AD970x - Internal Reference at Power Up

Regarding the note in the AD970x datasheet:

"The internal 1.0 V band gap reference may on occasion power up in a state that leaves the DAC output nonfunctional. To clear this state, power up again, and check that the voltage on the REFIO pin is within the reference output specifications..."

  1. Is this outcome (DAC output nonfunctional) possible when using an external reference?
    1. Does it make a difference if the internal reference is powered up/down via reg 0x00 bit 0? (band gap on/off)
  2. "Power up again" - is toggling SLEEP/CSb sufficient?
    1. Or toggling reg 0x00 bit 0? (band gap on/off)
    2. Or register 0x00 bit 3? (band gap and output current driver on/off)

This issue is addressed in a couple of older threads with no public resolution besides "use a different part":

ad9707-boot-up-initialization-issue

ad9704---powers-up-in-a-state-that-leaves-the-dac-output-nonfunctional

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