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TAS2521: TAS2521 TAS2505 Powerup sequence: IOVDD

Christopher Voss
Prodigy 120 points
Part Number: TAS2521


According to Section 3 of the Application Reference guides, and a post in this forum, IOVDD cannot rise before SPKVDD otherwise the LDO will not turn on. Is that true? I have two board supplies: SPKVDD at 5.0V and IOVDD at 3.3V. Now if the internal LDO supplies AVDD and DVDD from the SPKVDD, it seems very difficult for me to provide IOVDD between SPKVDD and the LDO outputs as required by the application reference guides. Is there some flexibility on when I apply IOVDD? Can it come after AVDD and DVDD? If not what is the recommended system design to ensure the right timing for IOVDD?

  • 0
    TI__Guru** 110815 points
    Hi Chris,

    You can power up first SPKVDD and then IOVDD. As long as IOVDD is not powered up before or at the same time as SKPVDD I think there should be no problem.

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 120 points

    I will just make sure that IOVDD comes up after or at the same time as SPKVDD. I won't worry about AVDD and DVDD being too early if they come from the internal LDO.

    A related follow-on question:

    If the I2C lines (SDA and SCL) are pulled up to a supply that is always on, will I accidentally power up IOVDD through the protection diodes?