SN7420 Dual 4-Input NAND Gate IC – DIP-14
The SN7420 is a digital logic integrated circuit featuring two independent 4-input NAND gates in a single 14-pin DIP package. Part of the 7400-series TTL logic family, it is designed for digital circuit development, logic control, switching applications, and educational electronics projects.
Each NAND gate produces a LOW output only when all four inputs are HIGH. If any input is LOW, the output remains HIGH.
The SN7420 is suitable for breadboard prototyping, logic circuit experiments, and digital electronics applications.
Key Features
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Dual NAND Gates: Contains two independent 4-input NAND logic gates.
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TTL Logic: Part of the standard 7400-series logic family.
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5V Operation: Designed for standard 5V digital logic circuits.
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4 Inputs per Gate: Supports logic operations involving four independent inputs.
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DIP-14 Package: Convenient for breadboard prototyping and through-hole PCB assembly.
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Digital Logic Applications: Suitable for combinational logic, signal control, and logic experiments.
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Standard Logic Function: Output is LOW only when all four inputs are HIGH.
Technical Specifications
| Parameter |
Specification |
| Part Number |
SN7420 |
| IC Type |
Digital Logic IC |
| Logic Family |
7400 Series TTL |
| Logic Function |
NAND |
| Number of Gates |
2 |
| Inputs per Gate |
4 |
| Total Logic Inputs |
8 |
| Operating Voltage |
4.75–5.25V DC |
| Nominal Supply Voltage |
5V DC |
| Logic Output |
TTL |
| Package Type |
DIP-14 |
| Number of Pins |
14 |
| Mounting Type |
Through-Hole |
| Operating Temperature |
0°C to +70°C (standard 7420) |
Pin Configuration
| Pin |
Function |
Description |
| 1 |
1A |
Gate 1 Input A |
| 2 |
1B |
Gate 1 Input B |
| 3 |
NC |
No Internal Connection |
| 4 |
1C |
Gate 1 Input C |
| 5 |
1D |
Gate 1 Input D |
| 6 |
1Y |
Gate 1 Output |
| 7 |
GND |
Ground |
| 8 |
2Y |
Gate 2 Output |
| 9 |
2A |
Gate 2 Input A |
| 10 |
2B |
Gate 2 Input B |
| 11 |
NC |
No Internal Connection |
| 12 |
2C |
Gate 2 Input C |
| 13 |
2D |
Gate 2 Input D |
| 14 |
VCC |
+5V Power Supply |
NAND Gate Logic Operation
Each gate performs the following Boolean operation:
Y = NOT (A × B × C × D)
Truth Table
| A |
B |
C |
D |
Output Y |
| 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 |
X = Don't Care (either 0 or 1)
The output becomes LOW only when all four inputs are HIGH.
Connection Example
To operate the first NAND gate:
- Connect Pin 14 (VCC) to +5V DC.
- Connect Pin 7 (GND) to ground.
- Connect input signals to Pins 1, 2, 4, and 5.
- Read the output signal from Pin 6.
- Connect a 100nF decoupling capacitor between VCC and GND near the IC.
The second NAND gate can operate independently using Pins 9, 10, 12, and 13, with its output on Pin 8.
Applications
- Digital Logic Circuit Design
- Electronic Switching Circuits
- Logic Gate Experiments
- Educational Electronics Projects
- Combinational Logic Systems
- Digital Signal Control
- Logic Function Implementation
- Breadboard and PCB Prototyping
Important Notes
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Power Supply: Use a regulated 5V supply within the specified operating range.
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TTL Compatibility: Standard TTL HIGH-level output voltage is not guaranteed to meet every 5V CMOS input requirement.
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Microcontroller Compatibility: Do not connect 5V TTL outputs directly to 3.3V-only GPIO pins without checking electrical compatibility.
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Unused Inputs: Do not leave unused TTL inputs floating; connect them to a defined logic level.
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Package Orientation: Identify Pin 1 using the notch or orientation mark before connecting power.
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Decoupling: A 100nF capacitor across the supply pins is recommended.
Package Includes
