• Resolved

Question about TUSB320 VBUS_DET

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.
  • In reply to Diego Cortes:

    Dear, Diego-san. 

    Sorry again. 

    This matter is getting important with my customer. 

    I am expecting your feedback. 

    Best Regards, 

    H. Sakai

  • In reply to hideyuki 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.
  • In reply to Diego Cortes:

    Dear, Diego-san. 

    Thank you so much for your valuable information. 

    And sorry to disturb your job, again and again. 

    Best Regards, 

    H. Sakai

  • In reply to hideyuki 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

  • In reply to hideyuki 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.

  • In reply to Diego Cortes:

    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

  • In reply to hideyuki 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.

  • In reply to Diego Cortes:

    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

  • In reply to hideyuki 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