Texas Instruments CD74HC139EG4

Overview

CD74HC139EG4 from Texas Instruments is a dual 2-to-4 line decoder/demultiplexer in the high-speed CMOS HC logic family, operating from 2V to 6V with active-low mutually exclusive outputs, -55°C to +125°C temperature range, and propagation delay of 25 ns (typ) at 6V. It serves as a memory address decoder or data routing switch in industrial control and instrumentation systems.

For engineers reviewing the CD74HC139EG4 datasheet, CD74HC139EG4 pinout, CD74HC139EG4 application, or CD74HC139EG4 equivalent, key selection criteria include its dual-decoder architecture, active-low enable and output logic, wide supply voltage tolerance, LSTTL load drive capability (10 loads), and compatibility with legacy CD4556B designs.

Technical Context

The CD74HC139EG4 integrates two independent binary-to-1-of-4 decoders, each with a dedicated active-low enable input (1E/2E) and two select inputs (A0/A1). Outputs are active-low and mutually exclusive: only one Y0–Y3 goes low per decoder when enable is asserted.

It functions as a demultiplexer when the enable input carries data and select lines route it to one of four outputs; cascading is supported via enable chaining. The device is functionally identical to CD4556B and pin-compatible with it, enabling drop-in replacement in legacy 4000-series designs.

Key Specifications

Pinout & Package

CD74HC139EG4 is supplied in a 16-pin plastic dual in-line package (PDIP), with 0.3-inch body width and through-hole mounting. Pin 1 is marked by a notch or dot; pin numbering follows standard DIP convention (counterclockwise from top-left).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual 2-to-4 decoder/demultiplexer applications.

Compared with CD74HCT139E and SN74LS139N, CD74HC139EG4 delivers broader voltage operation, lower static current, and guaranteed -55°C to +125°C performance - making it optimal for new industrial, aerospace, and battery-sensitive designs where supply headroom and thermal robustness matter.

Availability

CD74HC139EG4 is available at Aetrix Electronics and suitable for memory decoding, data routing, code conversion, and industrial control applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC139EG4 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 delivering analog, embedded processing, and logic solutions with emphasis on reliability, longevity, and industrial-grade qualification.

The CD74HC139EG4 belongs to TI's legacy high-speed CMOS logic portfolio, engineered for robust, low-power decoding and demultiplexing in harsh-environment systems where pin compatibility and wide supply tolerance are critical.

FAQ

What is the supply voltage range for CD74HC139EG4?

The CD74HC139EG4 operates from 2V to 6V DC. This wide range allows direct use in both 3.3V and 5V systems, eliminates need for level shifters in mixed-voltage designs, and supports battery-backed or wide-input industrial power rails. Operation outside this range may cause permanent damage.

Is CD74HC139EG4 pin-compatible with CD4556B?

Yes, CD74HC139EG4 is pin-compatible and functionally identical to CD4556B. Both share the same 16-pin PDIP footprint, identical pin assignments (including enable, select, and output mapping), and matching truth table behavior - enabling drop-in replacement in legacy 4000-series designs without PCB changes.

What is the maximum propagation delay of CD74HC139EG4 at 5V?

At VCC = 5V and CL = 50 pF, the maximum propagation delay for CD74HC139EG4 is 36 ns (select-to-output) and 34 ns (enable-to-output), per the datasheet's -40°C to +85°C specification. At 25°C, typical delay is 29 ns, supporting reliable operation in sub-30 MHz timing-critical paths.

Can CD74HC139EG4 drive standard TTL loads?

Yes, CD74HC139EG4 can drive up to 10 LSTTL loads per output. Its output structure delivers VOH ≥ 4.4V and VOL ≤ 0.1V at VCC = 4.5V, meeting TTL input thresholds (VIH ≥ 2V, VIL ≤ 0.8V) with margin - enabling direct connection to 74LSxx and 74ALSxx families without buffers.

Does CD74HC139EG4 support cascading for larger decode functions?

Yes, CD74HC139EG4 supports cascading: the active-low enable inputs (1E, 2E) double as chip-select lines. By connecting one decoder's outputs to another's enable, designers can build 3-to-8 or 4-to-16 decoders. The truth table explicitly defines enable priority, ensuring deterministic behavior during expansion.