TexasInstruments 7400 chip, view and element placement

digital electronics Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. This is in contrast to analog electronics and analog signals. Digital electronic circuits are usual ...

, a NAND gate (NOT-AND) is a

logic gate A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic ga ...

which produces an output which is false only if all its inputs are true; thus its output is complement to that of an AND gate. A LOW (0) output results only if all the inputs to the gate are HIGH (1); if any input is LOW (0), a HIGH (1) output results. A NAND gate is made using transistors and junction diodes. By De Morgan's laws, a two-input NAND gate's logic may be expressed as =+, making a NAND gate equivalent to inverters followed by an OR gate. 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. It shares this property with the

NOR gate The NOR gate is a digital logic gate that implements logical NOR - it behaves according to the truth table to the right. A HIGH output (1) results if both the inputs to the gate are LOW (0); if one or both input is HIGH (1), a LOW output (0 ...

. Digital systems employing certain logic circuits take advantage of NAND's functional completeness. The function is logically equivalent to One way of expressing A NAND B is

\overline

, where the symbol

signifies AND and the bar signifies the negation of the expression under it: in essence, simply

. NAND gates with two or more inputs are available as integrated circuits in transistor-transistor logic, CMOS, and other logic families.

Symbols

There are three symbols for NAND gates: the MIL/ ANSI symbol, the IEC symbol and the deprecated

DIN DIN or Din or din may refer to: People and language * Din (name), people with the name * Dīn, an Arabic word with three general senses: judgment, custom, and religion from which the name originates * Dinka language (ISO 639 code: din), spoken by ...

symbol sometimes found on old schematics. For more information see logic gate symbols. The ANSI symbol for the NAND gate is a standard AND gate with an inversion bubble connected.

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, two-input, NAND gates.

Availability

These devices are available from most semiconductor manufacturers such as Fairchild Semiconductor,

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or Texas Instruments. These are usually available in both through-hole DIL and SOIC format. Datasheets are readily available in most datasheet databases. The standard 2-, 3-, 4- and 8-input NAND gates are available: * CMOS ** 4011: Quad 2-input NAND gate ** 4023: Triple 3-input NAND gate ** 4012: Dual 4-input NAND gate ** 4068: Mono 8-input NAND gate * TTL ** 7400: Quad 2-input NAND gate ** 7410: Triple 3-input NAND gate ** 7420: Dual 4-input NAND gate ** 7430: Mono 8-input NAND gate

Implementations

Functional completeness

The NAND gate has the property of functional completeness, which it shares with the

. That is, any other logic function (AND, OR, etc.) can be implemented using only NAND gates.Mano, M. Morris and Charles R. Kime. ''Logic and Computer Design Fundamentals, Third Edition.'' Prentice Hall, 2004. p. 73. An entire processor can be created using NAND gates alone. In TTL ICs using multiple-emitter transistors, it also requires fewer transistors than a NOR gate. As NOR gates are also functionally complete, if no specific NAND gates are available, one can be made from NOR gates using NOR logic.

References

External links

TTL NAND and AND gates
– All About Circuits {{Logical connectives NAND gate