Nexperia USA Inc. 74AHC138D,118

Overview

74AHC138D,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 supply voltage range 2.0–5.5 V. It is widely used for memory chip select decoding in industrial microcontroller systems.

For engineers reviewing the 74AHC138D,118 datasheet, 74AHC138D,118 pinout, 74AHC138D,118 application, or 74AHC138D,118 equivalent, key selection considerations include propagation delay (4.4 ns typ @ 5 V, 15 pF), CMOS-level input compatibility, SO16 package thermal performance, and multi-enable expansion capability for 1-of-32 decoding.

Technical Context

The device implements a fully decoded 3-bit binary input logic with active-low outputs, where only one Yn output goes LOW when all enables are satisfied (E1 = E2 = LOW, E3 = HIGH). Its Schmitt-trigger inputs provide noise immunity on address and enable lines, supporting reliable operation in electrically noisy embedded environments.

Multiple enable architecture allows cascading-e.g., four 74AHC138D units plus one inverter implement a 5-to-32 decoder without external logic. As a demultiplexer, any active-low enable (e.g., E1) serves as data input while others act as strobes, enabling flexible signal routing in bus arbitration and peripheral selection circuits.

Key Specifications

Pinout & Package

74AHC138D,118 is housed in a plastic small outline package (SO16, SOT109-1) with 16 leads, 3.9 mm body width, and standard 1.27 mm lead pitch. The package supports reflow soldering per JEDEC J-STD-020 and provides adequate thermal dissipation (Ptot = 500 mW at Tamb ≤ 110 °C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74AHCT138D,118, the 74AHC138D,118 offers superior noise immunity and 3.3 V compatibility, while SN74LV138APWR trades speed for quiescent current reduction - making each optimal for distinct voltage, speed, and power constraints.

Availability

74AHC138D,118 is available at Aetrix Electronics and suitable for memory decoding, peripheral multiplexing, bus arbitration, and digital display control requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for 74AHC138D,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 global semiconductor expert delivering high-performance, reliable, and efficient logic, analog, and discrete components, with leadership in automotive-grade and industrial-standard logic families.

The 74AHC series targets high-speed, low-power CMOS logic applications in industrial, computing, and communications equipment, emphasizing pin compatibility, wide supply range, and robust ESD tolerance.

FAQ

What is the maximum clock frequency supported by the 74AHC138D,118 for address decoding?

The 74AHC138D,118 does not operate on a clock; it is combinational logic. Its usable frequency limit is determined by propagation delay and system timing margins. With tpd = 4.4 ns (typ) at 5 V, it supports address changes up to ~100 MHz in systems where setup/hold times allow - verified across -40 °C to +125 °C per JEDEC JESD78.

Can the 74AHC138D,118 be used with a 3.3 V supply and 5 V-tolerant inputs?

Yes. The device accepts input voltages up to 5.5 V regardless of VCC (2.0–5.5 V), enabling direct connection to 5 V address buses while powered from 3.3 V. This is explicitly specified in Table 5 (VI input voltage) and confirmed in Section 2's "Inputs accepts voltages higher than VCC" feature.

How should unused enable inputs be terminated?

Unused enable inputs must be permanently tied to their active state: E1 and E2 to GND (LOW), E3 to VCC (HIGH). Floating enables risk metastability and increased ICC due to input stage oscillation - confirmed in Section 1's General Description and Table 3's function table.

Is the SO16 package (SOT109-1) RoHS compliant and lead-free?

Yes. Nexperia confirms the 74AHC138D,118 in SO16 packaging meets RoHS Directive 2011/65/EU and is lead-free, with matte tin (Sn) termination finish. This is documented in Nexperia's official compliance statements and product change notices dated 2023 onward.