Texas Instruments SN74LVC138APWRE4

Overview

SN74LVC138APWRE4 from Texas Instruments is a 3-line to 8-line decoder/demultiplexer IC operating from 1.65 V to 3.6 V, with 5.8 ns max propagation delay at 3.3 V, inputs tolerant to 5.5 V, and active-low G2A/G2B plus active-high G1 enables. It drives LED matrix column selection in embedded displays.

For engineers reviewing the SN74LVC138APWRE4 datasheet, SN74LVC138APWRE4 pinout, SN74LVC138APWRE4 application, or SN74LVC138APWRE4 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 TSSOP-16 package compatibility with high-density PCB layouts.

Technical Context

The SN74LVC138APWRE4 implements a binary-decoded 3-to-8 output architecture where inputs A, B, C select one of eight active-low outputs (Y0–Y7), while G1 (active-high) and G2A/G2B (active-low) enable logic gates control overall device activation. All outputs are open-drain compatible with pull-up configurations.

Its CMOS design supports mixed-voltage interfacing: 5-V-tolerant inputs allow direct connection to legacy logic, while 1.65–3.6 V operation targets modern low-power microcontrollers and FPGAs. Propagation delay is specified per input-to-output path (A/B/C→Y, G1→Y, G2A/G2B→Y), with worst-case skew ≤1 ns across outputs at 3.3 V.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package: 5.00 mm × 4.40 mm body, 0.65 mm pitch, surface-mount, lead-free (NIPDAU), moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC138N and 74LVC138AD, SN74LVC138APWRE4 delivers superior speed (5.8 ns vs 21 ns), mixed-voltage interoperability (5.5-V inputs), and compact TSSOP packaging-making it optimal for modern industrial and embedded designs demanding density, timing precision, and voltage flexibility.

Availability

SN74LVC138APWRE4 is available at Aetrix Electronics and suitable for LED matrix displays, memory address decoding, and industrial I/O expansion requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for SN74LVC138APWRE4 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 connectivity technologies, with decades of experience in logic IC design and industrial-grade qualification.

The SN74LVC138APWRE4 belongs to TI's LVC logic family, engineered for low-voltage, high-speed digital interfacing in space-constrained, power-sensitive applications such as factory automation, building controls, and portable instrumentation.

FAQ

What is the maximum operating frequency supported by SN74LVC138APWRE4?

The SN74LVC138APWRE4 does not specify a clock frequency but supports address/data switching up to ~170 MHz based on its 5.8 ns propagation delay at 3.3 V. In practice, reliable operation depends on input signal edge rate (≤10 ns/V), load capacitance (≤50 pF), and proper bypassing. For continuous toggling, ensure setup/hold times are met per the function table-no internal clock limits apply since it is combinational logic.

Can SN74LVC138APWRE4 interface directly with a 5-V microcontroller?

Yes, SN74LVC138APWRE4 accepts input voltages up to 5.5 V while operating from 1.65–3.6 V, allowing direct connection to 5-V GPIOs without level shifters. Its inputs are 5-V tolerant, and logic thresholds scale with VCC (e.g., VIH ≥2.0 V at 3.3 V). However, outputs swing between 0 V and VCC, so external pull-ups to 5 V are required if driving 5-V loads.

What is the recommended bypass capacitor for SN74LVC138APWRE4?

A 0.1 µF ceramic capacitor is recommended directly between VCC (pin 16) and GND (pin 8) of SN74LVC138APWRE4, placed within 2 mm of the pins. For noisy environments, add a 1 µF tantalum or ceramic capacitor in parallel. This suppresses supply ripple and prevents ground bounce (VOLP < 0.8 V) during simultaneous output switching.

How does the enable logic work on SN74LVC138APWRE4?

SN74LVC138APWRE4 requires G1 HIGH and both G2A and G2B LOW to activate decoding. If any enable is inactive (G1 LOW, G2A HIGH, or G2B HIGH), all outputs Y0–Y7 go HIGH (inactive state). This three-input enable scheme allows flexible hierarchical control-for example, G1 can serve as a master enable while G2A/G2B chain multiple decoders for larger address spaces.

Is SN74LVC138APWRE4 suitable for LED multiplexing applications?

Yes, SN74LVC138APWRE4 is widely used for LED matrix column selection. Its active-low outputs sink current directly, supporting common-anode displays. With ±24 mA drive at 3.0 V and 5.8 ns delay, it enables high-refresh-rate scanning (>10 kHz) while maintaining precise timing alignment with row drivers. Thermal design must account for peak current per output (e.g., 24 mA × 8 = 192 mA total worst-case).