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PGA2310: Digital section always powered (& PGA2320)

Ivo Colleoni
Prodigy 10 points
Part Number: PGA2310

Hi all.

I'm wondering if leave the digital section of the PGA2310/2320 always connected and without power on the analog section can cause some strange effect on the output or can damage the device.

and.. I noticed that if I power on only the analog section I have about 3v on the Vd+ PIN. is that normal??

thanks

  • 0
    TI__Expert 6250 points

    Hi Ivo,

    In general it's not recommended (unless stated otherwise in the datasheet) to leave one supply floating. While doing so may not cause permanent damage to the device, device behavior in this case is completely undefined. For example, in a PGA, latches and registers to store gain settings may be powered off the digital supply, while the actual gain control elements are powered from the analog supply. In that example removing the digital supply would remove the control signals which set the analog gain.

    Leaving a supply floating can also cause junctions within the device to become forward-biased and conduct, which can also cause unintentional behavior (or latch-up in extreme cases). This may be what is causing the 3V output on the Vd+ pin when no digital supply is present. Without any bias on the digital section, there's a leakage path from the analog supply causing the digital supply to float to that 3V level.