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