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.
| 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.
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[edit] Symbols
There are two symbols for NAND gates: the 'military' symbol and the 'rectangular' symbol. For more information see logic gate symbols.
[edit] Hardware description and pinout
NAND gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs.
[edit] 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:
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
[edit] TTL version
The 4011's TTL counterpart is the 7400 from the 7400 series. Here is its pinout diagram, with a photo of a typical 7400 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
[edit] 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
[edit] Implementations
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.
| Image:NMOS NAND.png | Image:PMOS NAND.png | Image:TTL npn nand.svg |
