Texas Instruments SN74AHC139PWR

Overview

SN74AHC139PWR from Texas Instruments is a dual 2-to-4 line decoder/demultiplexer IC designed for high-speed memory decoding and data-routing applications. It operates from 2 V to 5.5 V, delivers propagation delays as low as 4.4 ns (VCC = 5 V, CL = 15 pF), features two independent active-low enable inputs (1G, 2G), and provides eight CMOS-compatible outputs (1Y0–1Y3, 2Y0–2Y3) with balanced drive capability. It is commonly used to select among four memory or peripheral devices per channel in embedded microcontroller systems.

For engineers reviewing the SN74AHC139PWR datasheet, SN74AHC139PWR pinout, SN74AHC139PWR application, or SN74AHC139PWR equivalent, key selection criteria include supply voltage range (2–5.5 V), propagation delay at 3.3 V and 5 V, output drive strength (±8 mA at 5 V), ESD robustness (2000 V HBM), and TSSOP-16 package compatibility with space-constrained PCB layouts.

Technical Context

The SN74AHC139PWR implements two independent positive-logic 2:4 decoders, each with two address inputs (A1, A0) and one active-low enable (G). When G is low, outputs Y0–Y3 reflect the decoded 2-bit input; when G is high, all outputs are forced high. The device uses silicon-gate CMOS technology with balanced push-pull outputs capable of sourcing and sinking equal current.

It supports cascading via separate enables and functions as a demultiplexer by using the strobe input as data and address lines as select controls. Output logic states are active-low (outputs go low on selection), and unused inputs must be tied to VCC or GND to prevent floating-induced oscillation or excess power draw.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package: 5.00 mm × 6.4 mm body, 0.65 mm lead pitch, surface-mount, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC139PWR, the SN74AHC139PWR delivers 4× faster decoding critical for high-speed memory access; versus 74LVC139APW,118, it offers guaranteed pin compatibility and simpler enable control but trades off 1.8 V operation and marginal speed gain.

Availability

SN74AHC139PWR is available at Aetrix Electronics and suitable for industrial control panels, automotive body electronics, medical diagnostic equipment, and communications infrastructure requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74AHC139PWR 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, with decades of experience in high-reliability industrial and automotive-grade components.

The SN74AHC139PWR belongs to TI's advanced high-speed CMOS (AHC) logic family, engineered specifically for low-latency, low-power memory decoding and data-path routing in real-time embedded systems.

FAQ

What is the maximum clock or address transition rate supported by the SN74AHC139PWR?

The SN74AHC139PWR does not operate on a clock; it is combinatorial logic. Its input transition rate is specified as ≤20 ns/V at VCC = 5 V, meaning inputs must slew no slower than 20 ns per volt of swing (e.g., ≥250 ns for full 0→5 V transition). Exceeding this may cause increased dynamic power or metastability. The SN74AHC139PWR remains fully functional as long as input rise/fall times meet this spec and stay within absolute max ratings.

Can the SN74AHC139PWR outputs drive LEDs directly?

Yes - each SN74AHC139PWR output can sink up to 8 mA at VCC = 5 V with VOL ≤ 0.5 V, sufficient to illuminate standard 2 mA indicator LEDs with appropriate series resistors (e.g., 470 Ω for ~5 V supply). However, total device current must remain ≤75 mA (sum of all outputs + ICC), and thermal limits must be observed. For higher-current LEDs, external drivers are recommended.

Is the SN74AHC139PWR pin-compatible with the SN74LS139N?

No - the SN74AHC139PWR (TSSOP-16) and SN74LS139N (PDIP-16) share identical logic function and pin numbering, but differ in package, voltage range, drive strength, and timing. While the pinout map matches (1G, 1A0, 1A1, 1Y0–1Y3, GND, VCC, 2Y0–2Y3, 2A1, 2A0, 2G), the SN74AHC139PWR requires PCB redesign due to TSSOP footprint, and cannot replace LS logic in 5 V-only systems without verifying VIH/VIL margins and fanout.

How should unused inputs be terminated on the SN74AHC139PWR?

All unused inputs on the SN74AHC139PWR - including 1A0, 1A1, 1G, 2A0, 2A1, and 2G - must be tied to a valid logic level (VCC or GND) to prevent floating. TI recommends direct connection for permanently unused pins; for intermittently used pins, a 10 kΩ pull-up or pull-down resistor is acceptable. Leaving any input unconnected risks oscillation, excessive ICC, and potential device damage due to undefined internal node states.

Does the SN74AHC139PWR support 3-state (high-impedance) outputs?

No - the SN74AHC139PWR has standard push-pull CMOS outputs, not 3-state. Outputs are always driven either high or low (except during brief transition periods). When disabled (e.g., 1G = high), all 1Yx outputs are forced high - not high-impedance. For true 3-state behavior, consider alternatives like SN74AHC238 or discrete buffer solutions. This design choice simplifies timing but requires careful bus arbitration in shared-data applications.