Diodes Incorporated 74HCT138S16-13

Overview

74HCT138S16-13 from Diodes Incorporated is a high-speed CMOS 3-to-8 line decoder/demultiplexer designed for memory chip-select decoding, demultiplexing, peripheral control, logic expansion, and digital address decoding applications. The device accepts a three-bit binary weighted address on A0, A1, and A2 and, when enabled, drives one selected output LOW while the remaining seven outputs stay HIGH.

As part of the Diodes Incorporated 74HCT logic portfolio, 74HCT138S16-13 combines 4.5V to 5.5V operation, TTL-compatible HCT input behavior, active-low decoded outputs, three enable inputs, CMOS low power consumption, Schmitt-trigger action at all inputs, and SO-16 tape-and-reel packaging. For engineers reviewing the 74HCT138S16-13 datasheet, 74HCT138S16-13 pinout, 74HCT138S16-13 application, or 74HCT138S16-13 equivalent, this device is widely used in memory address decoding, MCU peripheral selection, demultiplexer circuits, single-line peripheral control, embedded logic boards, industrial electronics, and 5V TTL-compatible control systems.

Technical Context

In digital logic systems, 74HCT138S16-13 operates as a 1-of-8 decoder by converting the three address inputs A0, A1, and A2 into one selected active-low output among Y0 to Y7. The device is enabled only when E1 and E2 are LOW and E3 is HIGH; otherwise, all outputs remain HIGH. This enable structure makes the device useful for address-qualified chip-select generation and output gating.

The HCT logic family is designed for TTL-level input compatibility while retaining CMOS low-power behavior. This makes 74HCT138S16-13 suitable for 5V systems where the driving logic may not provide full CMOS-level input HIGH voltage, such as legacy TTL, LS-TTL, microcontroller, bus-interface, or mixed logic environments.

The multiple enable inputs allow decoder expansion without complex external logic. Diodes Incorporated notes that the device can be expanded to create 4-to-16 line decoder versions without additional parts and 5-to-32 line decoder versions with one inverter. It can also be used for demultiplexing or simple serial bit-stream based peripheral control in microcontroller systems.

Key Specifications

Pinout & Package

The 74HCT138S16-13 pinout follows the standard 16-pin 3-to-8 decoder layout. Pins 1 to 3 are address inputs A0, A1, and A2; pins 4 to 6 are enable inputs E1, E2, and E3; pins 7 and 9 to 15 are active-low outputs; pin 8 is ground; and pin 16 is VCC.

For PCB implementation, the VCC pin should be decoupled close to the SO-16 package, unused inputs should be tied to VCC or ground, and the active-low output polarity should be verified against downstream memory, latch, buffer, or peripheral-select circuits. The SO-16 package provides a wider footprint than TSSOP versions, which may be useful for existing legacy layouts or easier assembly inspection.

Key Features

• 3-to-8 line decoder/demultiplexer with active-low outputs.
• TTL-compatible HCT inputs for 5V logic systems.
• Two active-low enables and one active-high enable support gating and cascading.
• One selected output goes LOW while all other outputs remain HIGH when enabled.
• Wide 4.5V to 5.5V supply range for standard 5V logic rails.
• Sinks or sources 8mA at VCC = 4.5V.
• Schmitt-trigger action at all inputs improves input transition robustness.
• Inputs accept up to 6.0V for common 5V logic-interface use.
• Supports decoder expansion to 4-to-16 or 5-to-32 line structures.
• Lead-free, RoHS-compliant, halogen-free, antimony-free Green device.
• SO-16 tape-and-reel packaging supports production assembly.

Applications

Equivalent & Alternatives

When evaluating 74HCT138S16-13 equivalent devices, engineers should compare logic family, TTL versus CMOS input thresholds, supply-voltage range, package footprint, output polarity, propagation delay, output drive, ESD rating, environmental compliance, and manufacturer qualification.

Compared with 74HCT138T16-13, 74HCT138S16-13 is optimized for SO-16 package layouts while maintaining the same Diodes Incorporated 74HCT138 decoder/demultiplexer function. 74HCT138S16-13 vs 74HC138S16-13 selection depends on whether the system requires TTL-compatible HCT input thresholds or CMOS-level HC input thresholds.

Quality

74HCT138S16-13 should be sourced as original Diodes Incorporated components through traceable and controlled supply channels. Quality verification procedures may include package inspection, top-mark validation, solderability testing, pin continuity checks, supply-current review, input-threshold verification, truth-table testing, output-level measurement, and incoming inspection according to standard logic production requirements.

Because the device is frequently used for chip-select and peripheral-control signals, system reliability depends on correct enable polarity, stable VCC decoupling, valid TTL-compatible input levels, clean address timing, correct active-low output interpretation, and proper handling of unused inputs. Traceable sourcing supports manufacturing quality and reduces counterfeit supply-chain risk for standard logic production programs.

Availability

74HCT138S16-13 available at Aetrix Electronics and suitable for memory chip-select decoding, demultiplexing, single-line peripheral control, microcontroller expansion, embedded digital logic, industrial control boards, and 5V TTL-compatible logic systems requiring stable component supply and repeatable production support.

Supply support may include scheduled delivery planning, volume procurement support, BOM continuity assistance, traceable sourcing management, and long-term availability support for OEM manufacturers, embedded-system developers, industrial-control designers, logic-board builders, and electronics production programs.

For production deployment, confirming HCT input compatibility, 5V supply requirements, SO-16 package footprint, active-low output polarity, propagation-delay margin, reel packaging, and sourcing continuity helps reduce procurement risk and improve manufacturing stability.

Manufacturer

Diodes Incorporated is a semiconductor manufacturer providing discrete, logic, analog, power-management, timing, connectivity, protection, and switching products for consumer, industrial, computing, communication, automotive, and embedded electronics applications.

The Diodes Incorporated logic portfolio focuses on standard CMOS and HCT logic functions, package availability, low-power operation, TTL-compatible and CMOS-compatible logic families, environmental compliance, and stable supply support for embedded digital systems, control logic, address decoding, and board-level interface applications.

FAQ

What is 74HCT138S16-13 used for?

74HCT138S16-13 is used for 3-to-8 address decoding, memory chip-select generation, demultiplexing, microcontroller peripheral control, logic expansion, and TTL-compatible 5V digital control circuits.

Where can I find the 74HCT138S16-13 datasheet download?

The 74HCT138S16-13 datasheet is available from Diodes Incorporated and includes description, pin assignments, function table, logic diagram, electrical characteristics, switching specifications, ordering information, marking data, and package dimensions.

What should be considered in 74HCT138S16-13 PCB design?

PCB implementation should provide close VCC decoupling, stable grounding, valid TTL-compatible input levels, clean address and enable routing, tied unused inputs, and verification that active-low outputs match the downstream logic polarity.

Are the outputs of 74HCT138S16-13 active LOW?

Yes. 74HCT138S16-13 has eight active-low outputs. When the decoder is enabled, one selected output is LOW and the remaining outputs are HIGH.

What are common 74HCT138S16-13 equivalent solutions?

Common alternatives include 74HCT138T16-13, 74HC138S16-13, CD74HCT138M, and SN74HCT138DR depending on package footprint, input-threshold requirements, supply voltage, timing, approved manufacturer list, and sourcing continuity.