Texas Instruments SN74HC139DRE4

Overview

SN74HC139DRE4 from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in SOIC-16 package, operating from 2 V to 6 V, with typical propagation delay of 10 ns at 5 V, ±4-mA output drive, and low ICC of 80 μA max - used for high-speed memory decoding and address demultiplexing in microcontroller peripheral interfaces.

For engineers reviewing the SN74HC139DRE4 datasheet, SN74HC139DRE4 pinout, SN74HC139DRE4 application, or SN74HC139DRE4 equivalent, key selection criteria include enable-controlled output gating, LSTTL-load compatibility (up to 10 loads), dual independent decoder channels, and CMOS-level input thresholds across supply range.

Technical Context

The SN74HC139DRE4 integrates two fully buffered 2-to-4 decoders sharing no internal logic; each has dedicated active-low enable (G) and binary select inputs (A, B), allowing independent channel control. Outputs are active-low open-drain–compatible with standard CMOS logic levels.

Each decoder implements truth-table-driven selection where only one output (Y0–Y3) goes low per valid input combination; all outputs default high when G is asserted. Input transition times are specified down to 400 ns at 6 V, supporting clean switching in synchronous digital systems.

Key Specifications

Pinout & Package

SN74HC139DRE4 uses a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm with standard 1.27-mm lead pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar decoder/demultiplexer applications.

Compared with SN74HC138DR and 74LVC139AD,118, the SN74HC139DRE4 uniquely delivers dual independent decoders with per-channel active-low enables in a single SOIC-16 package - critical for space-constrained industrial controllers requiring isolated memory and peripheral decode paths.

Availability

SN74HC139DRE4 is available at Aetrix Electronics and suitable for industrial control panels, embedded instrumentation, and legacy microcontroller upgrade programs requiring stable component supply and long-term manufacturability.

Supply support for SN74HC139DRE4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic ICs with over 50 years of innovation in industrial, automotive, and communications markets.

The SN74HC139DRE4 belongs to TI's HC logic family, designed for high-speed, low-power decoding and demultiplexing in resource-constrained embedded systems where reliability and wide supply tolerance are essential.

FAQ

What is the maximum clock frequency supported by SN74HC139DRE4 for reliable decoding?

The SN74HC139DRE4 does not operate on a clock; it is combinational logic. Its usable input transition rate is governed by propagation delay and input rise/fall time specs: at 6 V, max Δt/Δv is 400 ns, supporting effective address change rates up to ~2.5 MHz in worst-case timing paths. For SN74HC139DRE4, timing margins must be verified against system setup/hold requirements, not clock frequency.

Can SN74HC139DRE4 drive LEDs directly without current-limiting resistors?

No - SN74HC139DRE4 outputs are not designed for direct LED drive without external current limiting. While it sources/sinks up to ±4 mA at 5 V, forward voltage and LED variation make resistor-based current control mandatory. For SN74HC139DRE4, always use series resistors (e.g., 330 Ω for 5-V red LEDs) to ensure consistent brightness and prevent output stage overstress.

Is SN74HC139DRE4 pin-compatible with older SN74LS139 devices?

No - SN74HC139DRE4 and SN74LS139 share functional equivalence but differ electrically and physically: LS versions use bipolar technology, require 5-V-only supply, draw higher current, and have different DC thresholds. Though both are 16-pin SOIC, SN74HC139DRE4's CMOS inputs and wider voltage range mean direct substitution may cause logic level mismatches or timing violations unless system-level validation is performed.

How should unused inputs be handled on SN74HC139DRE4?

All unused inputs on SN74HC139DRE4 must be tied to a defined logic level - either VCC or GND - to prevent floating nodes that cause increased ICC, noise susceptibility, or erratic output behavior. For example, if only Channel 1 is used, tie G2, A2, and B2 to VCC or GND per functional intent; never leave them unconnected. This requirement applies to every SN74HC139DRE4 instance in the design.

Does SN74HC139DRE4 support hot-swap or live-insertion?

No - SN74HC139DRE4 is not hot-swap rated. Its absolute maximum ratings specify no exposure to VCC before GND stabilization, and undefined states during partial power-up can cause latch-up or excessive current draw. For systems requiring live insertion, add power sequencing circuitry or buffer isolation; SN74HC139DRE4 must be powered within recommended conditions before signal application.