Nexperia USA Inc. 74HCT238PW,118

Overview

74HCT238PW,118 from Nexperia is a 3-to-8 line decoder/demultiplexer in TSSOP16 package, featuring three binary address inputs (A0–A2), eight active-HIGH mutually exclusive outputs (Y0–Y7), and three enable inputs (E1, E2 active LOW; E3 active HIGH) for parallel expansion to 1-of-32 decoding. It operates from 4.5 V to 5.5 V, supports -40 °C to +125 °C ambient range, and is used in memory chip select logic and address decoding in industrial microcontroller systems.

For engineers reviewing the 74HCT238PW,118 datasheet, 74HCT238PW,118 pinout, 74HCT238PW,118 application, or 74HCT238PW,118 equivalent, key selection criteria include TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 5 V), propagation delay of 19–53 ns across temperature, output drive capability of ±4 mA, and compatibility with 15 pF load capacitance in standard timing-critical digital control paths.

Technical Context

The 74HCT238PW,118 implements a combinational logic decoder with synchronous enable gating: all outputs remain LOW unless E1 = LOW, E2 = LOW, and E3 = HIGH - enabling precise hierarchical addressing in multi-chip memory or peripheral selection. Its TTL-level input interface ensures direct compatibility with legacy 5 V logic families without level-shifting.

It supports demultiplexing by repurposing one enable input (e.g., E1) as data input while using A0–A2 and remaining enables as address/strobe controls. Input clamp diodes allow safe interfacing to voltages exceeding VCC when current-limiting resistors are applied - critical for mixed-voltage board designs.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1): plastic thin shrink small outline, 16 leads, body width 4.4 mm, 0.65 mm pitch, exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT138DR and 74LVC138APW,118, the 74HCT238PW,118 uniquely delivers active-HIGH outputs with native 5 V TTL input compatibility and extended industrial temperature support - making it optimal for legacy-compatible, high-reliability 5 V decoding where output polarity and voltage robustness are non-negotiable.

Availability

74HCT238PW,118 is available at Aetrix Electronics and suitable for memory address decoding, peripheral multiplexing, LED display control, and test signal routing requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for 74HCT238PW,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 automotive-qualified and industrial-grade standard products.

The 74HCT238PW,118 belongs to Nexperia's 74HCT logic family, engineered for TTL-compatible operation in 5 V systems with emphasis on noise immunity, wide temperature operation, and reliability in harsh industrial environments.

FAQ

What is the maximum clock or address transition rate supported by the 74HCT238PW,118?

The device has no internal clock; its speed is governed by input transition rates. Per datasheet Table 5, Δt/ΔV must be ≥83 ns/V at VCC = 6.0 V, translating to a practical maximum input edge rate of ~12 MHz for clean signal integrity. For reliable operation with 5 V supplies, rise/fall times should stay below 15 ns to avoid metastability in enable/address sampling windows.

Can the 74HCT238PW,118 be used in a 3.3 V system?

No - the 74HCT238PW,118 is specified only for 4.5 V to 5.5 V operation. At 3.3 V, input thresholds (VIH ≥ 2.0 V) become marginal, and static characteristics like VOH degrade significantly. Use 74LVC138APW,118 instead for 3.3 V systems, or add level-shifting circuitry if interfacing with 3.3 V controllers.

How does the enable logic prevent partial output activation during power-up?

The triple-enable requirement (E1 = LOW, E2 = LOW, E3 = HIGH) creates a fail-safe default state: all outputs remain LOW until all three enables settle. Internal power-on reset is not present, but the combinational logic ensures no Yx asserts unless all enable conditions are simultaneously met - eliminating glitches during VCC ramp-up when enables stabilize at different rates.

Is the exposed pad on the TSSOP16 package electrically connected?

No - the exposed pad in SOT403-1 (TSSOP16) is a mechanical thermal enhancement feature only. Per datasheet Section 5.1 and Figure 8, it has no electrical function and must remain floating or be connected to GND solely for thermal conduction; soldering it to GND introduces no electrical benefit or risk if done correctly.