Leave unused CMOS outputs open.
However, since the open circuit is not terminated and has total reflection, if an EMI problem occurs, connect a capacitor of several tens of pF and a resistor of several tens of ohms in series to terminate the circuit alternately.
The following documents also contain related information:
CMOS Logic ICs Selection Guide
Basics of Bus Switches
CMOS Logic ICs Usage Considerations
Basics of CMOS Logic ICs
CMOS Logic Ics Standard series
CMOS Logic Ics TC74VCX/LCX Series
CMOS Logic Ics TC74HC/HCT Series
CMOS Logic Ics TC74VHC/VHCT/VHC9/VHCV Series
CMOS Logic Ics TC74AC/ACT Series
Glossary of CMOS Logic ICs
Is it OK to leave the unused inputs of general-purpose CMOS logic ICs open?
If multiple outputs from a general-purpose CMOS logic IC come into conflict, is the IC adversely affected?
Is it OK to leave the bus terminal (input/output) pin of a bidirectional bus buffer open when it is floating?
Tell me about the handling of the unused input terminal of bus switches and analog switches.
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