Nexperia USA Inc. 74HCT238D,652

Overview

74HCT238D,652 from Nexperia is a 3-to-8 line decoder/demultiplexer in SO16 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 TTL-level inputs, and is rated for -40 °C to +125 °C - used in memory chip select decoding and address routing in industrial microcontroller systems.

For engineers reviewing the 74HCT238D,652 datasheet, 74HCT238D,652 pinout, 74HCT238D,652 application, or 74HCT238D,652 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, SO16 pin mapping with GND on pin 8 and VCC on pin 16, and functional equivalence to 74HCT138 with expanded enable logic.

Technical Context

The 74HCT238D implements combinational logic decoding with strict mutual exclusivity: only one output goes HIGH when all enables are satisfied (E1 = LOW, E2 = LOW, E3 = HIGH) and a unique 3-bit address is applied. Its enable architecture allows cascading via inverted E3 to build larger decoders without external logic.

Input clamping diodes permit interfacing with voltages exceeding VCC when current-limiting resistors are used. Static characteristics confirm TTL-compatible VIH/VIL thresholds and rail-to-rail VOH/VOL performance under ±4 mA loads at 5 V, ensuring robust noise immunity and compatibility with legacy 5 V logic families.

Key Specifications

Pinout & Package

74HCT238D,652 uses the SO16 (SOT109-1) plastic small outline package: 16-pin, 3.9 mm body width, 1.27 mm lead pitch, gull-wing leads, JEDEC MS-012 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HCT138D,653, the 74HCT238D,652 offers superior expandability via its native three-enable structure, while SN74HCT238N trades surface-mount reliability for hand-soldering convenience - making the SO16 variant optimal for high-density, automated industrial PCBs.

Availability

74HCT238D,652 is available at Aetrix Electronics and suitable for memory decoding, microcontroller peripheral selection, LED multiplexing, and automated test equipment requiring stable component supply across extended temperature ranges.

Supply support for 74HCT238D,652 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 logic, analog, and MOSFET solutions with focus on efficiency, miniaturization, and robustness for industrial and automotive markets.

The 74HCT238 belongs to Nexperia's high-speed TTL-compatible logic family, designed specifically for noise-immune address decoding and signal routing in resource-constrained embedded systems operating across harsh thermal environments.

FAQ

What is the function of the E1, E2, and E3 enable inputs on the 74HCT238D,652?

E1 and E2 are active-LOW enables; E3 is active-HIGH. All three must be simultaneously asserted (E1 = LOW, E2 = LOW, E3 = HIGH) for the decoder to respond to address inputs A0–A2. This triple-enable structure allows hierarchical system partitioning and direct 1-of-32 expansion using four '238 ICs and one inverter - no additional logic required.

Can the 74HCT238D,652 be used as a demultiplexer, and how?

Yes - configure one enable input (e.g., E1) as the data input (LOW = data '0', HIGH = data '1') and use A0–A2 as the 3-bit channel select. With E2 held LOW and E3 held HIGH, the data appears inverted on the selected Yx output. This provides true 1-to-8 demux functionality with sub-53 ns switching and TTL-compatible control timing.

How does the 74HCT238D,652 differ from the 74HCT138 in practical design?

The 74HCT238D,652 replaces the 74HCT138's single active-LOW strobe (G1) and dual active-LOW enables (G2A/G2B) with three independent enables (E1/E2 LOW, E3 HIGH), enabling more flexible cascading without external inverters. Its pinout differs: Y0–Y7 occupy pins 15–7 (vs. 1–7, 15 on '138), and E3 is on pin 6 instead of G1 on pin 1 - requiring PCB layout revision.

Is the 74HCT238D,652 suitable for automotive applications?

No - although rated for -40 °C to +125 °C, this device is not AEC-Q100 qualified and lacks automotive-specific validation (e.g., HTOL, ESD stress beyond HBM 2 kV). Nexperia explicitly states non-automotive qualification in its legal disclaimers; use only in industrial, commercial, or consumer systems where automotive-grade reliability is not mandated.