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7400 - Quad Two Input NAND Gate

7400 - Quad Two Input NAND Gate
7400 - Quad Two Input NAND Gate
74LS00 is part of the 74XXYY IC series. 74xxyy integrated circuits are logical gates of digital electronics. The 74LS00 IC has four NAND gates(NAND Gate is the combination of AND and NOT Gate). In addition, each door has two entrances. Hence the name QUAD TWO INPUT NAND GATE.
  
Pin Diagram of 7400 IC
7400 Pin DIagram
74LS00 is a 14-pin device. The chip is available in different packages and is chosen according to the needs. 

The description of each pin is given below.

Pin Number
Description
1
A1-INPUT1 of GATE 1
2
B1-INPUT2 of GATE 1
3
Y1-OUTPUT of GATE1
4
A2-INPUT1 of GATE 2
5
B2-INPUT2 of GATE 2
6
Y2-OUTPUT of GATE2
9
A3-INPUT1 of GATE 3
10
B3-INPUT2 of GATE 3
8
Y3-OUTPUT of GATE3
12
A4-INPUT1 of GATE 4
13
B4-INPUT2 of GATE 4
11
Y4-OUTPUT of GATE4
7
GND- Connected to ground
14
VCC-Connected to positive voltage to
provide smdksmkmpower to all four gates

 Internal Circuit Diagram of 7400 IC


7400 Internal Circuit Diagram
As you can see there are 4 NAND Gate inside 7400 IC and you can relate the Pin Description.

Below is the Truth Table of NAND Gate :

Input-1
Input-2
AND  O/P
NAND  O/P
1
1
1
0
0
1
0
1
1
0
0
1
0
0
0
1

NAND Gate using Transistors

7400 NAND Gate Equivalent Circuit Diagram

  • Both inputs A1 and B1 are LOW:
The two transistors Q1 and Q2 will be deactivated. Thus, the total supply voltage appears on the transistors Q1 and Q2. Since the output Y1 is only the voltage across the transistors Q1 and Q2, Y1 will be HIGH.
  • One of the Input is HIGH:
Only the relative transistor will be ON, leaving the other OFF. With this, the entire supply voltage appears on the transistor that is in the off state. As the output Y1 is the voltage across the two transistors Q1 and Q2, Y1 will be HIGH.
  • Both inputs are HIGH :
The two transistors will be ON and the voltage between them will be equal to zero. Because the output Y1 is the voltage at the two transistors Q1 and Q2, Y1 will be LOW.

After checking the cases, you can say that we have satisfied the truth table above. The output equation for the NAND gate can be given in the form, 7400 NAND Gate Equation

Applications


  • · General purpose logic
  • · Digital Electronics
  • · PCs and notebooks
  • · Servers
  • · ALUs
  • · Networking
  • · Digital systems

74LS00 Datasheet

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