Nexperia USA Inc. 74HCT238BQ,115

Overview

74HCT238BQ,115 from Nexperia is a 3-to-8 line decoder/demultiplexer IC with TTL-compatible inputs, active-HIGH mutually exclusive outputs (Y0–Y7), three enable inputs (E1, E2 active LOW; E3 active HIGH), and operation across 4.5 V to 5.5 V supply. It supports memory chip select decoding and parallel expansion to 1-of-32 decoding using four units and one inverter. Designed for industrial embedded control systems requiring precise address decoding at -40 °C to +125 °C.

For engineers reviewing the 74HCT238BQ,115 datasheet, 74HCT238BQ,115 pinout, 74HCT238BQ,115 application, or 74HCT238BQ,115 equivalent, key selection criteria include TTL-level input compatibility, propagation delay under 53 ns at 5 V, DHVQFN16 thermal-enhanced packaging, and guaranteed operation over extended temperature range without derating.

Technical Context

The 74HCT238BQ implements combinational logic decoding of three binary address inputs (A0–A2) into eight fully decoded, mutually exclusive outputs-each asserted LOW only when all enables satisfy E1 = LOW, E2 = LOW, and E3 = HIGH. Its enable architecture allows cascading via shared strobes and direct demultiplexing by routing data through an enable input.

Input clamping diodes permit safe interfacing to voltages exceeding VCC when used with current-limiting resistors. The device complies with JEDEC JESD7A (2.0–6.0 V) and JESD8C (2.7–3.6 V), and exhibits latch-up immunity >100 mA per JESD78 Class II Level B.

Key Specifications

Pinout & Package

DHVQFN16 package (SOT763-1): 2.5 mm × 3.5 mm × 0.85 mm body, no leads, thermally enhanced exposed pad (non-soldered or GND-connected), 16 terminals, pin 1 index marked on top surface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC238BQ,115 and SN74LS238N, the 74HCT238BQ,115 uniquely balances TTL input compatibility, QFN thermal performance, and industrial temperature support-making it optimal for new surface-mount designs requiring robust 5 V logic interfacing without redesigning level-shifting networks.

Availability

74HCT238BQ,115 is available at Aetrix Electronics and suitable for memory decoding, peripheral multiplexing, industrial I/O expansion, and automotive subsystem enable applications requiring stable component supply across extended temperature ranges and high-volume production cycles.

Supply support for 74HCT238BQ,115 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 logic, analog, and MOSFET solutions with focus on efficiency, reliability, and miniaturization for industrial, automotive, and computing markets.

The 74HCT238BQ,115 belongs to Nexperia's 74HCT logic family-designed specifically for seamless integration between TTL-based microcontrollers and CMOS peripherals while maintaining low power and high noise immunity in harsh environments.

FAQ

Can the 74HCT238BQ,115 operate at 3.3 V?

No. The 74HCT238BQ,115 is specified only for 4.5 V to 5.5 V supply per JEDEC JESD8C. At 3.3 V, input thresholds fall outside TTL compatibility range and VOH/VOL degrade beyond specification-use 74HC238BQ,115 instead for 2.0–6.0 V operation including 3.3 V systems.

Is the exposed thermal pad on the DHVQFN package required to be soldered?

No. Per Nexperia SOT763-1 datasheet, the exposed pad (terminal 1 index area) has no electrical or mechanical requirement to be soldered. If soldered, it must remain floating or connect to GND-never to VCC or signal nets-to avoid thermal stress or short circuits.

How does the 74HCT238BQ,115 differ from standard 74HCT138 variants?

The 74HCT238BQ,115 uses identical pinout and logic function as 74HCT138 but features improved ESD ratings (HBM > 2000 V), tighter propagation delay consistency (±5 ns typical variation), and enhanced latch-up immunity (>100 mA). It also supports full −40 °C to +125 °C operation without derating, unlike some 138 variants rated only to +85 °C.

What is the maximum capacitive load the 74HCT238BQ,115 can drive reliably?

The device is characterized up to 50 pF load capacitance (per Table 9 test conditions) with guaranteed t_pd and t_t. Driving >50 pF may increase propagation delay nonlinearly and risk output ringing; for >100 pF loads, add series termination or buffer stages to maintain signal integrity and timing margins.