Texas Instruments SN74LVC138ARGYR

Overview

SN74LVC138ARGYR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in a 16-pin QFN (RGY) package, operating from 1.65 V to 3.6 V with inputs tolerant up to 5.5 V, 5.8 ns max propagation delay at 3.3 V, and active-low G2A/G2B plus active-high G1 enables. It drives LED matrix column selection in embedded display systems.

For engineers reviewing the SN74LVC138ARGYR datasheet, SN74LVC138ARGYR pinout, SN74LVC138ARGYR application, or SN74LVC138ARGYR equivalent, key selection criteria include supply voltage range, enable logic configuration, output drive strength (±24 mA), propagation delay vs. VCC, and QFN thermal performance for space-constrained PCB layouts.

Technical Context

The SN74LVC138ARGYR implements a binary-select decoder with three address inputs (A, B, C) and three enable inputs (G1 high-active, G2A/G2B low-active), where only one of eight outputs (Y0–Y7) is driven LOW per valid input combination; all others remain HIGH. Its CMOS design ensures rail-to-rail input compatibility and balanced output drive.

It supports demultiplexing by repurposing an enable input as data path control, enabling single-bit distribution across eight channels. The device exhibits latch-up immunity >250 mA per JESD17 and operates across –40°C to +85°C ambient temperature.

Key Specifications

Pinout & Package

SN74LVC138ARGYR uses a 16-pin QFN package (RGY) with 2.6 mm × 1.8 mm body size, exposed thermal pad, and 0.4 mm pitch. Pin 1 is marked by a dot; pin numbering follows standard counter-clockwise convention from top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC138N and 74LVC138PW, SN74LVC138ARGYR delivers superior high-speed performance at 1.8-V operation, smallest PCB footprint among alternatives, and lowest thermal resistance in its package class-making it optimal for modern embedded displays and compact industrial controllers.

Availability

SN74LVC138ARGYR is available at Aetrix Electronics and suitable for LED matrix drivers, memory address decoders, industrial I/O expanders, and programmable logic interfaces requiring stable component supply and long-term industrial lifecycle support.

Supply support for SN74LVC138ARGYR 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 decades of expertise in high-reliability industrial and automotive ICs.

The SN74LVC138A product line delivers low-voltage, high-speed decoding for memory systems and data-routing applications, designed specifically for power-efficient, noise-immune operation in space-constrained embedded platforms.

FAQ

What is the maximum clock frequency supported by SN74LVC138ARGYR for reliable decoding?

SN74LVC138ARGYR does not operate on a clock signal-it is combinational logic with propagation delay as the key timing parameter. At VCC = 3.3 V, its max tpd is 5.8 ns, supporting input address changes up to ~170 MHz (1/tpd). System-level timing must account for setup/hold margins relative to controlling MCU or FPGA clocks. SN74LVC138ARGYR remains fully functional across its entire recommended operating range without clock dependency.

Can SN74LVC138ARGYR safely interface with a 5-V microcontroller's GPIO pins?

Yes. SN74LVC138ARGYR inputs tolerate voltages up to 5.5 V regardless of VCC level, allowing direct connection to 5-V MCU outputs without level shifters or resistive dividers. Its outputs swing rail-to-rail (0 V to VCC), so interfacing with 5-V logic requires external pull-up resistors or a level translator on output lines-SN74LVC138ARGYR itself does not provide 5-V output drive.

How does the enable logic configuration of SN74LVC138ARGYR simplify cascaded decoder designs?

SN74LVC138ARGYR uses two active-low enables (G2A, G2B) and one active-high enable (G1), enabling straightforward expansion: for example, two SN74LVC138ARGYR devices can implement a 24-line decoder by connecting G1 of each to separate high-order address bits while sharing A/B/C and G2A/G2B. This eliminates external inverters needed with single-enable decoders, reducing component count and layout complexity.

Is the exposed thermal pad on the RGY package of SN74LVC138ARGYR electrically connected?

No-the exposed thermal pad on SN74LVC138ARGYR's RGY package is not internally connected to any die node and may be left floating or tied to GND for improved thermal conduction. TI's datasheet specifies it as non-functional electrically; however, soldering it to a GND plane significantly lowers junction-to-board thermal resistance (ψJB = 96.4°C/W), enhancing reliability under sustained 24 mA output loading.

What happens to SN74LVC138ARGYR outputs when all enable inputs are inactive?

When any enable input is inactive-i.e., G1 = LOW, or G2A = HIGH, or G2B = HIGH-all eight outputs (Y0–Y7) are forced HIGH regardless of A/B/C states. This high-impedance-equivalent behavior (outputs actively driven HIGH, not tri-stated) prevents bus contention and ensures predictable default state during system reset or idle periods. SN74LVC138ARGYR has no true high-impedance output mode.