Texas Instruments CD74HCT238PW

Overview

CD74HCT238PW 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 temperature range, and features three enable inputs (G2, G1, G0) for cascading.

For engineers reviewing the CD74HCT238PW datasheet, CD74HCT238PW pinout, CD74HCT238PW application, or CD74HCT238PW equivalent, this page provides verified functional behavior, TSSOP-16 package details, output polarity confirmation (active-high Y0–Y7), LSTTL-compatible input thresholds, and real-world demultiplexing use cases - all grounded in TI's SCHS147J datasheet.

Technical Context

The CD74HCT238PW implements a single 3:8 decoder with three address inputs (A0–A2) and three strobe enables (G2, G1, G0). When enabled, exactly one of eight outputs goes high per binary address; when any strobe is asserted, all outputs force low - enabling precise demultiplexing and hierarchical decoding.

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_I ≤ 1 µA) and noise immunity (NIL/NIH = 30% of V_CC). Propagation delay and transition times are balanced across temperature extremes (-55°C to 125°C).

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm body size), lead-free (NIPDAU/SN), moisture sensitivity level 1, RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HCT138PW, the CD74HCT238PW eliminates external inversion for high-enable loads; compared with SN74HCT238PWR, it shares identical silicon and performance but differs only in orderable packaging configuration and lifecycle status (CD74HCT238PW is obsolete, PWR is active).

Availability

CD74HCT238PW is available at Aetrix Electronics and suitable for industrial control, automotive sensor interfaces, and test equipment requiring stable component supply and extended temperature support.

Supply support for CD74HCT238PW 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 specializing in analog, embedded processing, and logic solutions, with over 90 years of innovation in high-reliability components.

The CD74HCT238PW belongs to TI's CD74HCT logic family, engineered for robust 5 V system interfacing in industrial, aerospace, and automotive applications where LSTTL compatibility and wide temperature operation are essential.

FAQ

What is the output behavior of CD74HCT238PW when all enable inputs are asserted?

When G2 is HIGH and both G1 and G0 are LOW, the CD74HCT238PW operates normally: one output (Y0–Y7) goes HIGH according to the A2–A0 address, while all others remain LOW. If any enable condition fails (e.g., G2 = LOW or G1 = HIGH), all outputs force LOW - confirmed in Table 7-2 of TI's SCHS147J datasheet for CD74HCT238PW.

Does CD74HCT238PW support 3.3 V logic inputs?

No. CD74HCT238PW is an HCT-family device with LSTTL-compatible input thresholds: V_IL ≤ 0.8 V (max) and V_IH ≥ 2.0 V (min) at V_CC = 4.5–5.5 V. A 3.3 V logic HIGH may not reliably meet the 2.0 V minimum V_IH, risking metastability; use CD74HC238PW for 3.3 V systems.

Can CD74HCT238PW be used as a demultiplexer?

Yes. The CD74HCT238PW functions as a 1-to-8 demultiplexer when G2 is used as the data input and A0–A2 as the channel select lines. With G1 and G0 held inactive (G1 = HIGH, G0 = HIGH), the selected Yx output mirrors G2's state - a documented mode in TI's "Detailed Description" section (7.1) for CD74HCT238PW.

What is the maximum output current per pin for CD74HCT238PW?

The CD74HCT238PW supports ±4 mA DC output current per Yx pin (I_OL/I_OH) at V_CC = 4.5 V, as specified in Section 5.4 ("Electrical Characteristics") of the datasheet. Exceeding this may cause VOL > 0.4 V or VOH < 3.7 V, violating logic thresholds.

Is CD74HCT238PW pin-compatible with CD74HC238PW?

Yes - CD74HCT238PW and CD74HC238PW share identical TSSOP-16 pinout, terminal functions, and package dimensions. However, they differ in logic family: HC operates from 2–6 V with CMOS inputs, while HCT requires 4.5–5.5 V and accepts LSTTL inputs. Substitution requires verifying supply voltage and source logic levels.