74HC251 Multiplexer/Demultiplexer Integrated Circuit  DIP‑16

The 74HC251 is a high-speed Si-gate CMOS 8-input multiplexer designed for modern digital systems. Housed in a DIP‑16 package, it offers low power consumption, fast switching, and robust ESD protection—ideal for microcontroller projects, Arduino and Raspberry Pi prototyping, and general-purpose electronics components and modules.

Key Features ⚡

• High-speed Si-gate CMOS technology for fast, reliable logic switching
• 8‑input multiplexer with 3‑bit binary selection for efficient signal routing
• Low power consumption suitable for battery-powered designs
• JEDEC compliant: standard no. 7A
• ESD protection: HBM JESD22‑A114F > 2000 V; MM JESD22‑A115‑A > 200 V 🔒

Technical Specifications 📐

• Supply Voltage Range: 2.0 to 6.0 V
• Operating Temperature Range: −40 to +125 °C
• Input transition rise/fall rate: ≤ 6 ns/V
• Output transition rise/fall rate: ≤ 6 ns/V
• Propagation delay: ≤ 20 ns
• Package: DIP‑16, breadboard‑friendly

Overview 🧠

Functionally, the 74HC251 selects one of eight digital inputs and forwards it to a single output based on a 3‑bit address. This makes it excellent for reducing I/O pin usage, implementing data gating, and managing signal direction on shared buses. While primarily an 8:1 multiplexer, it can be integrated into systems that perform demultiplexing in time‑division or bus‑oriented architectures.

Typical Applications 🧰

• Digital data manipulation and selection
• Signal direction control on shared buses
• Data gating for enabling/disabling signal paths
• Arithmetic logic and state‑machine control
• Control systems in embedded and industrial designs
• Multiplexing sensor or peripheral lines in Arduino/Raspberry Pi projects

Integration Notes for Arduino & Raspberry Pi 🤝

• Voltage: Operates from 2.0–6.0 V, making it suitable for 3.3 V (e.g., Raspberry Pi) and 5 V (many Arduino boards) systems.
• For Raspberry Pi GPIO safety, power the IC at 3.3 V or use level shifting if the IC is powered at 5 V.
• Use proper decoupling (e.g., 0.1 µF ceramic capacitor close to VCC/GND) to maintain signal integrity at high speeds.

Why Choose This IC? ✅

• Fast, CMOS performance with tight timing (≤ 20 ns)
• Wide temperature and voltage ranges for robust designs
• Strong ESD immunity for reliable handling and assembly
• Breadboard‑friendly DIP‑16 for rapid prototyping and hobbyist projects