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TUSB320LAI: I2C Pulled Up to VDD=5V

Nicholas Kimball
Prodigy 20 points
Part Number: TUSB320LAI

Tool/software:

Hello,

Can the SDA/SCL pins of the TUSB320LAI be pulled up to VDD if VDD = 5V? The Abs Max Ratings shows SDA & SCL have the same ratings as the other IO pins (PORT, ADRR, ID, EN_N, INT_N/OUT3). However, in the Electrical Characteristics it shows the  VDD_I2C supply range as 1.65 - 3.6 V. From a logic level perspective, it seems fine. However, I want to confirm it will not lead to any reliability issues.

We are powering the TUSB320LAI with VDD=5V and our I2C pullup voltage is 1.8V. However, the 1.8V will come up before the 5V rail due to our system's power architecture. Therefore, we plan to pull up the I2C bus on the TUSB320LAI side to VDD and use a level shifter to shift down to 1.8V to avoid backpowering the device. Can you please confirm this will not cause any issues on the TUSB320LAI side?

Thanks!

  • 0
    TI__Mastermind 38755 points

    Hi Nicholas,

    So is the concern here that the I2C lines will be pulled up to VDD(5V) temporarily before being shifted down to 1.8V? Or are you just concerned about using the 5V rail to level shift the 5V down to 1.8V?

    I believe that this application would work. If these pins are exposed to 5V temporarily before being shifted down to 1.8V, I believe it should be able to handle this voltage for at least a small amount of time.

    Please let me know if you have any questions or need some more clarification.

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 20 points

    Essentially, I just need to know if the TUSB320LAI can tolerate 5V signals on its SDA/OUT1 and SCL/OUT2 pins if VDD=5V.

  • +1 in reply to Nicholas Kimball
    TI__Mastermind 38755 points

    Hi Nicholas,

    Got it. Yes, the TUSB320LAI should be able to tolerate 5V. Just make sure that VDD on the device is powered beforehand if possible to prevent backpowering.

    Thanks,

    Ryan