Texas Instruments CD74HCT154ENG4

Overview

CD74HCT154ENG4 from Texas Instruments is a 4-to-16-line decoder/demultiplexer with dual enable inputs (E1, E2), operating at 4.5V–5.5V, delivering 35ns typical propagation delay (CL = 50pF, TA = 25°C), 15 LSTTL fanout, and full -55°C to +125°C industrial/military temperature range - used in address decoding for memory expansion and I/O port selection in embedded control systems.

For engineers reviewing the CD74HCT154ENG4 datasheet, CD74HCT154ENG4 pinout, CD74HCT154ENG4 application, or CD74HCT154ENG4 equivalent, this page delivers verified functional identity, validated 24-pin PDIP package mapping, confirmed HCT logic family behavior, real-world demultiplexing use cases, and two technically documented alternative parts with explicit interface and timing differences.

Technical Context

The CD74HCT154ENG4 implements active-low 4-bit binary decoding with two independent enable inputs: a high on either E1 or E2 forces all 16 outputs (Y0–Y15) high; only when both enables are low does the A0–A3 address bus select one active-low output. Its architecture supports cascading via enable chaining and demultiplexing by routing data through one enable while holding the other low.

It uses CMOS process technology with TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V at VCC = 4.5–5.5 V), guarantees 0.1 V max VOL under 4 mA load, and maintains balanced tPLH/tPHL transition symmetry across all outputs - critical for synchronous address decoding in multi-chip systems.

Key Specifications

Pinout & Package

CD74HCT154ENG4 is housed in a 24-lead plastic dual-in-line package (PDIP), 0.300-inch body width, with standard through-hole mounting and JEDEC MS-001AC footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-to-16 decoder/demultiplexer applications.

Compared with CD74HCT154ENG4, SN74HCT154N trades military-grade temperature range for lower cost and power, while CD74HC154EN sacrifices TTL input compatibility for wider voltage operation and reduced static current - neither is pin- or functionally identical without verifying system-level voltage and timing margins.

Availability

CD74HCT154ENG4 is available at Aetrix Electronics and suitable for memory address decoding, I/O port expansion, industrial PLC backplanes, and aerospace avionics subsystems requiring stable component supply across extended temperature and long lifecycle support.

Supply support for CD74HCT154ENG4 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

Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and defense qualification.

CD74HCT154ENG4 belongs to TI's High-Speed CMOS Logic (HCT) product line, engineered specifically for drop-in replacement of legacy LSTTL logic in 5 V systems while delivering CMOS-level power efficiency and noise resilience.

FAQ

What is the exact function of CD74HCT154ENG4 in a digital system?

The CD74HCT154ENG4 functions as a 4-to-16 line decoder/demultiplexer with dual active-low enable inputs. It accepts four binary address inputs (A0–A3) and asserts exactly one of sixteen active-low outputs (Y0–Y15) when both enables (E1 and E2) are low; otherwise, all outputs remain high. This behavior is used for memory chip selection, I/O device addressing, and signal routing in microprocessor and microcontroller systems. The CD74HCT154ENG4 implements this logic with TTL-compatible input thresholds and CMOS output drive.

Does CD74HCT154ENG4 support 3.3 V logic interfaces?

No, CD74HCT154ENG4 does not support 3.3 V logic interfaces. Its HCT family specification mandates a supply voltage range of 4.5 V to 5.5 V and defines input thresholds relative to 5 V operation (VIH ≥ 2.0 V, VIL ≤ 0.8 V). Driving it with 3.3 V logic may result in unreliable recognition of high-level inputs due to insufficient VIH margin. For 3.3 V systems, consider logic-level translators or HC-family variants like CD74HC154EN with appropriate supply and interface conditioning.

Can CD74HCT154ENG4 be used for demultiplexing data signals?

Yes, CD74HCT154ENG4 can perform demultiplexing: configure one enable input (e.g., E1) as the data input, hold the other enable (E2) low, and use A0–A3 to select which of Y0–Y15 receives the inverted data signal. Since all outputs are active-low, the selected line mirrors the logical inverse of E1. This mode is explicitly described in the datasheet's functional description and truth table, and is commonly applied in serial-to-parallel conversion and peripheral selection circuits using the CD74HCT154ENG4.

What is the maximum clock/data rate compatible with CD74HCT154ENG4?

The CD74HCT154ENG4 is not a clocked device and has no internal clock; its speed is governed by propagation delay and transition times. With 35 ns typical address-to-output delay (CL = 50 pF, VCC = 4.5 V, 25°C) and 15 ns typical output transition time, it supports reliable operation with address changes up to approximately 10 MHz in well-decoupled, low-capacitance layouts. System-level timing must account for worst-case 53 ns delay over full temperature range and loading - the CD74HCT154ENG4 is suited for asynchronous decoding, not high-speed synchronous buses.

Is CD74HCT154ENG4 RoHS compliant and lead-free?

Yes, CD74HCT154ENG4 is RoHS compliant and lead-free. Per Texas Instruments' packaging documentation, the "G4" suffix denotes lead-free finish (NiPdAu), and the part carries Level-1 MSL rating with peak reflow tolerance of 260°C. The PDIP package uses matte tin lead finish, fully compliant with EU RoHS Directive 2011/65/EU and JEDEC J-STD-020. Traceability and compliance documentation for CD74HCT154ENG4 is available through TI's Quality & Environmental portal.