This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Question about TUSB320 VBUS_DET

Other Parts Discussed in Thread: TUSB320, TUSB320HAI, TUSB320-HA-EVM

Dear, Sir.

I am having a  question about TUSB320 VBUS_DET.

6 page on the datasheet, external 900kOHM and typ. 3.3V thereshold

is defined. Also intrernal 95kOHM pull-down resistance is defined.

I suppose VBUS on USB TYPE-C will be 5V/500mA, 1.5A, 3A.

If the bias on VBUS_DET was the divided by resistors;

5V * 95kOHM/995kOHM = 0.48V

If true,  VBUS_DET voltage never across the threshold voltage.

Does it mean VBUS_DET was invalid unnder VBUS 5V condition?

Best Regards,

H. Sakai

  • Hello hideyuki,

    I am reviewing the spec with my team and I will provide a feedback ASAP.

    Regards,
    Diego.
  • Dear, Diego-san. 

    Sorry again. 

    This matter is getting important with my customer. 

    I am expecting your feedback. 

    Best Regards, 

    H. Sakai

  • Hello Hideyuki-san,

    I am sorry for the delay, the datasheet is under update process. We are including a note where we established that the threshold voltage is for direct VBUS, therefore the minimum detected value on the VBUS pin would be 2.95V * 95kOHM/995kOHM =0.28V

    Regards,
    Diego.
  • Dear, Diego-san. 

    Thank you so much for your valuable information. 

    And sorry to disturb your job, again and again. 

    Best Regards, 

    H. Sakai

  • Dear, Diego-san.

    My customer is making several questions about TUSB320HAI.

    Please give your advice.

    1. Vbus Maximum Voltage.

      VBUS_DET max voltage is defined as 4V.

      Does it mean real Vbus Maximum voltage will be 42V although

      recommended is max 28V?

    2. CC1/CC2 voltage under DFP-DFP connection.

      VDD=3.4 ~ 4.2V. VBUS = 5V. Rp(pull-up) is active inside of IC.

      I wonder CC1/CC2 is no problem because VDD+0.3V is defined on

      maximum ratings?

    3. VBUS_DET external pull-up.

      1Mohm is mounted on TUSB320-HA-EVM. It is making confusion on

      customer side.

      Please clarify real VBUS_DET threshold voltage.

    4. Hysteresis on VBUS_THR.

    Does VBUS_THR have hysteresis? If has, Please explain rising time &

    falling time to avoid miss-understanding.

    Best Regards,

    H. Sakai

  • Hello Sakai-san,


        First of all let me tell you that the 6V maximum voltage on the CC pins is also valid for the TUSBHAI & TUSBLAI.
     

        Now for VBUS_DET: 3.8V is the maximum VBUS_DET recommended value, which means that you can apply up to 4V to VBUS_DET without damage the pin, however we only warrant its proper functionality under the recommended operating conditions. This condition is also valid using the 1MOhm resistor between VBUS_DET & VBUS. I don't have the hysteresis value for the VBUS threshold, however the chip implements a debounce timer with a default value of 168ms (please see the register map, address 0x0A bits 7:6).


        CC pins: There is no issue since the actual maximum rating for the CC pins is 6V. (the datasheet is being updated).

    Regards,

    Diego.

  • Dear, Diego-san.

    Thank you for your valuable information.

    1. VBUS recommended voltage is 4 ~ 28V.
    I think it might be 4 ~ 6V considering all situation such as CC1/2 voltage under Rp-Rp connection.
    How do you think about it?

    2. RVBUS recommended value is 891kOHM ~ 909kOHM, 1MOHM is out of that.
    Do you have a plan to revise the datasheet?

    Best Regards,
    H. Sakai

  • Sakai-san,

    This is my feedback:

         1) You are correct, the voltage on the VBUS_DET terminal will be lower than 6V.

         2) It is under discussion.

    Regards,

    Diego.

  • Dear, Diego-san. 

    Thank you for your feedback. 

    I am expecting to brush up the datasheet definition contents to avoid the customer's

    misunderstanding & confusion, especially about BVUS recommended voltage & RBUS. 

    Best Regards, 

    H. Sakai

  • Dear, Diego-san. 

    Thank you for your support and sorry to disturb your job, again. 

    Before, we discussed about following topics. 

    1. VBUS recommended voltage is 4 ~ 28V. 
    I think it might be 4 ~ 6V considering all situation such as CC1/2 voltage under Rp-Rp connection. 
    How do you think about it?

    2. RVBUS recommended value is 891kOHM ~ 909kOHM, 1MOHM is out of that. 
    Do you have a plan to revise the datasheet?

    I have checked the latest DS on website, but VBUS & RVBUS definitions are no changed. 

    Please let me know the conclusion at your side. 

    Best Regards, 

    H. Sakai

  • Hello Sakai-san,

        VBUS is not rated from 4 to 6 because the RP conditions must be such that you have a 330uA at the CC pins and VBUS must be OFF before a successful CC detection on the DFP side, so no issue at all.

        The DS change disscusion in he RVBUS has been delayed due to the heavy work load, so far I can tell that 1MOhm is still OK to use as RVBUS.


    Regards,

    Diego.

  • Dear, Diego-san. 

    Thank you for your reply. 

    I would like to double-confirm about first topics. 

    Below is not normal operation, but it could be concerned. 

    Could you please explain why CC pin voltage never exceed 6V. 

    Best Regards, 

    H. Sakai

  • Hello Sakai-san,

        THis is not a valid connection. For this kind of implementation the TUSB320 must be in UFP mode, so the CC pin will see bout 2.8V. Please see the actual image taken from the TUSB320 online DS:

    Regards,

    Diego.

  • Dear, Diego-san. 

    Thank you for your reply. 

    I know the connection I sent is abnormal(miss-connection). 

    However, TUSB320 can set as DPF by setting of PORT pin. 

    User don't know which is UFP or DPF. 

    How to avoid this kind of miss-connection?

    Best Regards, 

    H. Sakai

  • Dear Sakai-san,

    The application you mentioned is a cable adapter or dongle, so in these cases, the UFP configuration must be fixed because it will be always connected to a legacy USB Type-A connector. No user interaction at all.

    Regards,

    Diego.

  • Dear, Diego-san. 

    Thank you for your teachings. 

    I suppose it couldn't avoid if both side were USB Type-C connector. 

    Change the discussion point ; 

    Page 8 on the datasheet, describes "TUSB320 devices do not suppoort any USB Type-C

    feature which requires USB power delivery communication". 

    I think it means that VBUS=5V, not to elevate to 12V or 20v. 

    The other side, Page 4, Max VBUS Recommendation Operating Condition = 28V. 

    I think it is contradicted & making confusion at customer side. 

    How do you think? 

    Best Regards, 

    H. Sakai

  • He Sakai-san,

        The TUSB320 does not support PD and thus, it is designed to work with 5V VBUS. However, it is capable to detect up to 28V via VBUS_DET, that's why we encourage the use of the 900K resistor. So it is not contradictory, the device is intended to work @ 5V but also supports up to 28V on VBUS to protect the device in such non compliant and undesired scenarios.

    Regards,

    Diego.

  • Dear, Diego-san.

    Thank you for your explanations.

    My customer have already finished the design & mass-production is closing, now.
    As the Japanese custom, we must provide "仕様書(specification)” including datasheet,
    reliability report, packing information.

    A guy in the section taking care such document is requiring to revise the datasheet
    description to avoid miss-understanding inside of his company.
    1) VBUS = 28V is defined on "Absolute Maximum Ratings".
    2) Delete VBUS=28V from "Recommendation Operating Conditions".

    Sorry to ask you about this kind of matter, but I am expecting to get your understanding
    and help at this time.

    Best Regards,
    H .Sakai
  • Sakai-san,


        The 28V is in recommended operating conditions because indeed is a condition fully supported by the device without issues. Meanwhile, the Maximum operating conditions are such that the device is could be damaged. The space between the recommended and Maximum is where the device is no longer guaranteed to work properly but still won't be physically damaged. Also, some customers use custom implementation where they use the TUSB320 with higher VBUS voltage (20V as far as I know), these applications are not USB compliant and won't be certified but some customers use the alternative anyway. The engineer who required the datasheet revision can address the Type-C specification as reference for the recommended operating conditions of the final product

    Regards,

    Diego.

  • Dear, Diego-san. 

    Thank you so much for your explanations. 

    Regarding "VBUS_DET" pin definition ;

    The rating is defined on Absolute Maximum Ratings portion. 

    The other side, "Figure1 : VBUS Detect and Debounce" page 7 & threshold

    definition page 6. These are defined based on VBUS voltage. 

    The guy is also requesting to unify such definition as ; 

    The threshold was defined by the voltage on "VBUS_DET" pin itself. 

    I would like to get your explanation against this request. 

    Best Regards, 

    H. Sakai

  • Sakai-san,

        This threshold is based on VBUS because it is the actual input to the system and a standard USB signal; it is defined in such way that when the customer uses the specified RVBUS (Now updated from 855K to 920K), the TUSB320 will detect a valid VBUS. This simplifies the testing because the customer only has to worry about VBUS and not extra variables.

    Regards,

    Diego.