Nexperia USA Inc. 74HCT138D-Q100,118

Overview

74HCT138D-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, qualified per AEC-Q100 Grade 1 (−40 °C to +125 °C), and packaged in SO16 (SOT109-1). It decodes binary address inputs A0–A2 into eight mutually exclusive active-LOW outputs (Y0–Y7) under triple enable control (E1, E2 = LOW; E3 = HIGH), enabling memory chip select decoding in engine control units.

For engineers reviewing the 74HCT138D-Q100 datasheet, 74HCT138D-Q100 pinout, 74HCT138D-Q100 application, or 74HCT138D-Q100 equivalent, key selection criteria include its automotive temperature range, TTL-level input compatibility, propagation delay ≤53 ns at 5 V, active-LOW output polarity, and SO16 package suitability for high-reliability PCB assembly.

Technical Context

This device implements a combinational logic decoder with three independent enable inputs-two active-LOW (E1, E2) and one active-HIGH (E3)-requiring all three to be simultaneously asserted for any output activation. Its inverting architecture ensures only one output goes LOW per valid input combination, eliminating bus contention in memory addressing.

The 74HCT138D-Q100 uses standard CMOS silicon with TTL-input threshold levels (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 5 V), enabling direct interfacing with legacy 5 V TTL logic while maintaining low quiescent current (ICC ≤ 8 μA typ at 5.5 V) and high noise immunity (Δt/ΔV ≥ 139 ns/V).

Key Specifications

Pinout & Package

74HCT138D-Q100 is housed in a plastic small outline package (SO16, SOT109-1) with 16 leads, 3.9 mm body width, and gull-wing leads suitable for automated optical inspection and reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC138D-Q100, the 74HCT138D-Q100 offers tighter timing and guaranteed TTL compatibility at 5 V, while SN74LS138DR provides legacy pinout equivalence but fails automotive qualification and consumes >30× more quiescent power.

Availability

74HCT138D-Q100 is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS sensor hubs, and electric power steering systems requiring stable component supply across automotive production lifecycles.

Supply support for 74HCT138D-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 specializing in high-performance, high-reliability logic, analog, and MOSFET solutions, with core expertise in automotive-qualified components.

The 74HCT138D-Q100 belongs to Nexperia's automotive logic family, engineered specifically for robust address decoding and signal routing in harsh-temperature automotive subsystems where AEC-Q100 compliance and long-term supply stability are mandatory.

FAQ

Is the 74HCT138D-Q100 pin-compatible with standard 74LS138 or 74HC138 packages?

Yes - the 74HCT138D-Q100 uses the same SO16 (SOT109-1) footprint and pin assignment as industry-standard 74LS138 and 74HC138 devices, including identical A0–A2, E1–E3, Y0–Y7, VCC, and GND locations. This enables drop-in replacement in existing layouts, though electrical behavior (e.g., input thresholds, propagation delay) differs per logic family.

Can the 74HCT138D-Q100 be used as a demultiplexer, and how is that configured?

Yes - configure E3 as the data input (driven HIGH/LOW), and tie E1 and E2 to fixed logic levels (E1 = E2 = LOW) to enable the device. Address inputs A0–A2 then route the E3 signal to exactly one of Y0–Y7, with all other outputs remaining HIGH. This provides true 1-to-8 demux functionality without external gating.

What is the maximum clock frequency supported for address transitions?

The device has no internal clock; it is purely combinational. Maximum reliable address transition rate depends on propagation delay and system timing margins. With tpd ≤53 ns and tt ≤22 ns at 5 V, it supports address changes up to approximately 10 MHz in well-designed PCB layouts with proper decoupling and controlled impedance traces.

Does the 74HCT138D-Q100 support 3.3 V logic interfaces?

No - the 74HCT138D-Q100 is specified only for VCC = 4.5 V to 5.5 V and TTL-level inputs (VIH ≥ 2.0 V, VIL ≤ 0.8 V). Driving it from a 3.3 V MCU without level translation risks marginal VIH recognition and increased static current. For 3.3 V systems, use 74HC138D-Q100 or add a discrete level shifter.