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Texas Instruments SN74AS257DRG4
- Part No.:
- SN74AS257DRG4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AS257DRG4.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,536
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Product details
Overview
SN74AS257DRG4 from Texas Instruments is a 4-bit dual 2-line-to-1 data selector/multiplexer with 3-state outputs, designed for bus-organized systems. It features 16-pin SOIC (D) package, operates from 0°C to 70°C, supports 4.5–5.5 V supply, and delivers ±15 mA high-level and 48 mA low-level output drive. It enables bidirectional bus interface in high-performance digital logic systems.
For engineers reviewing the SN74AS257DRG4 datasheet, SN74AS257DRG4 pinout, SN74AS257DRG4 application, or SN74AS257DRG4 equivalent, key selection criteria include its 3-state bus interface capability, sub-6 ns propagation delay (A/B → Y), 7.5 ns enable/disable timing, and compatibility with TTL/LS logic families in legacy industrial control and test equipment designs.
Technical Context
The SN74AS257DRG4 implements a dual 2:1 multiplexer architecture with independent A/B select inputs per 4-bit channel and a shared output-enable (OE) control. Its 3-state outputs isolate data lines when OE is high, preventing bus contention during multi-source arbitration.
It uses advanced Schottky (AS) bipolar technology to achieve faster switching than ALS variants-tPHL/tPLH ≤ 6 ns (A/B → Y), tPZL ≤ 9.5 ns (OE → Y), and ICC ≤ 31.9 mA (outputs disabled at VCC = 5.5 V). Input thresholds (VIH = 2 V, VIL = 0.8 V) ensure robust noise immunity in mixed-logic environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | 4-bit dual 2-line-to-1 data selector with 3-state outputs - enables time-shared routing of two 4-bit data sources onto one 4-bit bus |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V TTL/LS power rails without regulation overhead |
| Propagation Delay | 1–5.5 ns (A/B → Y) - supports >150 MHz data throughput in synchronous bus applications |
| Output Drive | −15 mA (IOH), 48 mA (IOL) - directly drives multiple TTL loads without external buffers |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade industrial control and instrumentation systems |
| Package | 16-pin SOIC (D), 3.9 mm × 9.9 mm - surface-mount compatible with automated PCB assembly and space-constrained layouts |
| Logic Family | TTL-compatible AS series - provides Schottky-clamped speed advantage over standard 74LS while maintaining pinout and voltage compatibility |
Pinout & Package
SN74AS257DRG4 is housed in a 16-pin small-outline integrated circuit (SOIC-D) package with 1.27 mm pitch, 3.9 mm body width, and 9.9 mm length. Pin 1 is marked by a beveled corner or dot; leads are gull-wing shaped for reflow soldering.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4 5, 6, 7, 8 13, 14, 15, 16 |
Data Inputs (1A/1B, 2A/2B, 3A/3B, 4A/4B) | Four independent dual-input channels - each pair selects between two 4-bit parallel data sources |
| 9, 10, 11, 12 | 3-State Outputs (1Y, 2Y, 3Y, 4Y) | Active-low enabled; high-impedance state prevents bus loading when OE = HIGH |
| 15 | Output Enable (OE) | Active-low global control - disables all outputs simultaneously for bus arbitration |
| 3 | Select Control (A/B) | Common select line for all four channels - determines whether A or B input appears at corresponding Y output |
| 8 | GND | Signal reference ground - must be low-inductance connection to minimize switching noise |
| 16 | VCC | +5 V power supply - requires local 0.1 µF ceramic decoupling adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| 3-State Bus Interface | Enables direct connection to shared data buses without external isolation logic or pull-up resistors |
| Sub-6 ns Propagation Delay | Supports high-speed data routing in real-time control loops and digital test instrumentation |
| High Output Drive Strength | ±15 mA IOH / 48 mA IOL allows fan-out to ≥10 standard TTL loads without buffering |
| AS-Series Speed Advantage | Up to 2× faster than 74ALS257A with identical pinout and logic function - drop-in performance upgrade |
| SOIC-D Packaging | Industry-standard 16-pin surface-mount footprint simplifies layout, reduces board area, and supports automated assembly |
Applications
| Industrial PLC Backplane | Digital Test Equipment |
|---|---|
|
Use Scenario: Multiplexing sensor data streams from multiple I/O modules onto a central processor bus in programmable logic controllers. IC Role / Device Role: Dual 4-bit data selector enabling time-sliced access to distributed analog/digital input cards. Use Value: Eliminates need for discrete gating logic; 3-state outputs prevent bus contention during module hot-swap or fault isolation. |
Use Scenario: Routing stimulus signals from multiple pattern generators to device-under-test (DUT) pins in automated test systems. IC Role / Device Role: High-speed signal path selector coordinating timing-critical vector delivery across parallel DUT interfaces. Use Value: Sub-6 ns propagation ensures minimal skew between stimulus channels; ±15 mA drive sustains signal integrity into 50 Ω loads. |
| Legacy Computer Bus Arbitration | Embedded Instrumentation Front-End |
|
Use Scenario: Managing shared memory or peripheral address/data buses among CPU, DMA controller, and co-processor in vintage computing platforms. IC Role / Device Role: Bidirectional bus multiplexer resolving contention between concurrent bus masters using OE-controlled tristate isolation. Use Value: Pin-compatible replacement for 74LS257 with 2× speed margin - extends functional life of aging hardware without redesign. |
Use Scenario: Selecting between calibration reference voltages and sensor inputs in precision measurement front-ends for oscilloscopes or DMMs. IC Role / Device Role: Low-noise analog multiplexing stage where fast settling and minimal crosstalk are critical for ADC accuracy. Use Value: 0.5 V VOL at 48 mA ensures clean logic-level transitions into downstream comparators or sample-hold circuits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar data selector/multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS257ADR | Slower propagation (≤10 ns A/B→Y), lower drive (−2.6 mA IOH, 24 mA IOL), higher ICC (≤14 mA disabled) | Suitable for cost-sensitive, lower-speed legacy systems where timing margin is ample | Choose for backward compatibility in existing ALS-based designs where speed upgrade is unnecessary |
| SN74AS257N | Identical electrical specs but in 16-pin PDIP (N) through-hole package; no RoHS exemption required | Better suited for prototyping, repair, or through-hole production where SOIC reflow is unavailable | Choose when manual soldering, socketing, or legacy assembly infrastructure mandates DIP format |
Compared with SN74ALS257ADR, SN74AS257DRG4 delivers 40% faster switching and 2× output current, enabling tighter timing budgets and reduced buffer count; versus SN74AS257N, it offers smaller footprint and automated assembly compatibility while retaining identical logic behavior and thermal performance.
Availability
SN74AS257DRG4 is available at Aetrix Electronics and suitable for industrial control systems, digital test instrumentation, legacy computer bus arbitration, and embedded instrumentation front-end designs requiring stable component supply and long-term obsolescence management.
Supply support for SN74AS257DRG4 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 ICs with broad industrial, automotive, and aerospace qualification.
The SN74AS257DRG4 belongs to TI's 74AS logic family, engineered for high-speed digital signal routing in mission-critical industrial and test equipment where reliability and timing predictability outweigh power efficiency concerns.
FAQ
What is the maximum operating frequency supported by SN74AS257DRG4?
The SN74AS257DRG4 does not specify a maximum clock frequency in its datasheet because it is a combinational logic device without internal clocking. However, its propagation delay (tPLH/tPHL ≤ 5.5 ns) and enable/disable times (tPZL ≤ 9.5 ns) support reliable operation in systems with data rates up to ~150 MHz under typical load conditions (CL = 50 pF, R1/R2 = 500 Ω). System-level timing must account for board trace delays and fan-out loading. The SN74AS257DRG4 is optimized for asynchronous bus multiplexing rather than synchronous clocked operation.
Does SN74AS257DRG4 support mixed-voltage interfacing with 3.3 V logic?
No, SN74AS257DRG4 is a 5 V-only TTL-family device with VIH = 2.0 V minimum and VIL = 0.8 V maximum, and it lacks 3.3 V tolerant inputs. Driving its inputs from 3.3 V logic may result in marginal or unreliable high-level recognition, especially over temperature and process variation. Interfacing with 3.3 V systems requires level-shifting circuitry or a 3.3 V–compatible multiplexer such as the SN74LVC257. The SN74AS257DRG4 itself must be powered at 4.5–5.5 V and is not designed for mixed-supply operation.
What is the meaning of "DRG4" in SN74AS257DRG4?
The suffix "DRG4" in SN74AS257DRG4 denotes a specific packaging and environmental configuration: "D" indicates 16-pin SOIC package, "R" signifies tape-and-reel packaging (2000 units per reel), and "G4" specifies RoHS-compliant lead finish (NiPdAu) with Level-1 moisture sensitivity rating (MSL-1, unlimited floor life at ≤30°C/60% RH). This marking aligns with Texas Instruments' standardized orderable part numbering convention for active production parts, distinguishing it from tube-packaged (e.g., SN74AS257D) or non-RoHS variants.
Can SN74AS257DRG4 replace SN74LS257 in an existing design?
Yes, SN74AS257DRG4 is a pin-compatible and functionally identical drop-in replacement for SN74LS257, offering identical pinout, logic truth table, and DC electrical characteristics (VIH/VIL, VOH/VOL). Its key advantage is significantly improved AC performance: propagation delay is reduced from ~15 ns (LS) to ≤5.5 ns (AS), and output drive increases from ±0.4 mA/8 mA to −15 mA/48 mA. No PCB changes are required, but verify that the higher ICC (up to 31.9 mA) and faster edge rates do not induce excessive noise or violate existing power delivery margins in the SN74AS257DRG4 implementation.
Is SN74AS257DRG4 suitable for use in automotive applications?
No, SN74AS257DRG4 is rated for 0°C to 70°C operation and is classified as a commercial-grade device, not qualified to AEC-Q100 or automotive temperature ranges (−40°C to 125°C). It lacks automotive-specific reliability testing, qualification documentation, and extended temperature characterization. For automotive applications requiring a 4-bit dual 2:1 multiplexer, consider TI's automotive-qualified alternatives such as the SN74LV257A-Q1 (−40°C to 125°C, LV-CMOS) or consult TI's automotive logic portfolio. The SN74AS257DRG4 is intended for industrial, test, and commercial equipment only.
SN74AS257DRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 15mA, 48mA
- 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
SN74AS257DRG4 FAQ
1.How can I place an order for SN74AS257DRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS257DRG4 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 SN74AS257DRG4 reliable?
The price and inventory of SN74AS257DRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS257DRG4 is usually 5 days.
3.What payment methods are accepted for SN74AS257DRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS257DRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS257DRG4?
SN74AS257DRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS257DRG4 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 SN74AS257DRG4?
For technical support, including SN74AS257DRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS257DRG4 requirements.
6.How does Aetrix verify that SN74AS257DRG4 is sourced from the original manufacturer or authorized distributors?
All SN74AS257DRG4 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 SN74AS257DRG4 meets industry standards.
7.What is the process for return or replacement of SN74AS257DRG4?
All SN74AS257DRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS257DRG4, 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 SN74AS257DRG4 part is unused and in its original packaging.
Return procedure for SN74AS257DRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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