74LS21 DUAL 4-INPUT AND GATE
The 74LS21 is a versatile digital logic IC that contains two independent 4-input AND gates in one package. It is built using Low Power Schottky Transistor-Transistor Logic (TTL) technology, ensuring minimal propagation delay and reliable logic performance.
Each AND gate produces a HIGH output only when all four inputs are HIGH, making this IC a suitable choice for creating conditional logic functions in control panels, logic circuits, and digital decision-making systems.
Due to its robust TTL design and compact DIP-14 packaging, the 74LS21 is ideal for both hobbyists and professionals designing digital systems, automation solutions, or educational logic trainers.
🛠 Technical Details
| Specification | Details |
|---|---|
| Logic Family | 74LS (Low Power Schottky TTL) |
| Function | Dual 4-input AND gate |
| Operating Voltage (Vcc) | 4.75V – 5.25V (typically 5V) |
| High-Level Output Current | -0.4 mA |
| Low-Level Output Current | 8 mA |
| Propagation Delay | ~15 ns (typical) |
| Package | DIP-14 or SOIC-14 |
| Operating Temperature | 0°C to +70°C |
| Number of Gates | 2 (each with 4 inputs) |
| Input Compatibility | Standard TTL |
💡 Use Cases & Applications
-
✅ Digital Logic Controllers – Combine multiple conditions like switches, sensors, or control signals for precise system actions.
-
✅ Security Access Systems – Require multiple simultaneous HIGH signals (e.g., all sensors ON) to unlock or enable functionality.
-
✅ Embedded Systems – Gate microcontroller outputs for power control, error signaling, or boot logic.
-
✅ Educational Kits & Labs – Used in logic trainers to demonstrate AND gate behavior in practical scenarios.
-
✅ Signal Verification Circuits – Ensure all signals are high before activating the next stage in a digital flow.
🛠️ Pair With
-
🔌 IC’s Collection – Discover more digital ICs like OR, NAND, XOR gates.
-
🔧 Tools & Accessories – Great for soldering and prototyping tools.
-
⚙️ Power Supply Units – Use a clean 5V regulated source for stable TTL logic.
🎥 YouTube Tutorial
📺 Watch Tutorial: Search “74LS21 AND Gate Circuit Demo”
Understand how the 4-input logic structure works in a real breadboard setup.
⚠️ Precautions & Tips
-
Always power with regulated 5V DC for TTL performance.
-
Tie unused inputs to logic LOW or HIGH to prevent floating behavior.
-
Use 0.1μF bypass capacitors near the IC for noise reduction.
-
Avoid exceeding maximum current specs to protect gate integrity.
-
Keep traces short for higher signal integrity in PCB designs.
🏁 Summary & Call-to-Action
The 74LS21 Dual 4-Input AND Gate provides fast, reliable logic processing in compact form. Whether you’re working on industrial automation, embedded logic control, or academic learning tools, this IC delivers dependable performance.
🛒 Order now from Electroway and explore a broad collection of high-quality digital ICs and prototyping essentials.
Reviews
There are no reviews yet.