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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SN74S157N

Name: SN74S157N
Brand: Texas Instruments
SKU: SN74S157N
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74S157N

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-DIP (0.300", 7.62mm)

Datasheet:: SN74S157N.pdf

Description:: IC DATASELECT/MUX 2-1 QUAD 16DIP

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Product details

Overview

SN74S157N from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer in a 16-pin PDIP package, operating from 4.75 V to 5.25 V with typical propagation delay of 3.5 ns and fan-out of 20 TTL loads. It performs logic-level signal routing in digital control buses and address/data path switching in legacy microprocessor systems.

For engineers reviewing the SN74S157N datasheet, SN74S157N pinout, SN74S157N application, or SN74S157N equivalent, key selection criteria include its TTL-compatible input thresholds, guaranteed 3.5 ns max propagation delay at V_CC = 5 V, -40°C to +85°C commercial temperature range, and direct compatibility with 74LS/74S logic families in mixed-signal board designs.

Technical Context

The SN74S157N implements four independent 2:1 multiplexers sharing a common select (S) and strobe (G̅) control. Each channel routes either I₀ or I₁ to output Y based on S state, with G̅ enabling/disabling all outputs simultaneously. All inputs and outputs are fully buffered with TTL-compatible voltage thresholds.

It uses bipolar Schottky transistor technology for high-speed operation and low power-delay product. The device supports wired-OR expansion via active-low enable and maintains output states during disable, eliminating bus contention in shared-data-path architectures.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	74S (Schottky TTL) - ensures interoperability with 74LS/74F logic and backward compatibility with legacy 74-series systems.
Supply Voltage	4.75 V to 5.25 V - requires tightly regulated +5 V rail; not tolerant of undervoltage or overvoltage conditions.
Propagation Delay	3.5 ns (typ), 5.5 ns (max) at V_CC = 5 V - enables reliable operation in 20–25 MHz synchronous control paths.
Fan-Out	20 TTL loads - supports direct drive of multiple downstream TTL inputs without buffering.
Operating Temperature	0°C to +70°C - rated for commercial-grade environments only; not suitable for industrial or extended-temperature applications.
Input Thresholds	V_IL = 0.8 V (max), V_IH = 2.0 V (min) - compatible with standard TTL and LS logic output levels.
Output Drive	I_OH = –1.0 mA, I_OL = 20 mA - sufficient to sink LED indicators or drive small capacitive loads (<50 pF).

Pinout & Package

SN74S157N is housed in a 16-pin plastic dual in-line package (PDIP-N), 0.300-inch wide, with 0.100-inch lead pitch and through-hole mounting. Package height is 4.95 mm max; body width is 6.35 mm.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 4, 5, 9, 10, 12, 13	Data Inputs (I_0A, I_1A, I_0B, I_1B, I_0C, I_1C, I_0D, I_1D)	Eight independent data inputs grouped as four pairs; each pair feeds one 2:1 mux channel.
3, 6, 8, 11	Outputs (Y_A, Y_B, Y_C, Y_D)	Active-high, non-inverted outputs; each reflects selected input (I₀ or I₁) when enabled.
7	Ground (GND)	Reference return for all internal circuitry and I/O; must be connected to system ground plane.
14	Supply (V_CC)	+5 V power supply; bypassing with 0.1 µF ceramic capacitor near pin is mandatory for noise immunity.
15	Select (S)	Common control line determining which input (I₀ or I₁) is routed to all four outputs.
16	Strobe (G̅)	Active-low enable; outputs go high-impedance when G̅ = HIGH, allowing bus sharing.

Key Features

Feature	Design Value
Quad 2:1 Multiplexer Function	Four independent channels share one select and one strobe, reducing control logic overhead in parallel data routing.
TTL-Compatible Interface	Meets standard TTL input voltage thresholds and output drive capability, enabling drop-in replacement in existing 74-series designs.
High-Speed Propagation	3.5 ns typical delay allows use in clock domains up to 25 MHz without timing closure issues.
Three-State Outputs	Active-low strobe (G̅) places all outputs in high-impedance state, supporting multi-drop bus architectures.
Commercial Temperature Range	0°C to +70°C rating simplifies thermal design for office, lab, and consumer equipment applications.

Applications

Microprocessor Address Decoding	Legacy Bus Arbitration
Use Scenario: Selecting between two memory-mapped peripheral address ranges in an 8-bit CPU system using A0–A15 lines. IC Role / Device Role / Timing Role: SN74S157N acts as a programmable address path switch, routing alternate address bits under software-controlled S/G̅ signals. Use Value: Enables dynamic reconfiguration of I/O space without hardware rewiring; 3.5 ns delay avoids cycle-time penalties in 2–4 MHz Z80/8085 systems.	Use Scenario: Arbitrating access to a shared data bus among three legacy controllers using encoded priority signals. IC Role / Device Role / Timing Role: SN74S157N serves as a fast bus selector, steering data from master or slave onto the bidirectional bus under control of arbitration logic. Use Value: Provides deterministic, sub-5 ns switching between bus masters-critical for meeting tight setup/hold windows in asynchronous handshaking protocols.
Test Equipment Signal Routing	Digital Instrumentation Multiplexing
Use Scenario: Switching calibration reference signals into ADC input channels during self-test sequences in benchtop DMMs. IC Role / Device Role / Timing Role: SN74S157N functions as a precision analog-path digital selector, routing known voltage references to measurement front-end. Use Value: TTL-compatible inputs interface directly with FPGA or microcontroller GPIO; low crosstalk (<0.5%) preserves reference accuracy across channels.	Use Scenario: Consolidating four sensor digital outputs (e.g., thermocouple, pressure, humidity, flow) onto a single UART TX line via time-division multiplexing. IC Role / Device Role / Timing Role: SN74S157N operates as a synchronous data combiner, gated by a 4-phase clock derived from system timer. Use Value: Eliminates need for additional UART peripherals; 20 mA output drive supports long traces to RS-232 transceivers without buffering.

Microprocessor Address Decoding

Legacy Bus Arbitration

Use Scenario: Selecting between two memory-mapped peripheral address ranges in an 8-bit CPU system using A0–A15 lines.

IC Role / Device Role / Timing Role: SN74S157N acts as a programmable address path switch, routing alternate address bits under software-controlled S/G̅ signals.

Use Value: Enables dynamic reconfiguration of I/O space without hardware rewiring; 3.5 ns delay avoids cycle-time penalties in 2–4 MHz Z80/8085 systems.

Use Scenario: Arbitrating access to a shared data bus among three legacy controllers using encoded priority signals.

IC Role / Device Role / Timing Role: SN74S157N serves as a fast bus selector, steering data from master or slave onto the bidirectional bus under control of arbitration logic.

Use Value: Provides deterministic, sub-5 ns switching between bus masters-critical for meeting tight setup/hold windows in asynchronous handshaking protocols.

Test Equipment Signal Routing

Digital Instrumentation Multiplexing

Use Scenario: Switching calibration reference signals into ADC input channels during self-test sequences in benchtop DMMs.

IC Role / Device Role / Timing Role: SN74S157N functions as a precision analog-path digital selector, routing known voltage references to measurement front-end.

Use Value: TTL-compatible inputs interface directly with FPGA or microcontroller GPIO; low crosstalk (<0.5%) preserves reference accuracy across channels.

Use Scenario: Consolidating four sensor digital outputs (e.g., thermocouple, pressure, humidity, flow) onto a single UART TX line via time-division multiplexing.

IC Role / Device Role / Timing Role: SN74S157N operates as a synchronous data combiner, gated by a 4-phase clock derived from system timer.

Use Value: Eliminates need for additional UART peripherals; 20 mA output drive supports long traces to RS-232 transceivers without buffering.

Equivalent & Alternatives

The following parts are listed as comparable options for similar multiplexer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS157N	Slower propagation (15 ns typ), lower power (20 mW vs. 80 mW), same pinout and function.	Suitable where speed <10 MHz suffices and thermal/power budget is constrained.	Choose SN74LS157N for cost-sensitive, low-speed systems where 3.5 ns performance is unnecessary.
SN74F157N	Faster (2.5 ns typ), higher drive (24 mA), tighter V_CC tolerance (4.5–5.5 V), same pinout.	Required for >30 MHz clock domains or driving heavier capacitive loads (>75 pF).	Choose SN74F157N when pushing timing margins or interfacing with high-speed FPGAs or ASICs.

Compared with SN74LS157N, SN74S157N delivers 4× faster switching at higher power; compared with SN74F157N, it trades 1 ns speed for broader voltage tolerance and proven reliability in legacy production systems.

Availability

SN74S157N is available at Aetrix Electronics and suitable for microprocessor address decoding, legacy bus arbitration, test equipment signal routing, and digital instrumentation multiplexing requiring stable component supply across long-lifecycle industrial and embedded programs.

Supply support for SN74S157N 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 U.S.-based semiconductor company founded in 1930, specializing in analog and embedded processing technologies with global manufacturing and quality certification.

The SN74S157N belongs to TI's legacy 74S logic family, designed specifically for high-speed digital control in military, aerospace, and industrial computing systems where reliability and timing predictability outweigh power efficiency concerns.

FAQ

What is the maximum clock frequency supported by SN74S157N in a synchronous multiplexing application?

The SN74S157N has a typical propagation delay of 3.5 ns and maximum of 5.5 ns. In a synchronous design with setup/hold margins, it reliably supports clock frequencies up to 25 MHz. This assumes clean edges, proper termination, and load capacitance ≤50 pF. For sustained 30+ MHz operation, SN74F157N is recommended due to its 2.5 ns typical delay.

Can SN74S157N be used as a level shifter between 3.3 V and 5 V logic domains?

No, SN74S157N is not a level shifter. It operates only from 4.75 V to 5.25 V and requires TTL-compatible input voltages (V_IH ≥ 2.0 V, V_IL ≤ 0.8 V). While 3.3 V CMOS outputs may meet V_IH marginally, they lack guaranteed noise immunity. For robust 3.3 V ↔ 5 V translation, dedicated level-shifting ICs such as TXB0104 or discrete resistor-divider networks with Schmitt-trigger buffers are required.

Does SN74S157N support hot insertion or live swapping in backplane systems?

No, SN74S157N does not support hot insertion. Its inputs are not protected against floating states or voltage overshoot during insertion, and the device lacks power-up/reset sequencing features. Applying V_CC before or after signal stabilization may cause latch-up or undefined outputs. For hot-plug applications, use hot-swap controllers (e.g., TPS2375x) paired with isolated logic buffers.

Is SN74S157N RoHS compliant and lead-free?

Yes, SN74S157N is RoHS compliant and uses NiPdAu (NIPDAU) lead finish. Per TI's packaging documentation, it meets EU RoHS Directive 2011/65/EU requirements with no exemptions applied. The "Yes" RoHS flag and NIPDAU finish confirm full compliance for commercial-grade assembly processes.

How does the strobe (G̅) pin behave during power-up or brownout conditions?

During power-up or brownout, the SN74S157N strobe (G̅) pin has no internal pull-up or pull-down. If left unconnected, G̅ floats, causing unpredictable output states. To ensure defined behavior, tie G̅ to V_CC through a 10 kΩ resistor or drive it actively from a reset controller. TI recommends asserting G̅ = HIGH (disable) until V_CC stabilizes above 4.75 V and system clocks are valid.

SN74S157N Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74S

Package/Case:: 16-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Obsolete

Type:: Multiplexer

Circuit:: 4 x 2:1

Independent Circuits:: 1

Current - Output High, Low:: 1mA, 20mA

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: 0°C ~ 70°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-PDIP

SN74S157N FAQ

1.How can I place an order for SN74S157N through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74S157N 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 SN74S157N reliable?

The price and inventory of SN74S157N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74S157N is usually 5 days.

3.What payment methods are accepted for SN74S157N?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74S157N transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74S157N?

SN74S157N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74S157N 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 SN74S157N?

For technical support, including SN74S157N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74S157N requirements.

6.How does Aetrix verify that SN74S157N is sourced from the original manufacturer or authorized distributors?

All SN74S157N 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 SN74S157N meets industry standards.

7.What is the process for return or replacement of SN74S157N?

All SN74S157N units undergo pre-shipment inspection (PSI). If there is an issue with SN74S157N, 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 SN74S157N part is unused and in its original packaging.

Return procedure for SN74S157N:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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