Logic Gate Q

DamienH · 13-12-2006 02:17PM #1

Hey,

I've got an assignment to hand in for college, have to make some decoders and multiplexers. We have to plan all different combinations out and then choose the best on, respective of IC count and pin count aswell.

I already have a dual quad-input and gate in use. This IC has a spare gate and I'm wondering if there is any problem in using only 3 inputs on this remaining gate? I was thinking if I bridged one input onto the spare pin would it be the same.

I know I'm not the best at explaining things but hopefully someone understands

Ghost Train · 14-12-2006 11:02AM

you might have to discribe what you're asking a bit more clearly, do you have a diagram maybe. Are you wondering if the gates will work the way you're setting it out or are you asking is it an efficient way of using the available ic's & gates.

just read it again and you're saying AND gate, i read it as ic & gate lol

I suppose if you tie one of the four pins to logic 1 you can use the other three pins as a three pin AND gate, or bridge two of the input pins together and have this as one of the three input pins, which I think is what you were saying, sounds like a good way of doing it and using what you say is a spare gate.

dudara · 17-12-2006 12:56AM

eolhc is right, just connect the spare pin on the quad-input AND gate to logic 1. I personally wouldn't bridge it to one of the other inputs, as it might possibly cause the voltage to drop just below the trigger level.

Logic Gate Q

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