PGA2311 Serial Protocol

Do I need to connect the PGA2311 ICs (CS-chip select) pin to a micro controller pin? Or can I connect that CS pin all the time low? I have only one PGA2311 IC & one micro controller.

The data sheet doesn’t mentioned when the “DATA IN” will latch to the PGA IC. At the end of the 16 bit binary code automatically the "DATA IN" will latch or after sending 16 bit binary code do I need to make “HIGH” the “CS” pin to lath this data?
 
This is my problem.