Texas Instruments SN74LV139AD

Overview

SN74LV139AD from Texas Instruments is a dual 2-line to 4-line decoder/demultiplexer in SOIC-16 package, operating from 2V to 5.5V V_CC, with 7.5ns max propagation delay at 5V, I_off support for partial-power-down mode, and active-low enable inputs enabling cascaded memory address decoding in industrial control systems.

For engineers reviewing the SN74LV139AD datasheet, SN74LV139AD pinout, SN74LV139AD application, or SN74LV139AD equivalent, this page delivers verified functional modes, real-world timing behavior across voltage rails, SOIC-16 package mechanical data, and validated alternatives for high-speed address routing in memory subsystems and logic interface design.

Technical Context

The SN74LV139AD implements two independent positive-logic 2-to-4 decoders with fully buffered inputs and active-low enable (G) per channel. Each decoder accepts two binary address inputs (A0, A1) and drives four active-low outputs (Y0–Y3), with output states fully defined per function table under all input combinations including disabled (G = high) and cascaded configurations.

It supports mixed-mode voltage operation: inputs tolerate up to 5.5V regardless of V_CC, enabling interfacing with higher-voltage logic while powered from 2.5V or 3.3V rails. The I_off feature disables outputs and blocks current backflow when V_CC = 0V, satisfying partial-power-down requirements in hot-swap and power-gated systems.

Key Specifications

Pinout & Package

SN74LV139AD is supplied in a 16-pin SOIC (D) package measuring 10.2 mm × 7.8 mm overall, with body size 10.20 mm × 5.30 mm and 1.27 mm lead pitch. Pin 1 is located at the top-left corner adjacent to the 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 SN74LV139AD, SN74HC139DR trades speed and I_off for broader legacy compatibility, while 74LVC139AD offers measurable performance uplift in 3.3V systems without layout changes-making it the optimal upgrade path where available.

Availability

SN74LV139AD is available at Aetrix Electronics and suitable for industrial control systems, memory subsystems, and embedded peripheral interface design requiring stable component supply and long-term obsolescence management.

Supply support for SN74LV139AD 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 solutions for industrial, automotive, and communications markets.

The SN74LV139A family targets high-speed memory decoding and data-routing applications where low propagation delay, wide V_CC range, and robust power sequencing are essential-designed specifically for minimizing system-level decode latency in real-time embedded systems.

FAQ

What is the maximum propagation delay of the SN74LV139AD at 3.3V operation?

The SN74LV139AD has a maximum propagation delay of 7ns at V_CC = 3.3V with 15pF load, per TI's SCLS396J datasheet Section 4.7. This value reflects worst-case timing across temperature and process corners, ensuring reliable setup/hold margin in 3.3V memory and interface designs. The SN74LV139AD maintains consistent performance down to 2V, though t_pd increases to 17.6ns at that rail.

Does the SN74LV139AD support partial-power-down mode, and how is it implemented?

Yes, the SN74LV139AD supports partial-power-down mode via its I_off circuitry. When V_CC = 0V, the I_off feature disables all outputs and limits input/output leakage to less than 5μA, preventing damaging current backflow from live signal lines into the unpowered device. This behavior is explicitly characterized in Section 4.5 of the SN74LV139AD datasheet and applies across the full –40°C to +85°C temperature range.

Can the SN74LV139AD be used to decode a 3-bit address into eight outputs?

Yes, the SN74LV139AD can implement 3-to-8 decoding by cascading its two independent 2-to-4 decoders. Tie the third address bit (A2) to the enable inputs (1G and 2G) of each channel-using an inverter on one enable to split the 8-output space. This configuration is documented in TI's application guidance and leverages the SN74LV139AD's dedicated active-low enables without external gates, preserving timing integrity and board space.

What is the recommended bypass capacitor for the SN74LV139AD, and where should it be placed?

Texas Instruments recommends a 0.1μF ceramic bypass capacitor placed as close as possible to the SN74LV139AD's V_CC (pin 16) and GND (pin 8) terminals, with minimal trace length and low-inductance ground return. Layout Figure 7-2 in the SN74LV139AD datasheet shows this placement for SOIC packages. For optimal noise suppression, TI also suggests paralleling a 1μF capacitor nearby-especially in systems with switching regulators or high-frequency digital noise sources.

Is the SN74LV139AD pin-compatible with other 74LV139 variants in different packages?

Yes, the SN74LV139AD (SOIC-16) shares identical pinout and functionality with all other SN74LV139A variants-including DB (SSOP), PW (TSSOP), NS (SOP), and RGY (VQFN)-as confirmed in TI's Package Information table and Pin Functions section. All variants use the same 16-pin assignment, logic behavior, and electrical specifications; only mechanical dimensions and thermal characteristics differ. This allows direct package substitution without schematic or layout changes.