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Texas Instruments SN54ALS251J
- Part No.:
- SN54ALS251J
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-CDIP (0.300", 7.62mm)
- Datasheet:
-
SN54ALS251J.pdf
- Description:
- 1-OF-8 DATA SELECTORS/MULTIPLEXE
- Quantity:
- Payment:
- Shipping:
Inventory:2,329
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Product details
Overview
SN54ALS251J from Texas Instruments is a high-speed 8-line to 1-line data selector/multiplexer with three-state outputs, designed for military-grade logic systems operating from –55°C to +125°C. It features TTL-compatible inputs, 16-pin CDIP package, propagation delay of 11 ns (max) at VCC = 5 V, and supports dual-function selection via A/B/C address lines and enable control (G̅). It is used in real-time signal routing within avionics data acquisition subsystems.
For engineers reviewing the SN54ALS251J datasheet, SN54ALS251J pinout, SN54ALS251J application, or SN54ALS251J equivalent, key selection considerations include its military temperature range, three-state output capability for bus sharing, TTL-level compatibility, and guaranteed AC/DC performance under extreme environmental stress.
Technical Context
The SN54ALS251J implements a functionally complete 8:1 multiplexer with active-low enable (G̅) and complementary outputs (Y and Y̅), enabling simultaneous true and inverted data routing. Its ALS (Advanced Low-Power Schottky) logic family delivers lower power consumption than standard LS while maintaining compatible voltage thresholds and drive strength.
Input address decoding uses three binary-select lines (A, B, C) to route one of eight data inputs (D0–D7) to the output stage, which is gated by G̅. The three-state outputs allow direct connection to shared data buses without external isolation, with output disable occurring when G̅ = HIGH.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS (Advanced Low-Power Schottky) - enables 11 ns propagation delay with 19 mW typical power per gate at 5 V. |
| Operating Temperature | –55°C to +125°C - qualified for extended-range military applications including airborne and space-qualified systems. |
| Propagation Delay (tPD) | 11 ns max (VCC = 5 V, TA = 25°C) - ensures deterministic timing in synchronous digital control loops. |
| Output Type | Three-state (active-low enable) - allows bidirectional bus arbitration without external tri-state buffers. |
| Supply Voltage (VCC) | 4.5 V to 5.5 V - maintains stable operation across wide input rail tolerances common in ruggedized power supplies. |
| Input Compatibility | TTL-level - interfaces directly with legacy 74LS, 74S, and 74F series without level-shifting circuitry. |
Pinout & Package
SN54ALS251J is housed in a hermetically sealed 16-pin Ceramic Dual In-line Package (CDIP, suffix J), rated for military reliability and long-term storage stability. Package dimensions conform to JEDEC MS-012, with 0.3-inch body width and 0.1-inch lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G̅) | Active-low Output Enable | Drives outputs into high-impedance state when HIGH; required for bus-sharing configurations. |
| 2–9 (D0–D7) | Data Inputs | Eight parallel digital inputs; only one routed to output based on A/B/C address code. |
| 10 (Y̅) | Inverted Output | Complementary three-state output - provides inverted logic level of selected input. |
| 11 (Y) | True Output | Non-inverted three-state output - primary data path for selected input. |
| 12–14 (C, B, A) | Address Select Lines | Binary-coded inputs selecting D0–D7; A = LSB, C = MSB (e.g., CBA = 011 selects D3). |
| 15 (VCC) | Positive Supply | +5 V supply pin; decoupling capacitor placement near this pin is critical for noise immunity. |
| 16 (GND) | Ground Reference | Signal and power return; must be low-inductance connection to minimize ground bounce. |
Key Features
| Feature | Design Value |
|---|---|
| Three-state outputs with common enable | Enables direct connection to shared data buses in multi-master architectures without contention risk. |
| ALS logic speed-power optimization | Delivers 11 ns tPD with 19 mW typical power - 30% faster and 25% lower power than equivalent 74LS251. |
| Military temperature qualification | Tested and screened per MIL-PRF-38535 Class B requirements - suitable for flight-critical avionics and ground-based radar systems. |
| Complementary true/inverted outputs | Eliminates need for external inverters in differential signaling or parity generation circuits. |
| TTL-compatible input thresholds | Accepts standard 0.8 V / 2.0 V VIH/VIL levels - interoperable with legacy 74-series logic families without interface logic. |
Applications
| Avionics Data Multiplexing | Radar Signal Routing |
|---|---|
|
Use Scenario: Consolidating analog-to-digital converter outputs from multiple sensor channels onto a single serial bus in a fly-by-wire control computer. IC Role / Device Role / Timing Role: 8:1 multiplexer selecting discrete ADC samples under microcontroller address control; synchronized to system clock edge. Use Value: Reduces PCB trace count and interconnect complexity while preserving sample integrity through deterministic propagation delay. |
Use Scenario: Dynamically switching between RF receiver front-end gain stages during pulse-Doppler radar mode transitions. IC Role / Device Role / Timing Role: High-reliability signal path selector enabling rapid reconfiguration of analog signal chains without mechanical relays. Use Value: Enables sub-microsecond channel switching with no contact wear or settling delay - critical for real-time adaptive waveform processing. |
| Secure Crypto Module I/O Control | Missile Guidance Telemetry Interface |
|
Use Scenario: Isolating cryptographic key registers from external debug ports using hardware-enforced access gating. IC Role / Device Role / Timing Role: Three-state-enabled data gate preventing unauthorized readout during secure boot or key loading sequences. Use Value: Provides physical-layer security enforcement independent of firmware state - immune to software exploits or debugger intrusion. |
Use Scenario: Routing telemetry data streams from inertial measurement units (IMUs), GPS receivers, and seeker sensors to a common downlink transmitter. IC Role / Device Role / Timing Role: Time-sliced multiplexer ensuring deterministic latency for guidance loop feedback signals. Use Value: Guarantees worst-case 11 ns path delay across all selected channels - essential for closed-loop stability in high-G maneuvering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN54LS251J | Standard LS logic family; 22 ns max tPD, higher power (35 mW), same pinout and function. | Qualified for same military temperature range but lacks ALS speed/power optimization. | Select when legacy LS timing margins are acceptable and cost sensitivity outweighs performance gains. |
| JM38510/30905BEA | QML-38535 Class V qualified; identical ALS electrical specs and pinout, but with enhanced screening and lot traceability. | Required for DoD-accredited spaceflight or nuclear-hardened platforms where radiation tolerance and full pedigree documentation are mandatory. | Choose for programs requiring QML-V certification, extended reliability testing, or full lot traceability per MIL-STD-883. |
Compared with SN54LS251J, SN54ALS251J reduces propagation delay by 50% and power by 46% without layout changes; JM38510/30905BEA adds QML-V compliance but requires formal qualification documentation review.
Availability
SN54ALS251J is available at Aetrix Electronics and suitable for avionics data acquisition, radar signal routing, and secure crypto module I/O control requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN54ALS251J 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 aerospace, defense, and industrial markets.
The SN54ALS251J belongs to TI's military-grade ALS logic family, engineered specifically for high-speed, low-power digital signal routing in mission-critical systems where thermal resilience and timing predictability are non-negotiable.
FAQ
What is the maximum propagation delay specification for SN54ALS251J?
The maximum propagation delay (tPD) for SN54ALS251J is 11 ns under standard test conditions (VCC = 5 V, TA = 25°C, CL = 15 pF). This value is guaranteed across the full military temperature range (–55°C to +125°C) per the SDLS085 datasheet revision March 1988. SN54ALS251J achieves this performance through Advanced Low-Power Schottky transistor design, making it significantly faster than the standard LS variant.
Does SN54ALS251J support three-state output operation?
Yes, SN54ALS251J features fully specified three-state outputs controlled by the active-low enable input (G̅, Pin 1). When G̅ is HIGH, both Y and Y̅ outputs enter high-impedance states, allowing SN54ALS251J to share a common data bus with other three-state devices. This functionality is electrically characterized and guaranteed over the full military temperature range, with defined off-state leakage and transition times documented in the SN54ALS251J datasheet.
What package type is used for SN54ALS251J?
SN54ALS251J is packaged in a 16-pin Ceramic Dual In-line Package (CDIP) with hermetic sealing and tin-lead (SNPB) lead finish, designated by the "J" suffix. This package meets MIL-STD-1835 requirements and is rated for operation from –55°C to +125°C. Its dimensions follow JEDEC outline MS-012, with 0.3-inch body width and 0.1-inch lead pitch - identical to other military-grade 16-pin CDIP logic devices.
How does SN54ALS251J differ from SN54LS251J?
SN54ALS251J uses Advanced Low-Power Schottky (ALS) technology, delivering 11 ns max propagation delay and ~19 mW typical power dissipation, whereas SN54LS251J uses standard Low-Power Schottky (LS) with 22 ns max tPD and ~35 mW power. Both share identical pinout, function, and military temperature rating, but SN54ALS251J provides superior speed-power trade-off. SN54ALS251J is not a drop-in replacement for SN54LS251J unless timing margins are verified.
Is SN54ALS251J RoHS compliant?
No, SN54ALS251J is not RoHS compliant. It uses a tin-lead (SNPB) solder finish and is manufactured under legacy military specifications that predate RoHS requirements. The part marking "SN54ALS251J" and packaging data confirm SNPB lead finish and exemption from RoHS compliance per TI's packaging addendum. For RoHS-compliant alternatives, consider commercial-grade variants like SN74LS251DR, though these lack military temperature rating and screening.
SN54ALS251J Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 54ALS
- Package/Case:
- 16-CDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Data Selector/Multiplexer
- Circuit:
- 1 x 8:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 1mA, 12mA
- 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
SN54ALS251J FAQ
1.How can I place an order for SN54ALS251J through Aetrix?
Please submit a Request for Quotation (RFQ) for SN54ALS251J 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 SN54ALS251J reliable?
The price and inventory of SN54ALS251J are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN54ALS251J is usually 5 days.
3.What payment methods are accepted for SN54ALS251J?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN54ALS251J transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN54ALS251J?
SN54ALS251J orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN54ALS251J 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 SN54ALS251J?
For technical support, including SN54ALS251J datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN54ALS251J requirements.
6.How does Aetrix verify that SN54ALS251J is sourced from the original manufacturer or authorized distributors?
All SN54ALS251J 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 SN54ALS251J meets industry standards.
7.What is the process for return or replacement of SN54ALS251J?
All SN54ALS251J units undergo pre-shipment inspection (PSI). If there is an issue with SN54ALS251J, 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 SN54ALS251J part is unused and in its original packaging.
Return procedure for SN54ALS251J:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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