Texas Instruments SN74LVC138ARGYRG4

Overview

SN74LVC138ARGYRG4 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 5.8 ns max propagation delay at 3.3 V and inputs tolerant to 5.5 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), used for memory decoding and LED matrix column selection.

For engineers reviewing the SN74LVC138ARGYRG4 datasheet, SN74LVC138ARGYRG4 pinout, SN74LVC138ARGYRG4 application, or SN74LVC138ARGYRG4 equivalent, key selection criteria include supply voltage range (1.65–3.6 V), input overvoltage tolerance (5.5 V), propagation delay (≤5.8 ns @ 3.3 V), output drive capability (±24 mA), and QFN-16 thermal performance (R_θJA = 108.9 °C/W).

Technical Context

The SN74LVC138ARGYRG4 implements a standard 3-to-8 binary decoder with active-low outputs and three enable inputs: G1 (active high), G2A and G2B (both active low). All three enables must be asserted for any output to activate; deasserting any enable forces all Y0–Y7 outputs high.

Its CMOS design supports mixed-voltage interfacing: inputs accept up to 5.5 V regardless of V_CC, enabling direct connection to 5-V logic while powered from 1.8-V or 3.3-V rails. Output switching is rail-to-rail (0 V to V_CC), with balanced rise/fall times and specified ground bounce (V_OLP < 0.8 V) and undershoot (V_OHV > 2 V) at 3.3 V.

Key Specifications

Pinout & Package

SN74LVC138ARGYRG4 uses a 16-pin QFN package (RGY) with 3.6 mm × 4.4 mm body size, exposed thermal pad, and no lead finish restrictions (RoHS-compliant NiPdAu).

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, SN74LVC138ARGYRG4 offers superior high-speed performance in a thermally enhanced QFN package ideal for space-constrained industrial and portable designs, while maintaining full 1.65–3.6-V compatibility and 5.5-V input tolerance.

Availability

SN74LVC138ARGYRG4 is available at Aetrix Electronics and suitable for LED matrix displays, memory address decoding, and industrial I/O expansion requiring stable component supply, RoHS compliance, and consistent QFN-16 sourcing.

Supply support for SN74LVC138ARGYRG4 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 logic families and industrial-grade packaging.

The SN74LVC138A product line was designed for high-performance memory decoding and data routing in space- and power-constrained systems, emphasizing low propagation delay, wide supply range, and robust mixed-voltage interoperability.

FAQ

What is the maximum operating frequency supported by SN74LVC138ARGYRG4?

SN74LVC138ARGYRG4 does not specify a maximum clock frequency because it is a combinational logic device without internal clocking. Its usable switching rate is determined by propagation delay (≤5.8 ns @ 3.3 V) and load capacitance. For typical 30-pF loads, reliable operation exceeds 100 MHz in demultiplexing mode, though system-level timing margins must account for setup/hold and interconnect delays.

Can SN74LVC138ARGYRG4 interface directly with a 5-V microcontroller?

Yes, SN74LVC138ARGYRG4 accepts input voltages up to 5.5 V regardless of V_CC, allowing direct connection to 5-V GPIOs. When powered from 3.3 V, its outputs swing 0–3.3 V - sufficient to drive 3.3-V logic inputs. For bidirectional 5-V compatibility, external level-shifting circuitry is required on outputs.

Is the thermal pad on the SN74LVC138ARGYRG4 package required to be soldered?

Yes, the exposed thermal pad on SN74LVC138ARGYRG4 must be soldered to the PCB ground plane to achieve the published R_θJA of 108.9 °C/W. Omitting thermal pad connection increases junction temperature significantly, potentially exceeding absolute maximum ratings under sustained 24-mA output loading.

How does the enable logic work on SN74LVC138ARGYRG4?

SN74LVC138ARGYRG4 requires G1 = HIGH, G2A = LOW, and G2B = LOW simultaneously to enable decoding. If any enable is violated, all Y0–Y7 outputs go HIGH (inactive state). This three-input enable scheme allows flexible cascading: G1 can serve as data input for demultiplexing, while G2A/G2B control hierarchical chip selection.

What is the recommended bypass capacitor for SN74LVC138ARGYRG4?

A 0.1-µF X7R ceramic capacitor is recommended directly between V_CC and GND pins of SN74LVC138ARGYRG4, placed within 2 mm of the package. For systems with high-frequency noise, paralleling with a 1-µF capacitor improves broadband suppression. The thermal pad must also connect to the ground plane to complete the low-inductance return path.