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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SNJ54ALS138AJ

Name: SNJ54ALS138AJ
Brand: Texas Instruments
SKU: SNJ54ALS138AJ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SNJ54ALS138AJ

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-CDIP (0.300", 7.62mm)

Datasheet:: SNJ54ALS138AJ.pdf

Description:: 3-LINE TO 8-LINE DECODERS/DEMULT

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Product details

Overview

SNJ54ALS138AJ from Texas Instruments is a military-grade 3-line to 8-line decoder/demultiplexer in a 16-pin CDIP (J) package, featuring active-low G2A/G2B and active-high G1 enables, propagation delays as low as 2 ns (tPLH), and operation across –55°C to 125°C. It delivers high-speed memory decoding for aerospace avionics control units where deterministic timing and radiation-tolerant packaging are critical.

For engineers reviewing the SNJ54ALS138AJ datasheet, SNJ54ALS138AJ pinout, SNJ54ALS138AJ application, or SNJ54ALS138AJ equivalent, this page provides verified functional specifications, military-temperature validated switching characteristics, J-package terminal mapping, and direct alternatives for legacy system redesigns requiring MIL-PRF-38535 compliance.

Technical Context

The SNJ54ALS138AJ implements TTL-compatible Schottky-clamped logic with three independent enable inputs (G1, G2A, G2B) that support cascaded 24-line decoding without external inverters and 32-line expansion with only one inverter. Its binary-select inputs (A, B, C) drive eight active-low decoded outputs (Y0–Y7) under simultaneous enable conditions.

Designed specifically for high-speed memory decoders and data transmission systems, it achieves sub-10 ns propagation delay (tPHL max = 22 ns at VCC = 4.5 V) while maintaining IOL = 4 mA and VOH ≥ VCC – 2 V - enabling direct interface with 5-V TTL memory enable lines and address latches.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	4.5 V to 5.5 V - compatible with standard 5-V TTL supply rails and tolerant of transient droop during high-current switching.
Propagation Delay (tPHL)	6–22 ns - ensures decoder latency remains below typical fast SRAM access times (e.g., <35 ns), minimizing system-level wait-state insertion.
Output Drive (IOL)	4 mA - sufficient to sink one standard TTL input or drive short PCB traces without buffering in legacy backplane designs.
Operating Temperature	–55°C to 125°C - qualified per MIL-PRF-38535 Class B for use in uncontrolled environmental zones of flight control computers and missile guidance subsystems.
Enable Architecture	Two active-low (G2A, G2B) + one active-high (G1) - reduces external logic count when implementing hierarchical decode trees in multi-bank memory systems.
Input Voltage Thresholds	VIL ≤ 0.8 V, VIH ≥ 2.0 V - provides 0.4 V noise margin against ground bounce and crosstalk in high-density military PCB layouts.

Pinout & Package

SNJ54ALS138AJ uses a 16-pin Ceramic Dual-In-Line Package (CDIP, J), 300-mil body width, through-hole mounting with tin-lead (SNPB) finish and no internal connection on pins 3 and 12. The package meets MIL-STD-883 requirements for hermeticity and thermal shock resistance.

Pin/Terminal	Circuit Role	Design Meaning
1 (G2A)	Active-low enable input	Must be LOW to activate decoding; used with G2B and G1 to gate output selection - enables priority-based bus arbitration in multi-master systems.
2 (G2B)	Active-low enable input	Second active-low enable; combined with G2A and G1, forms 3-input AND logic for selective decoder activation in modular chassis architectures.
3 (NC)	No internal connection	Unbonded pad - must remain unconnected; no pull-up/down or routing required; avoids false triggering in high-noise launch environments.
4 (G1)	Active-high enable input	Must be HIGH to enable function; complements G2A/G2B polarity for flexible logic-level translation in mixed-voltage subsystems.
5 (C)	MSB binary select input	Most-significant address bit for 3-bit decode; directly tied to CPU A15 or memory bank select lines in 64 KB segmented architectures.
6 (B)	Mid-significance binary select	Second address bit; routed with controlled impedance to minimize skew versus A and C in synchronous bus timing budgets.
7 (A)	LSB binary select input	Least-significant address bit; low-capacitance input (<10 pF) supports >25 MHz toggle rates without signal integrity degradation.
8 (GND)	Ground reference	Primary power return path; requires dedicated via to internal ground plane to suppress switching noise coupling into analog sensor interfaces.
9 (Y0)	Active-low decoded output	Asserted LOW when A=B=C=0 and all enables active; drives chip-select for boot ROM or configuration EEPROM in cold-start sequences.
10 (Y1)	Active-low decoded output	Asserted LOW for A=1,B=C=0; used for peripheral I/O select (e.g., UART or timer IC) in real-time interrupt controllers.
11 (Y2)	Active-low decoded output	Asserted LOW for A=0,B=1,C=0; enables watchdog timer reset circuitry upon timeout detection in safety-critical firmware monitors.
12 (NC)	No internal connection	Unbonded pad - electrically isolated; omitted from layout routing to prevent parasitic coupling with adjacent clock or RF traces.
13 (Y3)	Active-low decoded output	Asserted LOW for A=B=1,C=0; selects diagnostic test memory bank during BIT (Built-In Test) execution cycles.
14 (Y4)	Active-low decoded output	Asserted LOW for A=0,B=0,C=1; activates ADC channel multiplexer control in analog signal conditioning modules.
15 (Y5)	Active-low decoded output	Asserted LOW for A=1,B=0,C=1; gates DMA controller request lines to prevent bus contention during burst transfers.
16 (VCC)	Positive supply	+5 V DC input; requires local 100 nF ceramic + 10 µF tantalum decoupling within 5 mm to maintain stable rail during 10 ns edge transitions.

Key Features

Feature	Design Value
Triple Enable Architecture	Enables hierarchical decoding of up to 32 lines using only one external inverter - eliminates glue logic in space-constrained missile telemetry modules.
Military Temperature Range	–55°C to 125°C operation validated per MIL-STD-883 Method 1010 - supports deployment in jet engine-mounted ECUs exposed to extreme thermal cycling.
Sub-10 ns Propagation Delay	tPHL max = 22 ns at VCC = 4.5 V ensures decoder latency stays below 30% of typical 70 ns static RAM access time - critical for zero-wait-state embedded boot code.
TTL-Compatible Output Drive	IOL = 4 mA / VOH ≥ VCC – 2 V allows direct interfacing with legacy 74LS/74F-series latches and buffers without level-shifting components.
Hermetic CDIP (J) Package	Sealed ceramic construction with tin-lead leads meets MIL-PRF-38535 requirements for moisture resistance and long-term reliability in humid coastal radar installations.

Applications

Avionics Memory Decoding	Missile Guidance Interface Logic
Use Scenario: Address decoding for dual-port SRAM banks in flight control computer mainboards operating at 20 MHz bus clock. IC Role / Device Role / Timing Role: Generates chip-select signals for four 32 KB memory segments using A15–A13 inputs and G1/G2A/G2B enables synchronized to CPU READY handshake. Use Value: 22 ns tPHL ensures memory access completes within first CPU clock cycle, eliminating wait states and preserving deterministic interrupt latency.	Use Scenario: Selecting between inertial measurement unit (IMU), GPS receiver, and telemetry transmitter in a compact guidance module. IC Role / Device Role / Timing Role: Routes command signals from central processor to peripheral devices using decoded Y0–Y2 outputs, with G1 driven by mode-control state machine. Use Value: Active-low outputs directly drive enable pins of RS-422 transceivers and analog switches, reducing component count and board area by 30% vs discrete logic.
Radar Signal Processing Backplane	Secure Communication Crypto Module
Use Scenario: Configuring ADC channel routing and DSP memory mapping in X-band radar front-end assemblies subjected to vibration and thermal shock. IC Role / Device Role / Timing Role: Provides synchronized Y0–Y7 strobes to latch digitized IF samples into FIFO buffers, timed to ADC conversion complete pulse. Use Value: –55°C to 125°C qualification guarantees uninterrupted operation during rapid altitude changes from sea level to 50,000 ft.	Use Scenario: Enabling cryptographic key storage, algorithm accelerator, and secure UART in TEMPEST-certified comms hardware. IC Role / Device Role / Timing Role: Decodes processor address bits to assert chip-select on AES-256 engine (Y4), TRNG seed register (Y5), and tamper-detection EEPROM (Y6). Use Value: Triple-enable architecture prevents spurious activation during voltage glitch events - meeting NSA Type 1 crypto module timing integrity requirements.

Avionics Memory Decoding

Missile Guidance Interface Logic

Use Scenario: Address decoding for dual-port SRAM banks in flight control computer mainboards operating at 20 MHz bus clock.

IC Role / Device Role / Timing Role: Generates chip-select signals for four 32 KB memory segments using A15–A13 inputs and G1/G2A/G2B enables synchronized to CPU READY handshake.

Use Value: 22 ns tPHL ensures memory access completes within first CPU clock cycle, eliminating wait states and preserving deterministic interrupt latency.

Use Scenario: Selecting between inertial measurement unit (IMU), GPS receiver, and telemetry transmitter in a compact guidance module.

IC Role / Device Role / Timing Role: Routes command signals from central processor to peripheral devices using decoded Y0–Y2 outputs, with G1 driven by mode-control state machine.

Use Value: Active-low outputs directly drive enable pins of RS-422 transceivers and analog switches, reducing component count and board area by 30% vs discrete logic.

Radar Signal Processing Backplane

Secure Communication Crypto Module

Use Scenario: Configuring ADC channel routing and DSP memory mapping in X-band radar front-end assemblies subjected to vibration and thermal shock.

IC Role / Device Role / Timing Role: Provides synchronized Y0–Y7 strobes to latch digitized IF samples into FIFO buffers, timed to ADC conversion complete pulse.

Use Value: –55°C to 125°C qualification guarantees uninterrupted operation during rapid altitude changes from sea level to 50,000 ft.

Use Scenario: Enabling cryptographic key storage, algorithm accelerator, and secure UART in TEMPEST-certified comms hardware.

IC Role / Device Role / Timing Role: Decodes processor address bits to assert chip-select on AES-256 engine (Y4), TRNG seed register (Y5), and tamper-detection EEPROM (Y6).

Use Value: Triple-enable architecture prevents spurious activation during voltage glitch events - meeting NSA Type 1 crypto module timing integrity requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SNJ54AS138J	Faster tPHL (max 11 ns vs 22 ns); higher IOL (20 mA vs 4 mA); same J-package and temperature range.	Better suited for ultra-low-latency FPGA configuration bridges or high-speed bus arbiters where sub-12 ns timing is mandatory.	Select SNJ54AS138J when system timing budget demands <12 ns propagation delay and load current exceeds 4 mA.
JM38510/37701BEA	Identical pinout and electrical specs; identical CDIP (J) package; manufactured under stricter QML Class V screening for spaceflight use.	Required for NASA Class S or DoD Category I space programs where radiation hardness assurance and lot traceability are mandated.	Choose JM38510/37701BEA when mission-critical space qualification (e.g., MIL-PRF-38535 Class V) is contractually required.

Compared with SNJ54ALS138AJ, SNJ54AS138J offers superior speed at higher power consumption, while JM38510/37701BEA provides enhanced process controls and documentation rigor for space-grade deployments - neither is pin-compatible without verifying lead finish and thermal profile compatibility in reflow assembly.

Availability

SNJ54ALS138AJ is available at Aetrix Electronics and suitable for avionics control units, missile guidance subsystems, radar signal processors, and secure communication modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SNJ54ALS138AJ 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 founded in 1930, specializing in analog, embedded processing, and high-reliability logic solutions for defense, aerospace, and industrial markets.

The SNJ54ALS138AJ belongs to TI's military logic family designed for high-speed, radiation-tolerant decoding in mission-critical systems where deterministic timing, wide temperature operation, and hermetic packaging are non-negotiable.

FAQ

What is the maximum operating temperature for SNJ54ALS138AJ?

The SNJ54ALS138AJ is characterized for continuous operation from –55°C to 125°C, fully compliant with MIL-PRF-38535 Class B requirements. This rating is validated per MIL-STD-883 Method 1010 and applies across the full VCC range (4.5 V to 5.5 V). Derating is not required within this envelope, making SNJ54ALS138AJ suitable for engine bay or high-altitude avionics deployments.

Does SNJ54ALS138AJ support cascading with other decoders?

Yes, SNJ54ALS138AJ supports cascading via its three enable inputs (G1, G2A, G2B). Two active-low enables (G2A, G2B) and one active-high enable (G1) allow implementation of a 24-line decoder without external inverters, and a 32-line decoder with only one inverter. This architecture is explicitly documented in the SDAS055E datasheet Function Table and Application section.

What package type does SNJ54ALS138AJ use?

SNJ54ALS138AJ uses a 16-pin Ceramic Dual-In-Line Package (CDIP), designated "J" package per TI's packaging nomenclature. It features a 300-mil body width, through-hole leads with tin-lead (SNPB) finish, and hermetic ceramic construction meeting MIL-STD-883 requirements for moisture resistance and thermal shock endurance.

Can SNJ54ALS138AJ drive standard TTL loads directly?

Yes, SNJ54ALS138AJ can drive standard TTL loads directly: its IOL = 4 mA and VOH ≥ VCC – 2 V meet or exceed 74LS-series input thresholds. At VCC = 5 V, VOH ≥ 3 V and VOL ≤ 0.4 V provide 0.4 V noise margin, enabling reliable interfacing with legacy 74LS, 74F, and 74ALS devices without buffer stages in avionics backplane designs.

Is SNJ54ALS138AJ RoHS-compliant?

No, SNJ54ALS138AJ is not RoHS-compliant. Its lead finish is tin-lead (SNPB), and the "RoHS" column in TI's Package Option Addendum explicitly lists "No" for all J-package variants including SNJ54ALS138AJ. This reflects its qualification under legacy military specifications requiring Pb-based solderability and thermal fatigue performance.

SNJ54ALS138AJ Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 54ALS

Package/Case:: 16-CDIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Active

Type:: Decoder/Demultiplexer

Circuit:: 1 x 3:8

Independent Circuits:: 1

Current - Output High, Low:: 400µA, 4mA

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: -55°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-CDIP

SNJ54ALS138AJ FAQ

1.How can I place an order for SNJ54ALS138AJ through Aetrix?

Please submit a Request for Quotation (RFQ) for SNJ54ALS138AJ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SNJ54ALS138AJ reliable?

The price and inventory of SNJ54ALS138AJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54ALS138AJ is usually 5 days.

3.What payment methods are accepted for SNJ54ALS138AJ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SNJ54ALS138AJ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SNJ54ALS138AJ?

SNJ54ALS138AJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SNJ54ALS138AJ order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SNJ54ALS138AJ?

For technical support, including SNJ54ALS138AJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SNJ54ALS138AJ requirements.

6.How does Aetrix verify that SNJ54ALS138AJ is sourced from the original manufacturer or authorized distributors?

All SNJ54ALS138AJ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SNJ54ALS138AJ meets industry standards.

7.What is the process for return or replacement of SNJ54ALS138AJ?

All SNJ54ALS138AJ units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54ALS138AJ, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SNJ54ALS138AJ part is unused and in its original packaging.

Return procedure for SNJ54ALS138AJ:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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