|IC Number||IC Name|
|74LS20||Dual 4-Input NAND Gates|
NAND gate is a digital circuit that has two or more inputs and produces an output, which is the inversion of logical AND of all those inputs.
Logic NAND Gates are available using digital circuits to produce the desired logical function and is given a symbol whose shape is that of a standard AND gate with a circle, sometimes called an "inversion bubble" at its output to represent the NOT gate symbol with the logical operation of the NAND gate.
As with the AND function seen previously, the NAND function can also have any number of individual inputs and commercial available NAND Gate IC's are available in standard 2, 3, or 4 input types. If additional inputs are required, then the standard NAND gates can be cascaded together to provide more inputs.
Boolean Expression Y = (A.B.C.D)'
"If either A or B or C or D are NOT true, then Y is true"
NAND gate operation is same as that of AND gate followed by an inverter. That's why the NAND gate symbol is represented like that.