Texas Instruments SN74LVC138ADT

Overview

SN74LVC138ADT from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in SOIC-16 package, operating from 1.65 V to 3.6 V with 5.8 ns max propagation delay at 3.3 V. It features three binary select inputs (A, B, C), two active-low enables (G2A, G2B), one active-high enable (G1), and eight active-low outputs (Y0–Y7). It is used for memory decoding and LED matrix column selection in industrial control systems.

For engineers reviewing the SN74LVC138ADT datasheet, SN74LVC138ADT pinout, SN74LVC138ADT application, or SN74LVC138ADT equivalent, key selection criteria include supply voltage range (1.65–3.6 V), input tolerance up to 5.5 V, propagation delay performance, enable logic configuration, and SOIC-16 thermal and layout compatibility.

Technical Context

The SN74LVC138ADT implements combinational logic decoding where binary inputs A, B, C determine which of eight outputs is driven LOW while all others remain HIGH. All outputs are active-low, and decoding only occurs when G1 is HIGH and both G2A and G2B are LOW - enabling hierarchical expansion without external inverters.

Its CMOS design supports mixed-voltage interfacing: inputs tolerate 5.5 V regardless of VCC (1.65–3.6 V), allowing direct connection to legacy 5-V logic. Output drive strength is ±24 mA at 3.0 V, with typical VOL = 0.4 V and VOH = 2.4 V under load, ensuring robust noise margins in noisy industrial environments.

Key Specifications

Pinout & Package

SN74LVC138ADT uses the SOIC-16 (D) package: 9.90 mm × 3.91 mm body, 1.27 mm pitch, surface-mount, plastic body with gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC138N and 74LVT138PW, the SN74LVC138ADT uniquely balances wide voltage operation (1.65–3.6 V), 5.5-V input tolerance, and 5.8-ns speed - making it the optimal choice for modern mixed-voltage industrial designs requiring flexibility and reliability.

Availability

SN74LVC138ADT is available at Aetrix Electronics and suitable for industrial control, LED display subsystems, and factory automation equipment requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for SN74LVC138ADT 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The SN74LVC138ADT belongs to TI's LVC logic family, designed specifically for low-voltage, high-speed, mixed-signal system interfacing - emphasizing voltage flexibility, noise resilience, and seamless integration with microcontrollers and FPGAs.

FAQ

What is the maximum propagation delay of the SN74LVC138ADT at 3.3 V?

The maximum propagation delay of the SN74LVC138ADT is 5.8 ns at VCC = 3.3 V ± 0.3 V, measured from any enable or select input to any output (Y0–Y7). This value is specified under standard load conditions (CL = 50 pF) and represents worst-case timing for timing-critical address decoding or demultiplexing in the SN74LVC138ADT.

Can the SN74LVC138ADT accept 5-V input signals while powered at 1.8 V?

Yes, the SN74LVC138ADT accepts input voltages up to 5.5 V regardless of VCC, including when powered at 1.8 V. This 5.5-V tolerance is inherent to its input structure and allows safe interfacing with 5-V microcontrollers or sensors without external level shifters - a confirmed feature of the SN74LVC138ADT.

What package type does the SN74LVC138ADT use, and what are its dimensions?

The SN74LVC138ADT uses the SOIC-16 (D) package: 9.90 mm × 3.91 mm body size, 1.27 mm lead pitch, and gull-wing surface-mount leads. Its mechanical drawing is documented in TI's SLMA005 package outline, and the SN74LVC138ADT is fully compatible with standard SOIC-16 reflow profiles and pick-and-place tooling.

How many enable inputs does the SN74LVC138ADT have, and what are their logic polarities?

The SN74LVC138ADT has three enable inputs: G1 (active-HIGH), G2A (active-LOW), and G2B (active-LOW). All three must be simultaneously asserted - i.e., G1 = HIGH and G2A = G2B = LOW - for any output (Y0–Y7) to respond to select inputs A, B, C. This configuration enables flexible hierarchical decoding in the SN74LVC138ADT.

Is the SN74LVC138ADT suitable for LED matrix applications, and why?

Yes, the SN74LVC138ADT is widely used in LED matrix column driving due to its eight active-low outputs, ±24 mA drive capability at 3.0 V, and precise timing (5.8 ns max delay). Its outputs sink current directly for common-anode displays, and the enable logic prevents multiple columns from activating simultaneously - a key requirement verified in TI's application note SNVA864 for the SN74LVC138ADT.