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Texas Instruments SN74ALS157ANSR
- Part No.:
- SN74ALS157ANSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS157ANSR.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,342
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Product details
Overview
SN74ALS157ANSR from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer IC with true-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 parameters: VCC = 4.5–5.5 V, propagation delay tPLH/tPHL ≤ 14 ns (A/B→Y), IOL = 4 mA, operating temperature 0°C to 70°C, SOP-16 package.
For engineers reviewing the SN74ALS157ANSR datasheet, SN74ALS157ANSR pinout, SN74ALS157ANSR application, or SN74ALS157ANSR equivalent, this page delivers verified functional identity, validated timing specs, confirmed SOP-16 pin mapping, and real-world use cases in legacy TTL bus interfacing, address/data path selection, and synchronous logic control - all derived from TI's official SDAS081C datasheet and packaging addendum.
Technical Context
The SN74ALS157ANSR implements four independent 2:1 multiplexers in a single IC, each selecting between corresponding bits of two 4-bit inputs (1A/1B through 4A/4B) using a shared A/B select line and active-low enable (G). Its internal architecture includes inverters and drivers to ensure full logic-level buffering at both inputs and outputs, eliminating fanout limitations typical of unbuffered TTL.
All outputs present true (non-inverted) data, distinguishing it from the SN74ALS158 family. The device operates strictly as a combinatorial logic element with no internal latching or clocking - propagation delays are specified per input-to-output path (A/B→Y, A/B→Y, G→Y), and no 3-state functionality is supported.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures compatibility with standard 5 V TTL supply rails and margin against ripple or droop. |
| Propagation Delay (A/B → Y) | Max 24 ns at VCC = 4.5 V, CL = 50 pF - defines worst-case timing budget for data path selection in synchronous bus arbitration. |
| Output Drive (IOL) | 4 mA at VOL ≤ 0.4 V - supports direct interface to standard TTL loads without external pull-ups or buffers. |
| Input Thresholds (VIH/VIL) | VIH ≥ 2.0 V, VIL ≤ 0.8 V - guarantees reliable recognition of TTL logic levels across temperature and voltage variation. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded control, industrial PLC backplanes, and instrumentation interfaces. |
| Supply Current (ICC) | 6–11 mA typical at VCC = 5.5 V - enables accurate power budgeting in multi-device TTL subsystems. |
Pinout & Package
SOP-16 (NS) package: 16-pin small-outline plastic package with 1.27 mm pitch, 10.4 mm × 5.3 mm body, 2.00 mm max height, and moisture sensitivity level (MSL) 1 - suitable for standard reflow assembly without baking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1A, 2A, 3A, 4A | Data Input A (bit 1–4) | First 4-bit source channel; driven high/low to feed selected word into multiplexer. |
| 1B, 2B, 3B, 4B | Data Input B (bit 1–4) | Second 4-bit source channel; alternative input set selected when A/B = HIGH. |
| 1Y, 2Y, 3Y, 4Y | True Output (bit 1–4) | Buffered, non-inverted outputs delivering selected A or B bit values. |
| A/B | Select Control | Global 2:1 selector: LOW selects A inputs, HIGH selects B inputs. |
| G | Strobe Enable | Active-LOW gate: outputs go LOW when G = HIGH; outputs reflect selection when G = LOW. |
| VCC | Power Supply | Positive supply terminal (Pin 16); must be decoupled locally for noise immunity. |
| GND | Ground Reference | Signal and power return (Pin 8); requires low-impedance connection to system ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| True-output logic | Delivers non-inverted data (vs. SN74ALS158), simplifying signal polarity planning in bus arbitration paths. |
| Buffered inputs and outputs | Enables direct fanout to ≥10 standard TTL loads without external drivers or level-shifting. |
| Low propagation delay | Typical tPLH = 9 ns (A/B→Y) at VCC = 5 V - supports sub-100 MHz data selection cycles in legacy systems. |
| TTL-compatible thresholds | VIH = 2.0 V / VIL = 0.8 V ensures interoperability with 74LS, 74F, and microcontroller GPIOs without level translation. |
| SOP-16 RoHS-compliant packaging | NiPdAu lead finish, MSL-1 rating, and tape-and-reel delivery (2000 pcs/reel) support automated SMT manufacturing. |
Applications
| Legacy Bus Arbitration | Microcontroller Address/Data Multiplexing |
|---|---|
Use Scenario: Selecting between two memory banks or peripheral data buses sharing a common 4-bit data path in an 8-bit microprocessor system (e.g., Z80 or 8085). IC Role / Device Role / Timing Role: Quad 2:1 data selector enabling dynamic routing of nibble-wide signals under software-controlled A/B and G lines. Use Value: Eliminates need for discrete logic gates or PLD-based routing, reducing component count and PCB area in space-constrained industrial controllers. |
Use Scenario: Isolating and selecting between two sets of I/O port lines (e.g., GPIO expansion vs. sensor interface) on an 8-bit MCU with limited pin count. IC Role / Device Role / Timing Role: Combinatorial multiplexer providing deterministic, glitch-free nibble selection synchronized to MCU write strobes. Use Value: Enables dual-function I/O without hardware redesign; supports field-upgradable peripheral configurations via firmware-selectable A/B state. |
| Digital Test Equipment Signal Routing | Industrial PLC Backplane Interface |
Use Scenario: Switching calibration reference signals or test patterns into a 4-bit ADC/DAC channel during automated functional testing. IC Role / Device Role / Timing Role: Precision signal selector with guaranteed timing margins (tPLH ≤ 24 ns) for repeatable test sequence execution. Use Value: Ensures measurement repeatability by eliminating analog switch settling time and charge injection artifacts inherent in CMOS alternatives. |
Use Scenario: Managing parallel status/data handshaking between CPU module and I/O carrier boards in modular PLC chassis. IC Role / Device Role / Timing Role: Robust TTL-level multiplexer tolerant of industrial EMI, supporting reliable 4-bit handshake signal routing over backplane traces. Use Value: Maintains signal integrity across noisy environments due to buffered drive strength (IOL = 4 mA) and noise-immune input thresholds. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar data selector applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS157AN | Same logic function and electrical specs, but in 16-pin PDIP (N) package with through-hole mounting and no MSL rating. | Preferred for prototyping, manual assembly, or legacy board repair where SOP footprint is unavailable. | Select SN74ALS157AN when hand-soldering or socket-based validation is required; SN74ALS157ANSR is optimal for volume SMT production. |
| SN74AS157NSR | Faster propagation (tPLH ≤ 6 ns), higher ICC (17.5–28 mA), and tighter VIH/VIL (VIH = 2.0 V, VIL = 0.8 V same), but identical pinout and SOP-16 package. | Better suited for high-speed timing-critical paths where <10 ns delay is mandatory, at cost of increased power draw. | Choose SN74AS157NSR only if measured path delay exceeds SN74ALS157ANSR's 24 ns max; otherwise, ALS version offers superior power efficiency. |
Compared with SN74ALS157AN and SN74AS157NSR, the SN74ALS157ANSR delivers the optimal balance of legacy TTL compatibility, SOP-16 manufacturability, and 24 ns worst-case delay - making it the preferred choice for cost-sensitive, medium-speed industrial control upgrades where power efficiency and RoHS compliance are prioritized over maximum speed.
Availability
SN74ALS157ANSR is available at Aetrix Electronics and suitable for industrial control panels, legacy test equipment refurbishment, and microcontroller-based peripheral interface designs requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74ALS157ANSR 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 with broad industrial, automotive, and aerospace qualification.
The SN74ALS157ANSR belongs to TI's 74ALS advanced low-power Schottky logic family, designed specifically for high-speed, low-power TTL-compatible digital systems requiring robust noise immunity and direct replacement of older 74S/74LS devices.
FAQ
What logic family does the SN74ALS157ANSR belong to, and how does it differ from standard TTL?
The SN74ALS157ANSR belongs to the 74ALS (Advanced Low-Power Schottky) logic family. It differs from standard TTL by offering lower power consumption (ICC = 6–11 mA vs. 74S's ~20 mA) while maintaining compatible voltage thresholds (VIH = 2.0 V, VIL = 0.8 V) and improved speed over 74LS. Unlike 74F or 74AS, it prioritizes power efficiency over raw speed - confirmed by its 24 ns max propagation delay and 4 mA output drive in the SN74ALS157ANSR datasheet.
Does the SN74ALS157ANSR support 3-state outputs, and what happens when the G input is HIGH?
No, the SN74ALS157ANSR does not support 3-state outputs. When G is HIGH, all four outputs (1Y–4Y) are forced LOW regardless of A/B or data inputs - this is a hard-wired active-LOW enable, not a high-impedance state. This behavior is explicitly defined in the FUNCTION TABLE of the SN74ALS157ANSR datasheet and distinguishes it from 3-state multiplexers like the 74LS257.
What is the exact pin 1 location and orientation for the SN74ALS157ANSR SOP-16 package?
Per TI's NS0016A package drawing and tape-and-reel specification, SN74ALS157ANSR uses SOP-16 (NS) with pin 1 located at the top-left corner of the package, identified by a beveled edge or dot marking. The pin 1 quadrant in tape is Q1, and the device follows standard SOP numbering: pins 1–8 down the left side, 9–16 up the right side, with GND at pin 8 and VCC at pin 16 - fully validated from TI's PACKAGE OUTLINE and TAPE AND REEL INFORMATION documents.
Can the SN74ALS157ANSR be used as a direct replacement for the SN74LS157 in existing designs?
Yes, the SN74ALS157ANSR is a pin-compatible and functionally equivalent drop-in replacement for SN74LS157 in SOP-16 layouts, with identical pinout, true-output logic, and compatible VIH/VIL thresholds. It improves upon LS with lower ICC (6–11 mA vs. 19 mA), faster propagation (24 ns max vs. 34 ns), and enhanced noise margin - all confirmed in TI's SDAS081C datasheet comparison tables for ALS vs. LS families.
What are the absolute maximum ratings for the SN74ALS157ANSR, and why do they matter for design margining?
The SN74ALS157ANSR has absolute maximum ratings of VCC ≤ 7 V, VI ≤ 7 V, and storage temperature −65°C to +150°C. These define stress limits beyond which permanent damage may occur; they are not operational conditions. Designers must ensure operating VCC stays within 4.5–5.5 V and inputs remain within −0.5 V to VCC+0.5 V to avoid latch-up or degradation - critical for reliability in industrial environments where transient surges or thermal cycling occur.
SN74ALS157ANSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SO
SN74ALS157ANSR FAQ
1.How can I place an order for SN74ALS157ANSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS157ANSR 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 SN74ALS157ANSR reliable?
The price and inventory of SN74ALS157ANSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS157ANSR is usually 5 days.
3.What payment methods are accepted for SN74ALS157ANSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS157ANSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS157ANSR?
SN74ALS157ANSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS157ANSR 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 SN74ALS157ANSR?
For technical support, including SN74ALS157ANSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS157ANSR requirements.
6.How does Aetrix verify that SN74ALS157ANSR is sourced from the original manufacturer or authorized distributors?
All SN74ALS157ANSR 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 SN74ALS157ANSR meets industry standards.
7.What is the process for return or replacement of SN74ALS157ANSR?
All SN74ALS157ANSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS157ANSR, 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 SN74ALS157ANSR part is unused and in its original packaging.
Return procedure for SN74ALS157ANSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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