Nexperia USA Inc. 74HCT138D,652

Overview

74HCT138D,652 from Nexperia is a 3-to-8 line inverting decoder/demultiplexer with TTL-compatible inputs, operating from 4.5 V to 5.5 V, featuring three enable inputs (E1, E2 active LOW; E3 active HIGH), eight mutually exclusive active LOW outputs (Y0–Y7), and SO16 (SOT109-1) package for memory chip select decoding in industrial microcontroller systems.

For engineers reviewing the 74HCT138D,652 datasheet, 74HCT138D,652 pinout, 74HCT138D,652 application, or 74HCT138D,652 equivalent, key selection considerations include TTL-level input compatibility, propagation delay ≤44 ns at 5 V/50 pF, -40 °C to +125 °C operation, and parallel expansion capability for 1-of-32 decoding using four ICs and one inverter.

Technical Context

The 74HCT138D,652 implements combinational logic decoding of three binary address inputs (A0–A2) into eight unique active LOW outputs, with strict mutual exclusivity enforced by the triple-enable architecture (E1=E2=LOW, E3=HIGH). Its TTL-input thresholds (VIH ≥2.0 V, VIL ≤0.8 V at VCC = 5 V) ensure direct interfacing with legacy 5 V logic families without level shifting.

Propagation delays are asymmetric across control paths: A-input-to-Y delay is ≤44 ns, while E3-to-Y and E1/E2-to-Y delays are ≤60 ns under identical conditions (VCC = 5 V, CL = 50 pF). The device lacks 3-state outputs and relies on open-drain-compatible active LOW outputs for wired-OR bus arbitration in chip select trees.

Key Specifications

Pinout & Package

74HCT138D,652 uses the SO16 plastic small outline package (SOT109-1), 16-pin, 3.9 mm body width, with gull-wing leads and pin 1 index marker. Thermal resistance θJA = 110 K/W; Ptot derates linearly at 12.4 mW/K above 110 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT138DR, the 74HCT138D,652 offers guaranteed +125 °C operation critical for harsh environments; versus 74HC138D,653, it provides seamless TTL interoperability at the cost of slightly higher tpd - making it the optimal choice for mixed-signal industrial controllers.

Availability

74HCT138D,652 is available at Aetrix Electronics and suitable for memory decoding, peripheral selection, LED multiplexing, and test signal routing requiring stable component supply across industrial temperature grades and long-lifecycle programs.

Supply support for 74HCT138D,652 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 logic, discrete, and MOSFET solutions optimized for efficiency and miniaturization in industrial, automotive, and consumer applications.

The 74HCT138D,652 belongs to Nexperia's 74HCT logic family, engineered specifically for robust TTL-to-CMOS interfacing in noise-prone industrial control systems where wide voltage margins and extended temperature operation are mandatory.

FAQ

Can 74HCT138D,652 be used with 3.3 V microcontrollers?

No - the 74HCT138D,652 requires VCC = 4.5 V to 5.5 V and has TTL input thresholds (VIH ≥2.0 V minimum). A 3.3 V MCU cannot reliably drive its inputs without external level-shifting circuitry, as its VOH (typically ~3.0 V) falls below the required VIH at VCC = 5 V. Use 74LVC138 or 74AUP138 for native 3.3 V compatibility.

What is the maximum fan-out when driving other 74HCT inputs?

At VCC = 5 V and Tamb = 25 °C, the 74HCT138D,652 can drive up to 10 standard 74HCT inputs (each drawing ≤1 μA IIH) due to its VOH ≥3.98 V at IO = −4 mA and VOL ≤0.26 V at IO = 4 mA. Fan-out drops to ≤6 at +125 °C due to increased VOL (≤0.4 V) and reduced VOH (≥3.7 V).

Is the SO16 package RoHS-compliant and lead-free?

Yes - the 74HCT138D,652 in SOT109-1 (SO16) package is fully RoHS-compliant and lead-free per Nexperia's product compliance documentation (document ID: "74HC_HCT138" Rev. 10, Section 14). It meets JEDEC J-STD-609 Category 1 marking requirements and has no exemptions for lead content.

How does the enable logic prevent partial output activation?

The 74HCT138D,652 uses strict AND-logic across all three enables: outputs are HIGH (inactive) unless E1 = LOW, E2 = LOW, and E3 = HIGH simultaneously. This prevents glitches during enable sequencing - e.g., if E3 transitions before E1/E2 settle, all outputs remain HIGH, avoiding spurious chip selects or peripheral enables.