Texas Instruments SN74HC139DBR

Overview

SN74HC139DBR from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in SSOP-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 industrial control and instrumentation systems.

For engineers reviewing the SN74HC139DBR datasheet, SN74HC139DBR pinout, SN74HC139DBR application, or SN74HC139DBR equivalent, this page delivers verified electrical specs, functional pin mapping, real-world use cases, and validated alternative options for logic-level signal routing and enable-controlled data distribution.

Technical Context

The SN74HC139DBR integrates two independent decoders, each with active-low enable (G) and binary-select inputs (A, B), producing four active-low outputs (Y0–Y3). Each decoder operates as a 2-to-4 line decoder or 1-to-4 demultiplexer depending on input configuration.

It uses CMOS technology with fully buffered inputs, presenting only one normalized load to the driving circuit. The device supports cascading via shared or independent enable lines and exhibits rail-to-rail output swing compatible with LSTTL loads.

Key Specifications

Pinout & Package

SN74HC139DBR is housed in a 16-pin SSOP (Shrink Small Outline Package) with body dimensions 6.20 mm × 5.30 mm and 0.65 mm lead pitch. Pin 1 is located at the top-left corner with a molded index notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC139DBR, SN74HC139DR offers mechanical compatibility with legacy SOIC layouts but sacrifices board density, while 74LVC139PW delivers superior speed at 3.3 V but forfeits 6 V tolerance and full LSTTL drive strength - making SN74HC139DBR the optimal balance for industrial 5 V systems needing compactness and robustness.

Availability

SN74HC139DBR is available at Aetrix Electronics and suitable for industrial control panels, test equipment signal routing, and memory expansion modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74HC139DBR 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 founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and aerospace qualification.

The SN74HC139DBR belongs to TI's 74HC logic family - designed for high-speed, low-power, TTL-compatible digital interfacing in cost-sensitive and thermally constrained applications.

FAQ

What is the maximum clock frequency supported by SN74HC139DBR?

SN74HC139DBR is not a clocked device and has no internal clock - it is a combinational logic decoder. Its usable switching rate depends on input transition time and load capacitance. With CL = 50 pF and VCC = 5 V, maximum reliable toggle rate is ~10 MHz based on 10 ns tpd and 19 ns total cycle time (tpd + tt), assuming clean edges and proper bypassing.

Can SN74HC139DBR operate at 3.3 V?

Yes, SN74HC139DBR is fully specified from 2 V to 6 V, including 3.3 V operation. At 3.3 V, VOH is guaranteed ≥3.15 V and VOL ≤0.33 V under 4 mA load, ensuring compatibility with 3.3 V LVTTL and most microcontroller I/Os. Propagation delay increases to ~18 ns typical.

Is SN74HC139DBR RoHS compliant and lead-free?

Yes, SN74HC139DBR is RoHS compliant and features NiPdAu (NIPDAU) lead finish. Per TI's packaging addendum, it carries MSL Level-1 rating with unlimited floor life and peak reflow tolerance up to 260 °C - suitable for standard Pb-free SMT assembly processes.

How are the two decoders in SN74HC139DBR isolated from each other?

The two decoders in SN74HC139DBR are electrically isolated - they share only VCC and GND rails. Each has dedicated A/B select inputs and G enable, with no internal signal coupling. This allows independent operation: e.g., G1 can disable channel 1 while G2 enables channel 2, or both can be synchronized for parallel decoding.

What happens to outputs when the enable (G) input is high?

When G is high (logic 1), all four corresponding outputs (Y0–Y3) are forced high-impedance - effectively disabled. This is confirmed in the Functional Modes table: "G = H → Y0–Y3 = H regardless of A/B state." Outputs remain at valid logic-high voltage (VCC) due to internal pull-up structure, not floating.