Nexperia USA Inc. 74AHC138PW,118

Overview

74AHC138PW,118 from Nexperia is a high-speed CMOS 3-to-8 line decoder/demultiplexer with inverting outputs, pin-compatible with LSTTL. It features three binary address inputs (A0–A2), eight active-low mutually exclusive outputs (Y0–Y7), and three enable inputs (E1, E2 active LOW; E3 active HIGH), operating across –40 °C to +125 °C with V_CC = 2.0–5.5 V. It is widely used in memory chip select decoding and hierarchical address expansion in industrial control logic.

For engineers reviewing the 74AHC138PW,118 datasheet, 74AHC138PW,118 pinout, 74AHC138PW,118 application, or 74AHC138PW,118 equivalent, key selection criteria include propagation delay (≤10.5 ns at V_CC = 5 V, C_L = 50 pF), input voltage tolerance (VI up to 7.0 V), output drive capability (±25 mA), and TSSOP16 package compatibility with high-density PCB layouts.

Technical Context

The device implements a fully static CMOS decoder architecture with Schmitt-trigger inputs for noise immunity and balanced propagation delays between all address-to-output paths (A0–A2 → Y0–Y7) and enable-to-output paths (E1/E2/E3 → Yn). Its triple-enable logic (E1·E2·E3) enables cascading for 1-of-32 decoding without external logic.

It operates as an 8-output demultiplexer when one active-LOW enable (e.g., E1) serves as data input while E2 and E3 act as strobes - all unused enables must be hard-wired to valid logic states. Input levels are CMOS-compatible (VIH ≥ 3.85 V at V_CC = 5.5 V), and outputs drive TTL loads with VOH ≥ 3.7 V and VOL ≤ 0.55 V at 8 mA.

Key Specifications

Pinout & Package

TSSOP16 plastic thin shrink small outline package (SOT403-1), 16-pin, body width 4.4 mm, lead pitch 0.65 mm, exposed pad optional (non-electrical).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74AHCT138PW,118, the 74AHC138PW,118 delivers tighter input thresholds for modern CMOS systems and lower static current, while SN74LV138APWR trades minor speed loss for automotive compliance - making the original optimal for high-speed industrial control where qualification isn't mandated.

Availability

74AHC138PW,118 is available at Aetrix Electronics and suitable for memory decoding, industrial I/O expansion, LED multiplexing, and test equipment signal routing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74AHC138PW,118 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

Nexperia is a leading semiconductor manufacturer specializing in high-performance logic, analog, and discrete components, with core expertise in energy-efficient, high-reliability silicon solutions.

The 74AHC138PW,118 belongs to Nexperia's AHC logic family, designed for high-speed, low-power, mixed-voltage digital interfacing in industrial automation, communications infrastructure, and consumer electronics.

FAQ

Can 74AHC138PW,118 operate at 3.3 V supply with TTL-level inputs?

No - the 74AHC138PW,118 requires CMOS input levels (VIH ≥ 3.85 V at V_CC = 5.5 V). At 3.3 V V_CC, VIH is 2.1 V min, which may not reliably recognize standard 3.3 V TTL outputs (typically 2.4 V min). For guaranteed TTL compatibility, use the pin-compatible 74AHCT138PW,118 variant instead.

What is the maximum capacitive load each output can drive without exceeding timing specs?

The datasheet specifies timing parameters up to 50 pF load capacitance. Driving >50 pF increases propagation delay nonlinearly and may violate setup/hold windows in high-speed systems. For loads >50 pF, add a series resistor (22–47 Ω) near the output to damp ringing and maintain signal integrity.

Is the exposed pad on the TSSOP16 package electrically connected?

No - the exposed pad in SOT403-1 is a mechanical thermal enhancement feature only, with no electrical connection. Nexperia documentation explicitly states it has "no electrical or mechanical requirement to solder" and recommends leaving it floating or connecting to GND only if thermal simulation confirms benefit - never to V_CC.

How does the enable logic behave when E1 and E2 are tied together?

When E1 and E2 are shorted and driven by a single signal, the effective enable condition becomes (E1·E2·E3) = (E1)²·E3 = E1·E3, since E1 = E2. This reduces the enable flexibility but is functionally valid - however, it eliminates independent control of two enable paths needed for advanced cascading or power sequencing.