STMicroelectronics M74HC139B1R

Overview

M74HC139B1R from STMicroelectronics is a dual 2-to-4 decoder/demultiplexer in high-speed CMOS technology, featuring active-low enable inputs, symmetrical output drive (±4 mA), 13 ns typical propagation delay at 6 V, and operation across 2–6 V supply range. It serves as address decoder in microcontroller peripheral interfaces and data routing in industrial control logic.

For engineers reviewing the M74HC139B1R datasheet, M74HC139B1R pinout, M74HC139B1R application, or M74HC139B1R equivalent, key selection criteria include enable-input gating behavior, dual independent decode sections, guaranteed noise immunity (28% VCC), balanced tPLH/tPHL delays, and DIP-16 package compatibility with legacy 74-series layouts.

Technical Context

The M74HC139B1R implements two independent 2-to-4 decoders, each with separate active-low enable (1G, 2G) and address inputs (1A/1B, 2A/2B), driving four open-drain-compatible outputs per section (1Y0–1Y3, 2Y0–2Y3). All inputs include ESD protection diodes rated for ±20 mA transient current.

Propagation delay is split into address-to-output (tPLH/tPHL ≈ 13 ns typ. at VCC = 6 V) and enable-to-output (11 ns typ.), with symmetrical output impedance ensuring matched rise/fall times. The device operates over –55°C to +125°C and supports input rise/fall times up to 400 ns at 6 V.

Key Specifications

Pinout & Package

Package: Plastic DIP-16 (0.300″ wide), JEDEC MS-001, 16-pin through-hole. Pin pitch: 2.54 mm (0.100″), body width: 20.0 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC139N and CD74HC139E, the M74HC139B1R offers superior temperature range (–55°C to +125°C), lowest ICC (40 μA max.), and tightest propagation delay consistency-making it optimal for mission-critical embedded control where thermal stability and power predictability are mandatory.

Availability

M74HC139B1R is available at Aetrix Electronics and suitable for microcontroller peripheral decoding, industrial I/O expansion, legacy system bus interface, and test equipment signal routing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HC139B1R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The M74HC139B1R belongs to ST's high-reliability HC logic family, engineered for robust operation in harsh environments-including automotive engine control units and factory automation systems-where extended temperature range and noise immunity are non-negotiable.

FAQ

Is M74HC139B1R pin-compatible with 74LS139?

Yes, M74HC139B1R uses the same DIP-16 pinout and truth table as 74LS139, including active-low enables and outputs. However, it operates at 2–6 V (vs. 4.75–5.25 V for LS), delivers higher output drive (±4 mA vs. ±8 mA LS), and exhibits lower propagation delay (13 ns vs. 25 ns typical). No level-shifting is needed for 5 V systems.

Can M74HC139B1R drive LEDs directly?

No-its outputs are designed for logic-level interfacing, not current sourcing. While it can sink up to 4 mA per output, driving even a low-current LED (typically requiring 2–5 mA at ~1.8 V forward voltage) risks violating VOL spec (0.4 V max. at 4 mA) and may cause inconsistent brightness or logic-level corruption. Use a discrete transistor or dedicated LED driver.

What is the maximum input rise/fall time supported at 6 V?

At VCC = 6 V, the M74HC139B1R guarantees correct operation with input transition times up to 400 ns (tr/tf), per AC Electrical Characteristics table. Slower edges increase susceptibility to glitches near switching thresholds; for reliable demuxing of clocked address buses, keep tr/tf ≤ 100 ns to maintain timing margins.

Does M74HC139B1R require external pull-up resistors on outputs?

No-outputs are push-pull CMOS, not open-drain. Each Yx output actively drives high or low depending on decode state and enable status. Pull-ups are unnecessary and would create contention when the output is driven low, increasing power dissipation and potentially damaging the output stage.