Texas Instruments SN74HC139PW

Overview

SN74HC139PW from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in TSSOP-16 package, operating from 2 V to 6 V, with typical propagation delay of 10 ns at 5 V and ±4-mA output drive capability. It features two independent active-low enable inputs (G1, G2) for cascading or data gating, and is used in high-speed memory decoding and address demultiplexing in microcontroller peripheral interfaces.

For engineers reviewing the SN74HC139PW datasheet, SN74HC139PW pinout, SN74HC139PW application, or SN74HC139PW equivalent, key selection criteria include its dual-decoder architecture with separate enables, low ICC (80 μA max), TTL-load compatibility (up to 10 LSTTL), and TSSOP-16 footprint for space-constrained PCB layouts.

Technical Context

The SN74HC139PW implements two fully buffered CMOS decoders sharing no internal logic-each has dedicated A/B select inputs and active-low G enable, with outputs Y0–Y3 asserted low per binary input combination. All inputs exhibit high noise immunity (VIH ≥ 3.15 V at VCC = 4.5 V) and low input current (≤1 μA).

Its switching behavior is characterized by matched tpd (12–44 ns across VCC = 2–6 V, CL = 50 pF) and controlled output transition times (tt ≤ 19 ns), enabling deterministic timing in synchronous address decode trees without external latching.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm, 1.2 mm max height), JEDEC MO-153 compliant, with 0.65 mm lead pitch and exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC139PW, SN74HCT139PW offers guaranteed TTL input compatibility at the cost of higher static power, while 74LCX139MTCX trades 5 V operation for enhanced 3.3 V drive and lower supply flexibility-neither is pin-compatible with PW package variants of the LCX family.

Availability

SN74HC139PW is available at Aetrix Electronics and suitable for industrial control panels, medical instrumentation, and automotive body electronics requiring stable component supply and long-term manufacturability.

Supply support for SN74HC139PW 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 connectivity solutions with over 90 years of innovation in industrial, automotive, and consumer electronics.

The SN74HC139PW belongs to TI's HC logic family, designed for high-speed, low-power digital interfacing in resource-constrained embedded systems where predictable timing and wide supply tolerance are critical.

FAQ

What is the maximum clock frequency supported by SN74HC139PW in a decode application?

The SN74HC139PW does not operate on a clock; it is combinational logic. Its usable maximum toggle rate depends on propagation delay and system timing margins. With tpd = 12 ns (typ) at VCC = 6 V, it supports address decode cycles up to ~42 MHz in worst-case synchronous systems, assuming sufficient setup/hold time for downstream latches. SN74HC139PW performance is governed by input transition rates and load capacitance, not clock frequency.

Can SN74HC139PW drive LEDs directly?

SN74HC139PW can sink up to 4 mA per output at VCC = 5 V, which is sufficient for low-current indicator LEDs (e.g., 1–2 mA at 1.8 V forward voltage with 1.5 kΩ series resistor). However, it cannot drive medium-brightness or multiplexed displays requiring >10 mA. For such cases, use SN74HC139PW outputs to enable external transistor drivers. Always verify VOL ≤ 0.33 V under load per SN74HC139PW datasheet Section 5.4.

Is SN74HC139PW compatible with 3.3 V microcontrollers?

Yes. SN74HC139PW operates from 2 V to 6 V and has VIH = 1.35 V (min) at VCC = 3.3 V, ensuring reliable recognition of 3.3 V logic-high signals. Its outputs swing rail-to-rail, providing 3.3 V logic-high levels compatible with most 3.3 V peripherals. No level shifting is required when interfacing with 3.3 V MCUs, making SN74HC139PW ideal for mixed-voltage board designs.

How should unused inputs be handled on SN74HC139PW?

All unused inputs on SN74HC139PW must be terminated to a defined logic state-either VCC or GND-to prevent floating nodes that cause increased ICC, erratic outputs, or ESD susceptibility. TI recommends tying unused A/B/G inputs directly to VCC or GND with short traces. Do not leave them open. This requirement applies regardless of whether the associated decoder channel is active; floating inputs violate recommended operating conditions in SN74HC139PW datasheet Section 5.2.

Does SN74HC139PW support hot insertion or live swapping?

No. SN74HC139PW is not designed for hot insertion. Its absolute maximum ratings specify VCC must be powered before applying input signals (Section 5.1), and undefined states during partial power-up may cause latch-up or excessive current. For systems requiring field-replaceable modules, implement power sequencing controls or use hot-swap controllers upstream of SN74HC139PW. TI explicitly cautions against exceeding absolute ratings during insertion in Section 10.4 (ESD Caution).