1- I do not want to use Dynamic Power Control in AD5757 and AD5755. Can I connect my 12 volt to Vboost or only min voltage is 15 volt.
2- In AD5755 can I do not connect AVss to -volt And the Vout_x is only 0-5 or 0-10 volt.
Yes if you are not using Vboost, this pin can be tied to 12V no problem.
We do not specify this as a uni-polar part. Is it not recommended to leave any supply as a "Do Not Connect".
You can connect Vss to GND however. For the particular outputs that you mention there will be a footroom issue, but outside of this it will be linear. We do not specify the part under these voltage conditions.
If you use the AD5755-1 which has the sense in buffer disconnected this footroom is far reduced in the order of 20-30mV.
Michael (PDA Applications)