In my case, I plan to use the AD5412 with two independent power supplies :
- A +3,3V digital supply coming from one source (source #1)
- A +/-15V dual supplies coming from another source (source #2)
Both sources are independent. Here after the identified board states according to sources behaviour:
- State #1: source #1 OFF, source #2 OFF:
- State #2 : source #1 OFF, source #2 ON
- State #3 : source #1 ON, source #2 OFF
- State #4: source #1 ON, source #2 ON
At board power up (State #1 -> State #4), state #2 or state #3 can be a transitional state during unknown duration. To prevent any wrong DAC powering-up, the master will set the CLEAR pin to high level as the board goes to state #4. This preconisation is well explained in the datasheet.
My question is about the power-down event. Indeed, a external event can force the board to go from state #4 to state #2 or #3 for an unknown duration. In any case, the DAC output shall be deactivate (Unipolar Vout = 0V, Iout left open).
Could you confirm that loss of one supply would force the DAC output in this safe state ? I’m pretty sure that loss of Analog supply would force the DAC in safe state. However, I have few doubt about the DAC behaviour if only digital supply would go down: since the master could force a high level to CLEAR pin nor drive SPI, DAC output could be frozen in its previous configuration output (Vout > 0V or Iout > 0 mA depending on the DAC configuration) ?
Thank you in advance for your feedback, I hope I would have been clear enough to describe my issue.