.

Thanks,

De

      

  • Hi De,

    Probe the VBUS and CC pins. VBUS must be disabled when CC lines are high, otherwise orientation detection will not work. VBUS should only be high after one of the CC pins drops to a valid detection voltage for 100-200ms.
    Regards
    Brian
  • In reply to Brian Quach:

    Hi Brian,

    Thank you for the quick response.

    This USB Type C port is designed according to a TI Evaluation board, USB-CTM-MINIDK-EVM, The TI Reference schematics is TIDA-01243_SCHEMATIC.DSN. We are using page PAGE09_PORT2_USBC_2 of the reference schematics as the reference. Please see the attached schematics to see if some thing is wrong with our schematics. From the attached schematics you could see that, we have not control on the VBUS. So along as power up, the VBUS is always enable (+5V). Do you think this will cause the the problem for detecting plugged device orientation? What should the correct connection?

    Thanks,

    De

  • In reply to De De Li:

    Sorry, I could not attach the schematics file. How could I attach a file? I cold send you the pdf schematics if you give me email address.
  • In reply to De De Li:

    Hi, VBUS *cannot* be always enabled.  That will definitely cause your DIR issue and is not compliant to the Type-C spec.  I took a look at the TIDA schematic.  VBUS is controlled by the TPS25910.  The enable pin to that part is controlled by TUSB321 ID pin.

    Regards,

    Brian

  • In reply to Brian Quach:

    Yes. You are right. I found that issue and modifying the board to connect the EN# pin to the ID pin to see if the problem could be fixed.

  • In reply to De De Li:

    Hi Brian,

    After I connected TUSB321 ID pin to TPS25910 EN# (there is a 200k resistor pull-up resistor as the TIDA schematics to pull net 321_ID# to +5V), I found the net 321_ID# (see the schematics you post above) is always high. This means that U51 is never enabled. So this USB port will not work. Do you have any idea why TUSB321 does not enable the VBUS?
  • In reply to De De Li:

    Hi, the TUSB321 will pull ID pin low after a single CC pin drops to a valid detection voltage for 100-200ms. PORT pin should be pulled-up to VDD.
  • In reply to Brian Quach:

    The reference design has been built and tested so you should check to see if you have some other difference with your design.
  • In reply to Brian Quach:

    Hi Brian,

    I have compared the schematics with the reference design, no difference were found. It is also confirmed that PORT is pulled up to VDD. On the un-powered state, I checked the resistance between CC1 to GND and CC2 pin to GND when I flipped the plugged orientation of the USB Type C device, I found that on one orientation the resistance for CC1 pin is about 4K and resistance for CC2 very high. On another orientation, the resistance for CC1 is very high and the resistance for CC2 pin are about 4K. This means that the inputs to CC1 and CC2 pins are correct. However, I always found ID pin is always high and DIR pin never flip. All these indicate TUSB321 does not work as it expected. I still do not know why. I'm going to check the waveforms according to Figure 5. Application Curve for DFP Mode on TUSB321 datasheet. According to Figure 5, CC1 and CC2 should be high (pulled to high by TUSB321) before attaching a USB Type C device to the port. Is that correct?

    Do you have any other suggestions to debug this issue? Or do you have any suggestions to prove TUSB321 is working? I suspect the TUSB321 on the board is not working for some reason.

    Thanks,

    De

  • In reply to De De Li:

    Hi De,
    Yes, with no device attached, you should see that ID pin is high, CC1/CC2 are high, and VBUS should be low.
    After attaching the device, you should see one of the CC pins has a lower voltage (see Type-C spec for valid range). ID should be low and VBUS should be high.

    If you have verified everything is correct and it still is not working properly, you can try replacing the TUSB321 device.

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