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PCM1789 - Running with no VCC?

Fritz Capell
Prodigy 30 points
Other Parts Discussed in Thread: PCM1789

I have an application involving a PCM1789, wherein the analog supply is not always available. As presently designed, the product can run for an indefinite period period of time with the digital supplies (VDD) at 3.3V, but the analog supply floating. It appears to float to about +2V due to slight leakage from the PCM1789, held by a large bypass capacitor on that supply.

I am wondering if this is an acceptable operating condition for the PCM1789? The datasheet specifies that it doesn't matter in which order the supplies come up, which implies that it is ok at least for a short time, but I'm not sure this should be construed to mean that it can operate that way indefinitely.

  • 0
    TI__Mastermind 27900 points
    Hi Fritz,

    I agree that this situation does not violate any limitations in the data sheet, I feel that this is a scenario that we have not fully tested, so I cannot fully recommend this type of operation, but I also do not have proof that this will cause damage. I will comment that leakage from the analog supply due to the digital supply being on is concerning.

    Justin