Nexperia USA Inc. 74AHCT138BQ-Q100X

Overview

74AHCT138BQ-Q100 from Nexperia is an automotive-grade 3-to-8 line inverting decoder/demultiplexer with TTL-compatible inputs, operating from 4.5 V to 5.5 V, featuring three enable inputs (two active LOW, one active HIGH), eight mutually exclusive active-LOW outputs (Y0–Y7), and qualified to AEC-Q100 Grade 1 (−40 °C to +125 °C) for use in engine control units and body electronics.

For engineers reviewing the 74AHCT138BQ-Q100 datasheet, 74AHCT138BQ-Q100 pinout, 74AHCT138BQ-Q100 application, or 74AHCT138BQ-Q100 equivalent, key selection considerations include its TTL-level input compatibility, propagation delay of ≤13.5 ns at 5 V/50 pF, DHVQFN16 package with side-wettable flanks for AOI, and multi-enable architecture enabling 1-of-32 expansion with minimal external logic.

Technical Context

This device implements a combinational logic decoder with fully static CMOS design, supporting both decoding (A0–A2 address mapping to Y0–Y7) and demultiplexing modes via enable-input reconfiguration. Its triple-enable structure (E1, E2 active LOW; E3 active HIGH) enables hierarchical cascading without additional gates.

All inputs feature Schmitt-trigger action for noise immunity, and outputs drive ±8 mA at VCC = 4.5 V while maintaining VOL ≤ 0.44 V and VOH ≥ 3.8 V across temperature. Input voltage tolerance exceeds VCC, allowing interfacing with higher-voltage logic domains.

Key Specifications

Pinout & Package

DHVQFN16 package (SOT763-1): 2.5 × 3.5 × 0.85 mm body, no leads, side-wettable flanks for automated optical inspection (AOI) of solder joints; thermal-enhanced construction supports sustained operation at full temperature range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74AHC138BQ-Q100 and SN74LS138DR, the 74AHCT138BQ-Q100 uniquely balances automotive qualification, TTL-level input compatibility, and sub-14 ns propagation delay-making it the sole option for production-grade 5 V automotive decoding where reliability and timing coexist.

Availability

74AHCT138BQ-Q100 is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS sensor interfaces, and infotainment systems requiring stable component supply across extended temperature ranges and automotive lifecycle commitments.

Supply support for 74AHCT138BQ-Q100 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 optimized for automotive, industrial, and consumer applications with emphasis on reliability and energy efficiency.

The 74AHCT138BQ-Q100 belongs to Nexperia's automotive-qualified logic family, engineered specifically for robust decoding and signal routing in harsh-temperature electronic control units where pin compatibility with legacy LSTTL and AEC-Q100 compliance are mandatory.

FAQ

What is the maximum clock/data rate supported by the 74AHCT138BQ-Q100?

The device is combinational (not clocked), so it has no clock input. Its maximum usable data rate depends on propagation delay and load capacitance. With CL = 50 pF and VCC = 5 V, tpd ≤ 13.5 ns supports address/data transitions up to ≈37 MHz in worst-case timing paths, assuming setup/hold margins are maintained by the driving controller.

Can unused enable inputs be left floating?

No. Unused enable inputs must be permanently tied to their defined active state: E1 and E2 to GND (active LOW), E3 to VCC (active HIGH). Floating enables risk metastability, increased ICC, or unintended output activation due to noise coupling in automotive EMI environments.

Is the thermal pad (Pin 1) required to be soldered to ground?

No. Pin 1 is a non-electrical thermal pad with no electrical function. Per Nexperia's datasheet, it may be left unsoldered, floated, or connected to GND - but if connected, the solder land must remain electrically isolated from other nets to avoid shorting internal die structures.

How does the 74AHCT138BQ-Q100 differ from the 74AHC138BQ-Q100 in system integration?

The 74AHCT138BQ-Q100 accepts standard TTL input thresholds (VIH = 2.0 V, VIL = 0.8 V), enabling direct connection to 5 V microcontrollers without level shifters. The 74AHC138BQ-Q100 requires CMOS-level inputs (VIH ≈ 3.85 V), necessitating voltage translation when driven by legacy 5 V TTL sources.