Unused inputs must be terminated to either V_CC or ground. These can be directly terminated if the input is completely unused, or they can be connected with a pull-up or pull-down resistor if the input is to be used sometimes, but not always. A pull-up resistor is used for a default state of HIGH, and a pull-down resistor is used for a default state of LOW. The resistor size is limited by drive current of the controller, leakage current into the CD74HCT10, as specified in the GUID-404108F1-8DE3-4781-900D-294BAE4314A4.html#GUID-404108F1-8DE3-4781-900D-294BAE4314A4, and the desired input transition rate. A 10-kΩ resistor value is often used due to these factors.

Refer to the GUID-14F6719C-F191-46A5-B3D1-BFB02A5D6C21.html#GUID-14F6719C-F191-46A5-B3D1-BFB02A5D6C21 for additional information regarding the inputs for this device.