Texas Instruments CD74HCT238M96

Overview

CD74HCT238M96 from Texas Instruments is a high-speed CMOS 3-to-8 line decoder/demultiplexer with active-high outputs, designed for memory address decoding and data routing in industrial control and embedded systems. It operates at 4.5–5.5 V, delivers 14 ns typical propagation delay (V_CC = 4.5 V, C_L = 15 pF), supports -55°C to +125°C operation, and features three enable inputs (G2, G1, G0) for cascading.

For engineers reviewing the CD74HCT238M96 datasheet, CD74HCT238M96 pinout, CD74HCT238M96 application, or CD74HCT238M96 equivalent, this page provides verified functional behavior, exact SOIC-16 pin mapping, temperature-rated switching characteristics, LSTTL-compatible input thresholds, and real-world demultiplexing use cases - all confirmed against TI's SCHS147J revision J datasheet.

Technical Context

The CD74HCT238M96 implements a 3-input address decoder (A2–A0) with three independent strobe enables: G2 (active-high), G1 and G0 (both active-low). When any strobe is asserted, all eight outputs (Y0–Y7) are driven low - distinguishing it from the '138 family's active-low output behavior.

Its HCT logic family ensures direct compatibility with LSTTL inputs (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), while maintaining CMOS power efficiency (I_CC ≤ 160 µA over full temperature range) and robust noise immunity (NIL/NIH = 30% of V_CC).

Key Specifications

Pinout & Package

CD74HCT238M96 is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm, with standard 1.27 mm pitch and RoHS-compliant NIPDAU/SN lead finish (MSL Level-1).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HCT138M96, the CD74HCT238M96 provides native active-high outputs - eliminating board-level inversion and reducing BOM count. Against SN74HCT138DR, it shares identical functionality but reflects earlier TI production lineage; both meet the same HCT specification and operate across –55°C to +125°C.

Availability

CD74HCT238M96 is available at Aetrix Electronics and suitable for industrial control, automotive body electronics, test equipment signal routing, and high-reliability embedded systems requiring stable component supply across extended temperature ranges.

Supply support for CD74HCT238M96 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 CD74HCT238M96 belongs to TI's legacy high-speed CMOS logic family, engineered for robust 5 V system interfacing, wide-temperature reliability, and seamless integration into memory-mapped and demultiplexing architectures.

FAQ

What is the maximum operating frequency supported by the CD74HCT238M96?

The CD74HCT238M96 does not specify a maximum clock frequency, as it is a combinational logic device. Its usable switching speed is determined by propagation delay: 14 ns typical (V_CC = 4.5 V, C_L = 15 pF), supporting reliable operation up to approximately 35 MHz in cascaded decode paths. For precise timing analysis, refer to the t_pd and t_t values in Section 5.5 of the CD74HCT238M96 datasheet.

Can CD74HCT238M96 be used as a demultiplexer, and how is that configured?

Yes, the CD74HCT238M96 functions as a 1-to-8 demultiplexer. Configure it by applying the data signal to one of the enable inputs (typically G2), and using A2–A0 as the 3-bit channel select. When G2 is high and G1/G0 are low, the data appears inverted on the selected Yx output due to the active-high architecture - making it ideal for enabling downstream logic or driving active-high peripherals.

Does CD74HCT238M96 require external pull-up resistors on its outputs?

No, the CD74HCT238M96 features push-pull outputs capable of sourcing up to 4 mA and sinking up to 4 mA. External pull-ups are unnecessary unless interfacing with open-drain buses or implementing wired-OR logic. The outputs drive cleanly to VOH ≥ 3.98 V and VOL ≤ 0.4 V under full load, per CD74HCT238M96's electrical characteristics table.

How does the enable logic of CD74HCT238M96 differ from CD74HC238M96?

The CD74HCT238M96 and CD74HC238M96 share identical enable structure (G2 active-high, G1/G0 active-low) and truth table. The key difference lies in input compatibility: CD74HCT238M96 accepts LSTTL voltage levels (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), while CD74HC238M96 requires CMOS thresholds (V_IL ≤ 1.35 V, V_IH ≥ 3.15 V at V_CC = 4.5 V). This makes CD74HCT238M96 the correct choice for mixed-logic systems with TTL sources.

Is CD74HCT238M96 pin-compatible with CD74HCT138M96?

Yes, CD74HCT238M96 is fully pin-compatible with CD74HCT138M96 in the same SOIC-16 package. Both share identical pinout, supply requirements, and enable input behavior. The only functional difference is output polarity: CD74HCT238M96 outputs go high when selected, whereas CD74HCT138M96 outputs go low. Swapping them requires verifying downstream logic polarity tolerance.