Translation - Japanese: NCピンとDNUピンについて - Community Translated (JA)
What is NC and DNU pin and what should I do with them, please suggest?
NC stands for No Connect which means that the pin is not internally connected to the die. So it can be either left floating or tied to GND or tied to VCC. DNU stands for Do Not Use. DNU pins might be used for test mode entry and hence these pins have to be left unconnected/floating.