Nexperia USA Inc. 74HC138PW,112

Overview

74HC138PW,112 from NXP Semiconductors is a 3-to-8 line decoder/demultiplexer in TSSOP-16 package, operating at 2V–6V supply, with propagation delay of 19 ns (typ. at 4.5V), fan-out of 10 LSTTL loads, and output drive capability of ±4 mA. It enables address decoding in microcontroller-based memory expansion systems.

For engineers reviewing the 74HC138PW,112 datasheet, 74HC138PW,112 pinout, 74HC138PW,112 application, or 74HC138PW,112 equivalent, key selection criteria include enable logic configuration (active-low G1, active-high G2A/G2B), output polarity (active-low Y0–Y7), and compatibility with 74HCT-level input thresholds in mixed-voltage systems.

Technical Context

This device implements three enable inputs (G1, G2A, G2B) controlling all eight decoded outputs simultaneously. When enabled, it translates three binary address inputs (A0–A2) into one of eight mutually exclusive active-low outputs (Y0–Y7).

The 74HC138PW,112 uses silicon-gate CMOS technology for low static power consumption (max 80 µA at 6V) and high noise immunity (min 30% VCC). All inputs tolerate 7V, supporting hot-swap and mixed-logic interfacing.

Key Specifications

Pinout & Package

TSSOP-16 (Thin Shrink Small Outline Package), 4.4 mm × 5.0 mm body, 0.65 mm pitch, thermally enhanced pad optional.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder applications.

Compared with 74HC138PW,112, the 74HCT138PW,118 offers guaranteed TTL input compatibility at 5 V, while SN74HC138PWR provides broader temperature certification and marginally higher supply current-both retain identical decode functionality and PCB footprint.

Availability

74HC138PW,112 is available at Aetrix Electronics and suitable for memory address decoding, LED multiplexing, I/O port expansion, and industrial control logic requiring stable component supply and long-term manufacturability.

Supply support for 74HC138PW,112 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The 74HC logic family delivers high-speed, low-power CMOS alternatives to legacy TTL, designed specifically for noise-immune digital control in resource-constrained embedded systems.

FAQ

Can 74HC138PW,112 operate at 3.3 V supply?

Yes. The 74HC138PW,112 is fully specified from 2.0 V to 6.0 V, including 3.3 V operation. At VCC = 3.3 V, propagation delay is 22 ns (typ.), output drive is ±3.5 mA, and input thresholds scale proportionally (VIH ≈ 2.0 V, VIL ≈ 0.9 V), ensuring reliable interface with 3.3 V microcontrollers.

What happens when multiple enable inputs are mismatched?

All three enables (G1, G2A, G2B) must satisfy their logic conditions simultaneously for any output to activate. If G1 = LOW or either G2A/G2B = HIGH, all Y0–Y7 remain HIGH (inactive). This prevents partial decoding and ensures fail-safe behavior during power-up or reset transitions.

Is thermal pad connection required in TSSOP-16 layout?

No. The 74HC138PW,112 in TSSOP-16 (SOT403-1) does not include an exposed thermal pad per NXP's package drawing. Standard solder mask-defined pads and 0.65 mm pitch routing are sufficient; no thermal via array or copper pour is needed for normal operation up to 125 °C ambient.

How does output loading affect propagation delay?

Propagation delay increases linearly with capacitive load. With 50 pF load, tPD rises to 25 ns (typ. at 4.5 V); with 15 pF (standard test condition), it remains 19 ns. Designers should limit trace capacitance and avoid driving >2 standard TTL loads per output to maintain timing integrity.