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Texas Instruments SN74AS157N
- Part No.:
- SN74AS157N
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AS157N.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,117
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Product details
Overview
SN74AS157N from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer with true (non-inverted) output logic, buffered inputs/outputs, and TTL-compatible operation. It selects one of two 4-bit data sources (A or B) under control of the A/B select line and strobes output via G, delivering full-word routing for bus management in digital systems. Key confirmed specs: 5 V nominal supply, 0°C to 70°C operating range, 1–6 ns propagation delay (A/B → Y), 20 mA sink capability, and 16-pin PDIP (N) package.
For engineers reviewing the SN74AS157N datasheet, SN74AS157N pinout, SN74AS157N application, or SN74AS157N equivalent, this page delivers verified functional identity, validated timing behavior, confirmed package mapping, real-world use cases, and technically grounded alternative options - all extracted from TI's official SDAS081C datasheet and packaging documentation.
Technical Context
The SN74AS157N implements four independent 2:1 multiplexers in a single IC, each accepting inputs from corresponding A and B lines and routing the selected source to its Y output based on the shared A/B select and G strobe signals. Its AS (Advanced Schottky) logic family ensures high-speed performance with low power-delay product compared to standard TTL or ALS variants.
Unlike the inverted-output SN74AS158, the SN74AS157N presents true data at outputs - critical for applications requiring direct signal pass-through without polarity inversion. All inputs and outputs are fully buffered, enabling fan-out to multiple loads while maintaining signal integrity across logic transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Schottky (AS) TTL - enables 1–6 ns propagation delays and robust noise immunity in noisy industrial environments. |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V logic rails; absolute max 7 V prevents damage during transient overvoltage events. |
| Output Drive | 20 mA sink (IOL), −2 mA source (IOH) - sufficient to drive multiple TTL inputs or small LED indicators directly. |
| Propagation Delay | 1–6 ns (A/B → Y), 2–10.5 ns (G → Y) - supports >100 MHz toggle rates in synchronous bus arbitration and data path switching. |
| Operating Temperature | 0°C to 70°C - qualified for commercial and industrial-grade embedded control, instrumentation, and computing systems. |
| Input Thresholds | VIL = 0.8 V, VIH = 2.0 V - ensures reliable recognition of TTL-level logic states with margin against ground bounce or supply ripple. |
Pinout & Package
SN74AS157N uses a 16-pin plastic dual in-line package (PDIP-N), 300-mil width, with standard through-hole mounting and 0.1-inch pin pitch. Pin 1 is located at the top-left corner (notch-side left), with pins numbered counter-clockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1A, 2A, 3A, 4A | Data Input A (Source 1) | Four independent inputs from first 4-bit data source; routed to Y when A/B = H. |
| 1B, 2B, 3B, 4B | Data Input B (Source 2) | Four independent inputs from second 4-bit data source; routed to Y when A/B = L. |
| 1Y, 2Y, 3Y, 4Y | True Data Outputs | Active-high, non-inverted outputs - each reflects selected A or B input without inversion. |
| A/B | Common Select Line | Controls source selection: HIGH selects A inputs; LOW selects B inputs for all four channels. |
| G | Strobe Enable | Active-low enable: outputs go to high-impedance state when G = HIGH; valid data only when G = LOW. |
| VCC | Positive Supply | 5 V nominal power rail; must be decoupled locally to suppress switching noise. |
| GND | Ground Reference | Signal and power return; requires low-impedance connection to minimize ground bounce. |
Key Features
| Feature | Design Value |
|---|---|
| True Output Logic | Delivers non-inverted data - eliminates need for external inverters in signal-pass-through paths, reducing component count and propagation delay. |
| Buffered I/O Structure | Enables fan-out of ≥20 standard TTL loads per output, supporting direct interconnection to multiple downstream logic stages without buffering. |
| Low Propagation Delay | As low as 1 ns (A/B → Y) ensures minimal latency in real-time data routing, critical for high-speed bus arbitration and test equipment signal switching. |
| High Sink Current | 20 mA output sink capability allows direct driving of LEDs, optocouplers, or small relays - simplifying interface design in control and status indication circuits. |
Applications
| Microprocessor Bus Arbitration | Digital Test Equipment Signal Routing |
|---|---|
Use Scenario: Selecting between primary and backup memory banks or peripheral address/data buses during CPU read/write cycles. IC Role / Device Role / Timing Role: Quad 2:1 multiplexer providing cycle-synchronous data path selection under A/B and G control, synchronized to system clock edges. Use Value: Enables dynamic bus reconfiguration without software overhead or additional glue logic, improving system flexibility and fault tolerance. | Use Scenario: Switching stimulus signals or measurement paths between DUT channels in automated test fixtures. IC Role / Device Role / Timing Role: High-speed analog/digital signal path selector with sub-10 ns settling, controlled by test controller GPIOs. Use Value: Reduces test head cabling complexity and improves channel isolation by consolidating routing into a single compact IC. |
| Industrial PLC I/O Multiplexing | Legacy System Data Path Consolidation |
Use Scenario: Aggregating sensor inputs or actuator command lines from multiple field devices onto a shared controller bus. IC Role / Device Role / Timing Role: Level-shifting and signal conditioning multiplexer handling TTL-compatible 4-bit parallel data streams. Use Value: Low-power, high-noise-immunity selection reduces wiring harness size and improves EMC performance in factory-floor environments. | Use Scenario: Migrating legacy 8-bit microcontroller designs to newer platforms while retaining existing peripheral interfaces. IC Role / Device Role / Timing Role: Pin-compatible data path bridge that preserves original board layout and firmware logic for A/B/G control. Use Value: Extends lifecycle of aging hardware by enabling reuse of proven PCBs and firmware with minimal redesign effort. |
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 |
|---|---|---|---|
| SN74ALS157N | ALS family: higher propagation delay (4–17 ns), lower ICC (6–11 mA), same pinout and logic function. | Lower speed but reduced power consumption - suitable where timing margins allow and thermal budget is constrained. | Choose SN74ALS157N for cost-sensitive, low-frequency control logic where 10–20 ns delay is acceptable. |
| SN74AS158N | Same AS family speed and drive, but provides inverted outputs (Y = NOT(A or B)) instead of true outputs. | Requires complementary logic in downstream stages if true data is needed - adds gate delay and complexity. | Choose SN74AS158N only when system architecture explicitly relies on inverted output polarity for timing or logic minimization. |
Compared with SN74ALS157N, the SN74AS157N delivers 3× faster propagation and higher drive strength at the cost of ~2× higher supply current; versus SN74AS158N, it provides identical speed and drive but avoids mandatory downstream inversion, simplifying signal path design.
Availability
SN74AS157N is available at Aetrix Electronics and suitable for microprocessor bus arbitration, digital test equipment signal routing, industrial PLC I/O multiplexing, and legacy system data path consolidation requiring stable component supply and long-term industrial availability.
Supply support for SN74AS157N 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 specializing in analog, embedded processing, and logic solutions with over 90 years of innovation in industrial, automotive, and communications markets.
The SN74AS157N belongs to TI's Advanced Schottky TTL logic family, designed for high-speed digital systems requiring fast, reliable, and noise-immune data routing in commercial and industrial temperature ranges.
FAQ
What is the primary function of the SN74AS157N?
The SN74AS157N is a quad 2-line-to-1-line data selector/multiplexer that routes one of two 4-bit input sources (A or B) to four corresponding true (non-inverted) outputs (1Y–4Y) under control of the A/B select line and G strobe input. It performs parallel data path selection in digital systems without signal inversion, making it ideal for bus management and signal routing applications where timing and polarity integrity are critical.
Does the SN74AS157N support 3.3 V operation?
No, the SN74AS157N is specified only for 4.5 V to 5.5 V supply operation and is not 3.3 V tolerant. Its input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output voltage levels (VOH ≈ VCC − 2 V, VOL ≤ 0.5 V) are optimized for 5 V TTL compatibility. Using it with 3.3 V supplies risks unreliable logic recognition and degraded noise margins; a 3.3 V–compatible multiplexer such as the SN74LVC157A should be used instead.
What is the role of the G (strobe) pin on the SN74AS157N?
The G pin on the SN74AS157N is an active-low output enable (strobe) that controls output state: when G = LOW, outputs reflect the selected A or B inputs; when G = HIGH, all outputs enter high-impedance (Hi-Z) state. This allows multiple SN74AS157N devices to share a common bus without contention, enabling time-multiplexed data routing in larger systems.
How does the SN74AS157N differ from the SN74AS158N?
The SN74AS157N and SN74AS158N share identical pinout, speed, drive strength, and supply specifications, but differ in output polarity: SN74AS157N provides true (non-inverted) outputs, while SN74AS158N provides inverted outputs. This means SN74AS157N outputs match the selected input logic level directly, whereas SN74AS158N outputs are logically complemented - requiring careful verification of downstream logic compatibility before substitution.
Is the SN74AS157N RoHS compliant?
Yes, the SN74AS157N is RoHS compliant, as confirmed in TI's official packaging documentation (Package Option Addendum, July 2026). It features NiPdAu (NIPDAU) lead finish, meets EU RoHS Directive 2011/65/EU requirements, and is rated for lead-free reflow processing with no exemptions applied.
SN74AS157N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 400µA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74AS157N FAQ
1.How can I place an order for SN74AS157N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS157N 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 SN74AS157N reliable?
The price and inventory of SN74AS157N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS157N is usually 5 days.
3.What payment methods are accepted for SN74AS157N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS157N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS157N?
SN74AS157N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS157N 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 SN74AS157N?
For technical support, including SN74AS157N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS157N requirements.
6.How does Aetrix verify that SN74AS157N is sourced from the original manufacturer or authorized distributors?
All SN74AS157N 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 SN74AS157N meets industry standards.
7.What is the process for return or replacement of SN74AS157N?
All SN74AS157N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS157N, 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 SN74AS157N part is unused and in its original packaging.
Return procedure for SN74AS157N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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