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TUSB320LAI: Why the VDD needs to larger than 3.5V for Advertise 3A current?

GW
Intellectual 2400 points
Part Number: TUSB320LAI
Other Parts Discussed in Thread: TUSB320,

Tool/software:

Hi, Team

My customer use our TUSB320 in one of the project, the VDD in their design is 3.3V. 

they prefer to Advertise 3A in the Type-C port. 

But from our datasheet, it shows "VDD must be 3.5 V or greater to advertise 3 A current." 

Could u help to confirm this? Why VDD must >3.5V for advertise 3 A current?

If we use 3.3V VDD, does it mean that we can only advertise max 1.5A current?

Thanks

G.W

  • +1
    TI__Genius 17516 points

    Hi GW,

    GW said:
    Why VDD must >3.5V for advertise 3 A current?

    This is to ensure the proper functioning of TUSB320LAI when it is advertising 3A mode.


    GW said:
    If we use 3.3V VDD, does it mean that we can only advertise max 1.5A current?

    If you use 3.3V VDD, then the device can only advertise max 1.5A current. 

    Let me know if you have other questions.
    Best,
    J

  • +1
    TI__Mastermind 32045 points

    Hi GW,

    VDD must be 3.5V or greater so that our part can advertise the correct pullup on the CC lines for 3A current mode. The current mode in CC negotiation is determined by the strength of pullup that the DFP presents on the CC1/CC2 lines. Simply put, a stronger pullup = higher current mode. In order to get the 3A pullup from our device, VDD must be 3.5V or greater.

    GW said:
    If we use 3.3V VDD, does it mean that we can only advertise max 1.5A current?

    Yes this is correct. I do not recommend using the 3A current mode setting when VDD is 3.3V. Doing so could interfere with the CC negotiation or negotiate the wrong current mode.

    Let me know if you have any questions.

    Best,

    Shane