NAND Gate Output Condition Explained
A NAND gate performs the logical AND operation followed by a logical NOT operation. Its output is the inverse of an AND gate's output.
The logical expression for a 2-input NAND gate is $Y = \overline{A \cdot B}$. For multiple inputs ($A_1, A_2, \ldots, A_n$), it is $Y = \overline{A_1 \cdot A_2 \cdot \ldots \cdot A_n}$.
The output ($Y$) of a NAND gate is LOW (0) only in one specific scenario: when all of its inputs are HIGH (1).
Let's look at the truth table for a standard 2-input NAND gate:
| Input A | Input B | Output Y = NOT (A AND B) |
|---|---|---|
| 0 (LOW) | 0 (LOW) | 1 (HIGH) |
| 0 (LOW) | 1 (HIGH) | 1 (HIGH) |
| 1 (HIGH) | 0 (LOW) | 1 (HIGH) |
| 1 (HIGH) | 1 (HIGH) | 0 (LOW) |
Determining LOW Output Condition
From the truth table and the definition, we can see that the output ($Y$) is LOW (0) only when Input A is HIGH (1) AND Input B is HIGH (1).
This principle extends to NAND gates with more inputs. The output remains HIGH if any input is LOW, and only drops to LOW when every single input is HIGH.
Therefore, the condition for the NAND gate output to be LOW is when all of the inputs are HIGH.
Similar Questions
In a logic circuit, two inputs A and B are applied to an AND gate, and the output of the AND gate is connected to the input of a NOT gate. If the inputs A and B are both at logic 0, what will be the output of the entire circuit?
In a logic circuit, three SPST (Single Pole Single Throw) switches are used to implement a logic gate. The switches are connected in series. What is the output of the circuit if all switches are closed?
_______ are universal logic gates.
- _____ is the digital 2-input logic gate whose output is HIGH only when both its inputs are the same.
- A three Input NOR gate gives high O/P when _____.
Important Questions from Logic Gates
Which logical gate is used to represent product of sum expression?
Which gate is represented by the following truth table?
Input
Output
A
B
C
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
0
Which logical gate is included in a binary adder circuit to enable binary addition and subtraction?
Which of the following represents the XNOR gate?
A Circuit that operates in such a way that its output is high only when all its inputs are high
