 Negated AND gate

This article is about NAND in the sense of an electronic logic gate. For NAND in the purely logical sense, see Sheffer stroke. For other uses of NAND or Nand, see Nand (disambiguation).
INPUT
A BOUTPUT
A NAND B0 0 1 0 1 1 1 0 1 1 1 0 The Negated AND, NO AND or NAND gate is the opposite of the digital AND gate, and behaves in a manner that corresponds to the opposite of AND gate, as shown in the truth table on the left. A LOW output results only if both the inputs to the gate are HIGH. If one or both inputs are LOW, a HIGH output results.
The NAND gate is significant because any boolean function can be implemented by using a combination of NAND gates. This property is called functional completeness.
Digital systems employing certain logic circuits take advantage of NAND's functional completeness. In complicated logical expressions, normally written in terms of other logic functions such as AND, OR, and NOT, writing these in terms of NAND saves on cost, because implementing such circuits using NAND gate yields a more compact result than the alternatives.
NAND gates can also be made with more than two inputs, yielding an output of LOW if all of the inputs are HIGH, and an output of HIGH if any of the inputs is LOW. These kinds of gates therefore operate as nary operators instead of a simple binary operator. Algebraically, these can be expressed as the function NAND(a, b, ..., n), which is logically equivalent to NOT(a AND b AND ... AND n).
Contents
Symbols
There are three symbols for NAND gates: the 'distinctive' (MIL/ANSI) symbol and the 'rectangular' IEC symbol, as well as a deprecated DIN symbol sometimes found on old schematics. For more information see logic gate symbols.
MIL/ANSI Symbol' IEC Symbol DIN Symbol Hardware description and pinout
NAND gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs.
CMOS version
The standard, 4000 series, CMOS IC is the 4011, which includes four independent, twoinput, NAND gates.
Availability
These devices are available from most semiconductor manufacturers such as Fairchild Semiconductor, Philips or Texas Instruments. These are usually available in both throughhole DIL and SOIC format. Datasheets are readily available in most datasheet databases.
The standard 2, 3, 4 and 8input NAND gates are available:
 CMOS
 4011: Quad 2input NAND gate
 4023: Triple 3input NAND gate
 4012: Dual 4input NAND gate
 4068: Mono 8input NAND gate
 TTL
 7400: Quad 2input NAND gate
 7410: Triple 3input NAND gate
 7420: Dual 4input NAND gate
 7430: Mono 8input NAND gate
Implementations
The NAND gate has the property of functional completeness. That is, any other logic function (AND, OR, etc.) can be implemented using only NAND gates. An entire processor can be created using NAND gates alone. In TTL ICs using multipleemitter transistors, it also requires fewer transistors than any other gate.
See also
 AND gate
 OR gate
 NOT gate
 NOR gate
 XOR gate
 Boolean algebra (logic)
 Logic gates
 NAND logic
 Digital electronics
External links
Categories: Logic gates
 CMOS
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