Gourt Home::Gourt :: NAND gate
Function
| 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.
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:| 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:| 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.
"NAND gate"