SN74HC138PW

Updated: 2026-09-12

Overview

The SN74HC138PW is a high-performance 3-to-8 line decoder/demultiplexer integrated circuit (IC) manufactured by Texas Instruments. It is part of the HC (High-Speed CMOS) family, known for its balance of speed and power efficiency. This IC is widely used in digital systems for address decoding, memory selection, and data routing. Designed for robustness, the SN74HC138PW operates over a wide voltage range (2V to 6V) and features high noise immunity, making it suitable for industrial and automotive applications. Its TSSOP-16 package ensures compactness, ideal for space-constrained designs.

Structure and Working Principle

The SN74HC138PW consists of three binary select inputs (A0, A1, A2) and eight active-low outputs (Y0 to Y7). It decodes a 3-bit binary input into one of eight mutually exclusive outputs. The device also includes three enable inputs (G1, G2A, G2B) for cascading and control. When enabled, the selected output goes low (logic 0) based on the input combination, while all other outputs remain high (logic 1). This functionality makes it useful for memory addressing, peripheral selection, and signal routing in multiplexed systems.

Key Features

The SN74HC138PW offers several advantages for digital designers. Its low power consumption (typical ICC of 4µA) makes it energy-efficient, while its high-speed operation (propagation delay of 13ns at 5V) ensures quick response times. Additionally, the IC is designed for compatibility with both TTL and CMOS logic levels, simplifying integration into mixed-logic systems. Its wide operating temperature range (-40°C to 85°C) and robust construction make it reliable for harsh environments.

Application Areas

This decoder/demultiplexer is commonly used in microprocessor and microcontroller systems for memory address decoding, enabling efficient use of address space. It's also found in industrial automation systems for signal distribution and control logic. Other applications include LED matrix control, where it selects individual LEDs, and in communication systems for channel selection. Automotive electronics benefit from its reliability in engine control units and infotainment systems.

Maintenance and Precautions

To ensure long-term reliability, the SN74HC138PW should be protected from electrostatic discharge (ESD) during handling and installation. Proper decoupling capacitors (0.1µF) should be placed near the power pins to minimize noise. Designers should avoid exceeding the absolute maximum ratings, particularly the supply voltage (7V) and input voltage range (VCC + 0.5V). Thermal considerations are minimal due to the low power dissipation, but adequate ventilation should be maintained in high-density PCB layouts.

B2B Procurement Guide

When procuring the SN74HC138PW in bulk, verify the manufacturer's authenticity to avoid counterfeit parts. Texas Instruments offers direct purchasing through their website and authorized distributors. Consider lead times, especially for TSSOP-16 packaged versions, and request samples for prototype testing. MOQ (Minimum Order Quantity) typically starts at 1,000 units for best pricing, with volume discounts available. Environmental compliance (RoHS, REACH) should be confirmed for regulatory requirements.