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NAND gate
From Wikipedia, the free encyclopedia
| INPUT A B |
OUTPUT 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.The nand gate is a universal gate in the sense that any boolean function can be implemented by nand gates.
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There are two symbols for NAND gates: the 'military' symbol and the 'rectangular' symbol. For more information see logic gate symbols.
NAND gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs.
The standard, 4000 series, CMOS IC is the 4011, which includes four independent, two-input, NAND gates. The pinout diagram is as follows:
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 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
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.
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
The NAND gate is the easiest to manufacture, and also 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.
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