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7420 IC – Dual 4-Input NAND Gate (DIP-14)
🔲 7420 IC – Dual 4-Input NAND Gate (DIP-14)
The 74LS20 or 7420 is a TTL logic IC that contains two independent 4-input NAND gates. Each gate performs the NAND logic function: the output is LOW only when all four inputs are HIGH. This IC is widely used in digital logic circuits, timing, gating, and combinational logic applications.
⚙️ Technical Specifications
| Parameter | Specification |
|---|---|
| Logic Family | TTL (74 series) |
| Function | Dual 4-input NAND gates |
| Number of Gates | 2 |
| Number of Inputs/Gate | 4 |
| Package Type | DIP-14 |
| Supply Voltage (Vcc) | 4.75V to 5.25V (typically 5V) |
| Input Logic Levels | LOW ≤ 0.8V, HIGH ≥ 2V |
| Output Drive Current | ~8 mA |
| Operating Temperature | 0°C to +70°C (Standard TTL range) |
📌 Pin Configuration (DIP-14)
| Pin | Function | Pin | Function |
|---|---|---|---|
| 1 | A1 (Input 1) | 14 | Vcc |
| 2 | B1 (Input 2) | 13 | D2 (Input 4) |
| 3 | C1 (Input 3) | 12 | C2 (Input 3) |
| 4 | D1 (Input 4) | 11 | B2 (Input 2) |
| 5 | Y1 (Output 1) | 10 | A2 (Input 1) |
| 6 | A2 (Input 1) | 9 | Y2 (Output 2) |
| 7 | GND | 8 | NC (No Connect) |
🧠 Logic Truth Table for 1 Gate (A, B, C, D → Y)
| A | B | C | D | Y (Output) |
|---|---|---|---|---|
| 0 | X | X | X | 1 |
| 1 | 0 | X | X | 1 |
| 1 | 1 | 0 | X | 1 |
| 1 | 1 | 1 | 0 | 1 |
| 1 | 1 | 1 | 1 | 0 |
Y = NOT (A AND B AND C AND D)
Output goes LOW only when all inputs are HIGH
🛠️ Applications
Logic building blocks
Enable/disable control signals
Digital gating and masking
Timing and clock control
Used in counters and decoders