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Texas Instruments SN74ALS257ADG4
- Part No.:
- SN74ALS257ADG4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74ALS257ADG4.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,896
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Product details
Overview
SN74ALS257ADG4 from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer with 3-state outputs, designed for bus-organized systems. It features 4-bit multiplexing, 5 V nominal supply operation, 12 mA low-level output drive, and operates across 0°C to 70°C. It interfaces directly with system buses in industrial control and legacy computing backplanes.
For engineers reviewing the SN74ALS257ADG4 datasheet, SN74ALS257ADG4 pinout, SN74ALS257ADG4 application, or SN74ALS257ADG4 equivalent, key selection criteria include 3-state bus interface capability, ALS logic family propagation delay (≤10 ns), output-enable timing (tPZL ≤18 ns), and compatibility with standard 16-pin SOIC-D packaging.
Technical Context
The SN74ALS257ADG4 implements four independent 2:1 multiplexers sharing a common A/B select line and active-low output-enable (OE) control. Each Y output enters high-impedance state when OE is high, enabling direct connection to shared data buses without loading.
It uses Advanced Low-Power Schottky (ALS) bipolar technology, delivering higher speed than LS logic while maintaining TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V) and 5 V supply operation. Propagation delays are specified at CL = 50 pF with R1/R2 = 500 Ω load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Low-Power Schottky (ALS), TTL-compatible input/output levels |
| Supply Voltage | 4.5 V to 5.5 V - ensures robust operation under noisy 5 V rail conditions |
| Output Drive | IOL = 12 mA - sufficient to drive multiple TTL inputs or short PCB traces |
| Propagation Delay | tPHL/tPLH ≤ 12 ns (A/B → Y) - supports >50 MHz bus switching in synchronous designs |
| Enable Timing | tPZL ≤ 18 ns, tPHZ ≤ 10 ns - enables fast bus arbitration and dynamic signal routing |
| Operating Temperature | 0°C to 70°C - qualified for commercial and industrial ambient environments |
| Package | 16-pin SOIC (D), 7.5 mm × 10.3 mm footprint - compatible with standard automated assembly |
Pinout & Package
SN74ALS257ADG4 is housed in a 16-pin small-outline integrated circuit (SOIC-D) package with 1.27 mm pitch, 7.5 mm body width, and 2.00 mm max height per TI NS0016A drawing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15 | Data inputs (1A/1B, 2A/2B, 3A/3B, 4A/4B) and outputs (1Y–4Y) | Four independent 2:1 mux channels; each pair selects one of two inputs to its output |
| 3 | A/B select | Global select line determining which input (A or B) passes to all Y outputs |
| 13 | OE (active-low output enable) | When high, forces all Y outputs into high-impedance state for bus isolation |
| 8 | GND | Power return reference for logic and output stages |
| 16 | VCC | +5 V supply for internal logic and output drivers |
Key Features
| Feature | Design Value |
|---|---|
| 3-State Outputs | Enables direct connection to shared data buses without external pull-ups or bus buffers |
| TTL-Compatible Inputs | VIL ≤ 0.8 V and VIH ≥ 2.0 V ensure reliable interfacing with legacy 5 V logic families |
| Low Propagation Delay | Typical tPLH/tPHL = 2–6 ns (A/B → Y) supports high-speed bus multiplexing |
| High Output Sink Current | 12 mA IOL allows driving up to 10 standard TTL loads per output |
| Standard Pinout Compatibility | Matches industry-standard 16-pin DIP/SOIC layout for drop-in replacement in existing layouts |
Applications
| Industrial PLC Backplane | Legacy Computer Data Bus |
|---|---|
Use Scenario: Routing sensor data streams from multiple I/O modules onto a shared controller bus in programmable logic controllers. IC Role / Device Role / Timing Role: Quad 2:1 multiplexer selecting between primary and redundant sensor inputs per channel under microcontroller control. Use Value: Enables hot-swappable I/O module support via OE-controlled bus isolation and deterministic 12 ns worst-case switching. | Use Scenario: Arbitrating access to a shared 8-bit data bus among multiple peripheral cards in vintage minicomputer architectures. IC Role / Device Role / Timing Role: Bus interface device allowing CPU or DMA controller to select between memory-mapped peripherals or expansion slots. Use Value: Provides 3-state isolation during bus contention, with sub-10 ns enable/disable timing ensuring cycle-accurate bus handoff. |
| Test Equipment Signal Routing | Embedded System Boot Selection |
Use Scenario: Dynamically configuring measurement paths in automated test equipment by selecting between calibration references and DUT signals. IC Role / Device Role / Timing Role: Signal path selector controlled by FPGA GPIO, enabling reconfigurable analog/digital signal chains. Use Value: Delivers consistent 0.4 V VOL at 12 mA load, preserving signal integrity across multiple routed paths without level-shifting. | Use Scenario: Choosing between primary firmware image (Flash) and recovery image (ROM) during power-on reset in embedded controllers. IC Role / Device Role / Timing Role: Address/data bus multiplexer gated by boot-mode strapping pins and reset assertion. Use Value: Guarantees glitch-free boot vector selection with tPHZ ≤ 10 ns, preventing invalid instruction fetch during mode transition. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS257AN | Same ALS logic, identical electrical specs, but in 16-pin PDIP (N) package | Through-hole mounting; suited for prototyping, repair, or legacy through-hole PCBs | Select when manual assembly, socketing, or board-level repair is required |
| SN74AS257D | Faster AS-family variant: tPHL/tPLH ≤ 6 ns, IOL = 48 mA, VIH = 2 V, VIL = 0.8 V | Higher drive and speed; consumes more ICC (19–32 mA vs. 9–14 mA) | Select when >50 MHz bus rates or heavier capacitive loads (>50 pF) are present |
Compared with SN74ALS257AN, SN74ALS257ADG4 offers surface-mount compatibility and smaller footprint; compared with SN74AS257D, it trades speed and drive strength for lower power consumption and broader legacy system compatibility.
Availability
SN74ALS257ADG4 is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy computer data buses, and embedded boot selection circuits requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS257ADG4 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 logic solutions for industrial, automotive, and communications markets.
The SN74ALS257ADG4 belongs to TI's legacy TTL logic portfolio, engineered for reliability and interoperability in bus-oriented digital systems where deterministic timing and 5 V compatibility remain critical.
FAQ
What is the function of the A/B pin on the SN74ALS257ADG4?
The A/B pin is a global select input that determines which of the two data sources (A or B) is routed to each of the four Y outputs. When A/B is low, all 1Y–4Y outputs reflect their respective A inputs (1A–4A); when high, they reflect their B inputs (1B–4B). This single-line control simplifies synchronization across all four channels in the SN74ALS257ADG4.
Does the SN74ALS257ADG4 support 3.3 V operation?
No, the SN74ALS257ADG4 is not rated for 3.3 V operation. Its recommended supply range is 4.5 V to 5.5 V, and absolute maximum VCC is 7 V. Input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) and output voltage levels (VOH ≥ 2.4 V at IOL = 12 mA) are specified only for 5 V operation. Using it with 3.3 V violates recommended conditions and risks unreliable switching in the SN74ALS257ADG4.
What is the maximum capacitive load the SN74ALS257ADG4 can drive reliably?
The SN74ALS257ADG4 is characterized for CL = 50 pF in switching specifications, with tPLH/tPHL guaranteed ≤12 ns under those conditions. While it can drive higher capacitance, timing margins degrade linearly beyond 50 pF. For loads exceeding 50 pF, derating analysis or empirical validation is required - the SN74ALS257ADG4 does not specify performance beyond this test condition.
Is the SN74ALS257ADG4 pin-compatible with the SN74LS257?
Yes, the SN74ALS257ADG4 is pin-compatible and functionally equivalent to the SN74LS257, sharing identical pinout, logic function, and DC electrical characteristics. However, the SN74ALS257ADG4 offers faster propagation delays (≤12 ns vs. ≤25 ns for LS) and lower power consumption, making it a direct performance upgrade within the same SOIC-D footprint.
What does the "G4" suffix indicate in SN74ALS257ADG4?
Per Texas Instruments' packaging nomenclature, the "G4" suffix denotes RoHS-compliant lead finish (NiPdAu) and moisture sensitivity level (MSL) 1 rating for the SOIC-D package. It confirms the SN74ALS257ADG4 meets JEDEC J-STD-020 requirements for reflow soldering at 260°C peak temperature without preconditioning.
SN74ALS257ADG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 2.6mA, 24mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74ALS257ADG4 FAQ
1.How can I place an order for SN74ALS257ADG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS257ADG4 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 SN74ALS257ADG4 reliable?
The price and inventory of SN74ALS257ADG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS257ADG4 is usually 5 days.
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Once your SN74ALS257ADG4 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 SN74ALS257ADG4?
For technical support, including SN74ALS257ADG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS257ADG4 requirements.
6.How does Aetrix verify that SN74ALS257ADG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS257ADG4 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 SN74ALS257ADG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS257ADG4?
All SN74ALS257ADG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS257ADG4, 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 SN74ALS257ADG4 part is unused and in its original packaging.
Return procedure for SN74ALS257ADG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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