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[SOLVED] what do i do about the unused pins of logic ICs?

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ful24

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hi everyone
i am building a small project that contains some logic ICs.
what should i do about the unused pins of those ICs?
the ICs are:
4027 dual J-K flip-flop (im only using 1 flip-flop)
LM339 quad voltage comparator (using 3 comparators)
4081 quad 2-input AND gate (using 2 gates)

i was thinking ground all the unused input/output pins. is it necessary? or does it matter?

regards
Jack
 

CMOS - ground them
LM339 - ground one, leave other open or tie to VCC (open will pull up).
 

Ground them means connect them straight to ground, right? all the input & output pins?

for LM339, what do you mean ground one? one input? doesnt matter inverting or non-inverting?

what about the output pin of LM339? just leave it there?

thanks for the qucik reply.
Jack
 

All outputs open circuit. The comparator inputs want to be at different
potentials to avoid chatter. It doesn't really matter which, bias current
is relatively constant. As long as the ground connection is close-in a
direct connection is fine. If it's a long "antenna" or there's a chance of
offset then a few-K resistor is OK, but probably unnecessary.
 
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    ful24

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all CMOS IC unused input pins should be grounded
all unused output pins should be kept open
4027---ground pins 9,10,11,12, and 13 if you use only one flip flop
4081---ground pins 8,9,12,13 if you use only two gates
LM339--ground pins 10,11 if you use only three comparators
 
just finished one of the exam, back to the project.
thanks for the clearification. helps a lot.
Jack
 

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