Nexperia USA Inc. 74HC238BQ,115

Overview

74HC238BQ,115 from Nexperia is a 3-to-8 line decoder/demultiplexer in DHVQFN16 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 2.0 V to 6.0 V, supports -40 °C to +125 °C ambient range, and is used in memory chip select decoding and address routing in microcontroller-based embedded systems.

For engineers reviewing the 74HC238BQ,115 datasheet, 74HC238BQ,115 pinout, 74HC238BQ,115 application, or 74HC238BQ,115 equivalent, key selection considerations include enable logic polarity (E1/E2 LOW + E3 HIGH), propagation delay (14–45 ns depending on VCC and input path), output drive capability (±4 mA at 4.5 V), CMOS-level input compatibility, and thermal-enhanced DHVQFN16 packaging for high-density PCB layouts.

Technical Context

The 74HC238BQ implements standard 3-bit binary decoding with strict mutual exclusivity: only one output goes HIGH per valid address/enable combination. Its triple-enable architecture (E1, E2, E3) enables cascading without external logic-four devices plus one inverter achieve 5-to-32 decoding. The device uses standard CMOS silicon with input clamp diodes enabling overvoltage-tolerant interfacing via current-limiting resistors.

Functional behavior is defined by a deterministic truth table where outputs remain LOW unless all three enables meet their logic conditions simultaneously. As a demultiplexer, it accepts data on an active-LOW enable (e.g., E1) while using A0–A2 and other enables as strobes-enabling flexible signal routing in bus-controlled systems.

Key Specifications

Pinout & Package

DHVQFN16 package (SOT763-1): 2.5 × 3.5 × 0.85 mm body, no leads, 16 terminals, exposed thermal pad (non-soldered or floating GND connection per datasheet).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HCT238BQ,115, the 74HC238BQ offers superior noise immunity in mixed-signal environments due to higher VIH, while SN74HC238PWR trades thermal efficiency for broader distributor availability and simpler assembly-but lacks the DHVQFN16's 0.85 mm height advantage in ultra-thin enclosures.

Availability

74HC238BQ,115 is available at Aetrix Electronics and suitable for memory decoding, microcontroller peripheral multiplexing, programmable logic interface, and industrial I/O expansion requiring stable component supply across automotive-adjacent, industrial control, and IoT edge device programs.

Supply support for 74HC238BQ,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, reliable components for automotive, industrial, mobile, and consumer electronics markets with focus on efficiency, reliability, and miniaturization.

The 74HC238BQ belongs to Nexperia's 74HC logic family-designed for low-power, high-noise-immunity digital interfacing in space-constrained embedded systems operating across extended temperature ranges.

FAQ

What is the maximum clock frequency supported by the 74HC238BQ,115 for address decoding?

The 74HC238BQ does not operate on a clock-it is combinational logic. Its usable address switching rate is governed by propagation delay: at VCC = 6.0 V and CL = 15 pF, tpd is 14 ns (typ), supporting reliable decoding of address changes up to ~35 MHz (1/2×tpd). System-level timing must account for worst-case 45 ns delay at VCC = 2.0 V.

Can the 74HC238BQ,115 be used as a demultiplexer, and how is the data input configured?

Yes. Configure any active-LOW enable input (E1 or E2) as the data input, hold the other two enables at fixed valid states (e.g., E2 = LOW, E3 = HIGH), and use A0–A2 as the 3-bit select lines. Data appears on the selected Yx output with the same propagation delay as address decoding-verified in Table 3 function table under "demultiplexing capability".

Is the exposed thermal pad on the DHVQFN16 package (SOT763-1) required to be soldered to ground?

No. Per datasheet section 5.1, the thermal pad (terminal 1) has no electrical or mechanical requirement to be soldered. If connected, it must remain floating or tied to GND-never left unconnected and floating, as that may cause EMI or thermal instability. Recommended practice is GND connection via thermal vias to inner ground planes.

How does the 74HC238BQ,115 handle input voltages exceeding VCC?

Inputs include integrated clamp diodes to VCC and GND. When VI exceeds VCC + 0.5 V, the upper clamp diode conducts-requiring an external current-limiting resistor (e.g., 1 kΩ) to restrict IIK to ≤±20 mA (absolute max). This allows safe interfacing with 5 V signals in 3.3 V systems without level shifters.