Texas Instruments CD74HC238M

Overview

CD74HC238M from Texas Instruments is a high-speed CMOS 3-to-8 line decoder/demultiplexer with active-high outputs, 16-pin SOIC package, -55°C to +125°C operating temperature range, 13 ns typical propagation delay at VCC = 5 V and CL = 15 pF, and 2 V to 6 V supply voltage support - used for memory address decoding and data routing in industrial control and instrumentation systems.

For engineers reviewing the CD74HC238M datasheet, CD74HC238M pinout, CD74HC238M application, or CD74HC238M equivalent, this page delivers verified functional behavior, exact pin roles, real-world use cases, and validated alternative options for system-level design and BOM optimization.

Technical Context

The CD74HC238M implements a 3-input address decoder with three enable inputs (G2, G1, G0) - one standard-active-high (G2) and two active-low (G1, G0) - enabling cascaded decoding and demultiplexing. When any strobe is asserted, all eight outputs (Y0–Y7) are driven low; otherwise, only the selected output is high per A2:A0 binary input.

It operates as a true HC-type device: rail-to-rail logic levels (VIH = 3.15 V min at VCC = 4.5 V), low static current (ICC ≤ 160 µA over full temp), and CMOS-compatible input leakage (II ≤ ±1 µA). Its output structure supports 4 mA sink/source drive capability with defined VOL/VOH across -55°C to +125°C.

Key Specifications

Pinout & Package

CD74HC238M is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm, with standard JEDEC MS-012AC footprint and gull-wing leads compatible with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC138M and SN74HC238N, the CD74HC238M offers native active-high outputs in a compact SOIC package - optimizing for SMT production, reduced component count, and compatibility with modern 3.3 V/5 V mixed-signal systems without level translation.

Availability

CD74HC238M is available at Aetrix Electronics and suitable for industrial control, test equipment, automotive diagnostics, and instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC238M 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The CD74HC238M belongs to TI's HC-series high-speed CMOS logic family, designed for low-power, high-noise-immunity digital interfacing in demanding environments where reliability and wide temperature operation are critical.

FAQ

What is the key functional difference between CD74HC238M and CD74HC138M?

The CD74HC238M features active-high outputs (Y0–Y7 go high when selected), while the CD74HC138M has active-low outputs (Y0–Y7 go low when selected). Both share identical pinout, timing, supply range, and enable architecture. This polarity difference eliminates external inverters when interfacing with logic that requires high-active enables - making CD74HC238M preferable in new designs targeting simplified signal routing and reduced component count.

Does CD74HC238M support 3.3 V operation?

Yes, CD74HC238M fully supports 3.3 V operation within its specified 2 V to 6 V supply range. At VCC = 3.3 V, VIH is guaranteed ≥ 2.31 V and VIL ≤ 1.1 V (30% hysteresis), ensuring reliable interfacing with 3.3 V microcontrollers and FPGAs without level-shifting circuitry - confirmed by TI's electrical characteristics tables across -55°C to +125°C.

Can CD74HC238M be used as a demultiplexer?

Yes, CD74HC238M functions as a 1-to-8 demultiplexer when G2 is used as the data input and A2:A0 as the channel select lines. When G2 is high and G0/G1 are low, the selected Yx output mirrors G2's state. This configuration is explicitly supported in TI's functional description and timing diagrams, enabling clean, low-glitch signal distribution in data acquisition and control systems.

What is the maximum output drive strength of CD74HC238M?

CD74HC238M delivers ±4 mA output drive at VCC = 4.5 V (per output), with VOL ≤ 0.4 V and VOH ≥ 3.7 V under those conditions. This meets LSTTL load requirements (10 LSTTL units) and supports direct connection to LEDs (with series resistor), small MOSFET gates, or other CMOS inputs - verified across the full -55°C to +125°C temperature range per TI's switching characteristics table.

Is CD74HC238M pin-compatible with CD74HC238E?

Yes, CD74HC238M (SOIC-16) and CD74HC238E (PDIP-16) share identical pin numbering, signal assignments, and electrical functionality. The only differences are package type (SOIC vs. PDIP), thermal performance (RθJA = 73°C/W vs. 67°C/W), and mounting method - allowing drop-in replacement in layout-constrained or through-hole designs, provided mechanical and thermal constraints are reviewed.