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TPA3220: Fault and OTW Pull Up Voltage

Tyler Turcotte
Prodigy 20 points
Part Number: TPA3220

Good Day,

I have a TI TPA3220 on a custom board along with a TPA3220 Micro Eval kit. The issue that I have been seeing is that in the default pull up state, the value is not the 3.3V as stated but actually 3.9V.  It seems as though others may have been experiencing a similar problem on your forum.  Unfortunately our inputs to monitor these two pins rely on the 3.3V interface.  Besides that it seems like the custom board and the eval kit perform exactly as expected.  Is there something here that I am missing or is there an issue with the datasheet currently?

Thanks,

Tyler

  • 0
    TI__Mastermind 39590 points

    Hi Tyler

        There's something we need to check.

           1. What device been connected to this two pins on our customer's board? Do they have additional pull up?

           2. Does thie phenomenon happens to many boards or only one of them?

           3. What equipment do you use to test this voltage? Can you use mutimeter to test it?

  • 0 in reply to Shadow He
    Prodigy 20 points

    Shadow,

    1.There is nothing additional connected to these two pins.

    2. This phenomenon happens to all the boards.

    3. I've used both an oscilloscope and a multimeter to test the voltage level.

  • 0 in reply to Tyler Turcotte
    TI__Genius 9870 points

    Hello Tyler,

    You are correct, the table here is not fully correct. In your applicaiton, when connected with 3.3V MCU, an resistor divider should be used to attenuate the voltage down to 3.3V level.

    Dylan

  • 0 in reply to Dylan Yao
    Prodigy 20 points

    Is there a new derived value that I should follow to set the resistor divider?  Will it be 3.9V all the time and what is the tolerance? I want to ensure that it is within tolerance of the FPGA that is reading the value.

    Are there any plans to update this table?

  • 0 in reply to Tyler Turcotte
    TI__Genius 9870 points

    Tyler,

    I don't have a good answer about how much pull up resistor is internally used. So can't provide the resistor divider to you now.  I am checking with design about this, hopefully will feedback you tomorrow.

    Dylan

  • 0 in reply to Dylan Yao
    Prodigy 20 points

    Thanks Dylan for the feedback. I also measured my micro Eval Boards from TI for the TPA3220.  They read 5V rather than 3.9V.  This is slightly concerning as this means it is not a standard and may depend on the layout as maybe the pull up resistor isn't strong enough?

  • 0 in reply to Tyler Turcotte
    TI__Genius 9870 points

    Tyler,

    Device internal is pulled up to 5V by a resistor.  There is possibility the 5V could have some variation, but varies to 3.9V is really big change.  So i am wondering if there is any external load on the pin, which result in voltage decrease to 3.9V. Did you check if nothing connected on that pin in your micro board?

    Unluckly, i didn't get an answer from design team. I am still asking.