NAND gate

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This article is about NAND in the sense of an electronic logic gate (e.g. CMOS 4011). For NAND in the purely logical sense, see NAND. For logic gates generally, see logic gate

Contents

1 Function
2 Symbols
3 Hardware description and pinout

3.1 CMOS version
3.2 TTL version
3.3 Availability

4 Other

Function

INPUT OUTPUT
A B A NAND B
0 0 1
0 1 1
1 0 1
1 1 0

INPUT	OUTPUT
A	B	A NAND B
0	0	1
0	1	1
1	0	1
1	1	0

The NAND gate is a digital logic gate that behaves according to the truth table to the right. 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.

Symbols

There are two symbols for NAND gates: the 'military' symbol and the 'rectangular' symbol. For more information see logic gate symbols.

'Rectangular' NAND 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, two-input, NAND gates. The pinout diagram is as follows:

Pinout diagram of a 4011 quad NAND IC

1 Input A1 2 Input B1 3 Output Q1 4 Output Q2 5 Input B2 6 Input A2 7 Vss 8 Input A3 9 Input B3 10 Output Q3 11 Output Q4 12 Input B4 13 Input A4 14 Vdd

TTL version

The 4011's TTL counterpart is the 7400. Here is its pinout diagram, with a photo of a typical 7400 IC:

Pinout diagram and photo of a 7400 quad NAND IC

1 Input A1 2 Input B1 3 Output Q1 4 Input A2 5 Input B2 6 Output Q2 7 Ground 8 Output Q3 9 Input B3 10 Input A3 11 Output Q4 12 Input B4 13 Input A4 14 Vcc

Availability

These devices are available from most semiconductor manufacturers such as Fairchild Semiconductor, Philips or Texas Instruments. These are usually available in both through-hole DIL and SOIC format. Datasheets are readily available in most datasheet databases.

Besides the standard 2-input NAND gate, 3-, 4- and 8-input NAND gates are also available:

CMOS
* 4023: Triple 3-input NAND gate
* 4012: Dual 4-input NAND gate
* 4068: Mono 8-input NAND gate
TTL
* 7410: Triple 3-input NAND gate
* 7420: Dual 4-input NAND gate
* 7430: Mono 8-input NAND gate

Other

The NAND gate is the easiest to manufacture, and also has the property that any other logic gate can be made from a combination of NAND gates. Therefore, NAND gates usually form the basis of all other logic hardware.

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