Nexperia USA Inc. 74AHCT138PW-Q100J

Overview

74AHCT138PW-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, and qualification to AEC-Q100 Grade 1 for use in engine control units and body electronics.

For engineers reviewing the 74AHCT138PW-Q100 datasheet, 74AHCT138PW-Q100 pinout, 74AHCT138PW-Q100 application, or 74AHCT138PW-Q100 equivalent, key selection considerations include its TTL-level input compatibility, -40 °C to +125 °C operating range, propagation delay of 4.4 ns (typ) at 5 V/15 pF, demultiplexing capability via enable-input data routing, and TSSOP16 package with side-wettable flanks for AOI.

Technical Context

This device implements a combinational logic decoder with strict truth-table behavior: outputs Y0–Y7 go LOW only when E1 = LOW, E2 = LOW, and E3 = HIGH, while A0–A2 select exactly one output per binary input. All inputs feature Schmitt-trigger action for noise immunity.

It supports cascaded expansion to 1-of-32 decoding using four units and one inverter, and functions as an 8-output demultiplexer by assigning one active-LOW enable (e.g., E1) as the data input while strobing with E2/E3 - requiring unused enables to be hard-wired to valid logic states.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 4.4 mm body width, 0.65 mm lead pitch, side-wettable flanks for automated optical inspection of solder joints.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74AHC138PW-Q100, the AHCT variant offers guaranteed TTL input thresholds essential for robust 5 V system interoperability, while SN74LS138DR lacks automotive qualification and thermal performance - making 74AHCT138PW-Q100 the sole fit for new AEC-Q100-compliant designs requiring TTL compatibility.

Availability

74AHCT138PW-Q100 is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS sensor hubs, and infotainment display interfaces requiring stable component supply across automotive production lifecycles.

Supply support for 74AHCT138PW-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 leading semiconductor manufacturer specializing in high-performance, high-reliability logic, analog, and MOSFET solutions, with global R&D and manufacturing infrastructure focused on automotive and industrial markets.

The 74AHCT series targets automotive signal routing applications demanding AEC-Q100 qualification, TTL-level interoperability, and robust operation across extended temperature ranges - specifically designed for reliable decoding and demultiplexing in safety-critical vehicle subsystems.

FAQ

Can 74AHCT138PW-Q100 operate at 3.3 V supply?

No. The 74AHCT138PW-Q100 is specified only for 4.5 V to 5.5 V operation per Table 5. Its TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) are guaranteed within this range; operation below 4.5 V risks incorrect logic recognition and violates recommended conditions. For 3.3 V systems, use the 74AHC138PW-Q100 variant instead.

What is the maximum fan-out for Y0–Y7 outputs driving standard 74AHCT inputs?

Each output can drive up to 10 standard 74AHCT inputs. With IO = ±8 mA output drive and IIH/IIL ≤ 1 μA per 74AHCT input, the worst-case DC loading (10 × 1 μA = 10 μA) is well within the output's sourcing/sinking capability. AC loading depends on trace capacitance and switching frequency but remains viable up to 50 MHz with proper layout and termination.

Is the GND pad on the TSSOP16 package (Pin 8) thermally or electrically connected to the die paddle?

No. Pin 8 is the sole dedicated GND terminal and connects only to the internal ground bond wires. The exposed thermal pad on the underside of the SOT403-1 package (not assigned a pin number) is electrically isolated and intended solely for thermal conduction - it must remain floating or be connected to PCB GND via solder, per datasheet note in Section 5.1.

How does the device behave when E1 and E2 are HIGH but E3 is HIGH?

All outputs (Y0–Y7) remain HIGH regardless of A0–A2 state. The device requires E1 = LOW AND E2 = LOW AND E3 = HIGH for any output to go LOW. If either E1 or E2 is HIGH, the decoder is disabled and all outputs are forced HIGH - this is explicitly defined in Table 3 (Function table) under "X H X" and "H X X" input combinations.