Good morning. My question is very simple: I would like to know where the unused pins (in case of a single DDS AD9951 design) should be connected?
- pin 10 CRYSTAL OUT=unused since CLKMODESELECT (pin 11) is low in my case;
- pin 44 SYNC_IN=unused since I have only one DDS;
- pin 45 SYNC_CLK=unused since I have only one DDS.
To keep noise from coupling in on those pins, is it better to place a capcitor (=0.1uF) to AGND or it does not matter and they could be left floating? In fact, I was unable to find any hint on the data sheet. Thanks a lot.