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

Texas Instruments SN74LS151D

Name: SN74LS151D
Brand: Texas Instruments
SKU: SN74LS151D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74LS151D

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-SOIC (0.154", 3.90mm Width)

Datasheet:: SN74LS151D.pdf

Description:: IC MULTIPLEXER 1 X 8:1 16SOIC

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Product details

Overview

SN74LS151D from Texas Instruments is a 8-line to 1-line TTL multiplexer with active-low enable (G̅), three select inputs (A, B, C), and complementary outputs (Y and Y̅). It operates at V_CC = 5 V, supports propagation delays of t_PLH/t_PHL ≤ 22 ns (typ), and delivers output drive capability of I_OH = –0.4 mA / I_OL = 8 mA. It is used in digital logic routing, address decoding, and data path selection in legacy industrial control systems.

For engineers reviewing the SN74LS151D datasheet, SN74LS151D pinout, SN74LS151D application, or SN74LS151D equivalent, key selection considerations include its 16-pin SOIC package, commercial temperature range (0°C to 70°C), TTL-compatible input thresholds, dual-output configuration, and absence of internal latching or clocking functionality.

Technical Context

The SN74LS151D implements combinational logic using standard TTL bipolar transistor architecture, with Schottky-clamped inputs and outputs to suppress saturation delay. Its truth table defines deterministic output selection based solely on A/B/C state and G̅ assertion - no internal state storage or timing dependencies exist.

All eight data inputs (I₀–I₇) are fully buffered and electrically isolated from one another; only the selected input appears at Y/Y̅. The device requires no external biasing, operates with single +5 V supply, and exhibits guaranteed noise margins of ≥0.4 V for both high and low logic levels under rated load conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Supply	+5 V nominal; operation outside 4.75–5.25 V invalidates AC/DC specs.
Propagation Delay	t_PLH/t_PHL ≤ 22 ns (max) at V_CC = 5 V, T_A = 25°C, R_L = 2 kΩ, C_L = 15 pF - sets max clock/data rate in synchronous logic paths.
Output Drive	I_OL = 8 mA (min) at V_OL ≤ 0.5 V; I_OH = –0.4 mA (min) at V_OH ≥ 2.7 V - drives up to 10 standard TTL loads directly.
Input Thresholds	V_IL ≤ 0.8 V (guaranteed low), V_IH ≥ 2.0 V (guaranteed high) - ensures interoperability with LS-TTL, ALS-TTL, and compatible logic families.
Operating Temperature	0°C to 70°C ambient - restricts use to commercial-grade environments; not qualified for extended industrial or automotive ranges.
Package	SOIC-16 (D package), 7.5 mm × 8.75 mm body, 1.27 mm pitch - surface-mount compatible with standard reflow profiles (Level-1-260°C-UNLIM).

Pinout & Package

SN74LS151D uses a 16-pin Small Outline Integrated Circuit (SOIC) package with standard D-outline dimensions per TI drawing SCBD009. Pin 1 is located at the top-left corner with notch or dot marking; leads are gull-wing, lead-free (NiPdAu), and RoHS-compliant.

Pin/Terminal	Circuit Role	Design Meaning
1 (G̅)	Active-low enable input	Y and Y̅ are high-impedance when G̅ = HIGH; device disabled regardless of A/B/C state.
2–9 (I₀–I₇)	Data inputs	Eight independent logic inputs; only one routed to Y/Y̅ based on A/B/C and G̅.
10 (Y̅)	Inverted output	Active-low complement of selected input; open-collector capable via external pull-up.
11 (Y)	True output	Active-high version of selected input; standard push-pull output stage.
12–14 (A, B, C)	Select address inputs	Binary-encoded selection: CBA = 000 → I₀, ..., 111 → I₇.
15 (GND)	Ground reference	Return path for all internal currents; must be low-impedance connection to system ground plane.
16 (V_CC)	Power supply	+5 V DC supply; requires local 0.1 µF ceramic decoupling capacitor placed within 5 mm of pin.

Key Features

Feature	Design Value
Dual complementary outputs	Simultaneous true (Y) and inverted (Y̅) outputs eliminate need for external inverters in differential routing or enable logic.
Three-bit binary select	Direct mapping of A/B/C to 8:1 data routing without address decoding logic or additional gates.
Standard TTL compatibility	Matches voltage thresholds, fan-out, and noise immunity of legacy 74LS family - enables drop-in replacement in existing designs.
Low-power Schottky (LS) process	Reduces dynamic power vs. original 74xx TTL while maintaining speed; typical I_CC = 19 mA at 5 V, 25°C.
No internal latching	Pure combinational behavior - output updates asynchronously with input changes; no clock or edge sensitivity.

Applications

Industrial Address Decoding	Legacy Test Equipment Data Routing
Use Scenario: Selecting one of eight peripheral registers in a microcontroller-based PLC backplane. IC Role / Device Role / Timing Role: Static address decoder that routes CPU address bus to target register enable lines without introducing clock skew or setup/hold constraints. Use Value: Eliminates discrete gate arrays; reduces PCB area and interconnect count while preserving deterministic propagation delay across all eight channels.	Use Scenario: Switching between eight sensor signal sources into a shared ADC channel in automated calibration hardware. IC Role / Device Role / Timing Role: Analog multiplexer front-end controller - selects analog input source based on digital control lines from test sequencer. Use Value: Provides TTL-level compatible switching with minimal crosstalk (< –50 dB typical) and no added latency in signal path timing budget.
EPROM Memory Bank Selection	Parallel Bus Arbitration Logic
Use Scenario: Enabling one of eight EPROM chips in a 64 kB memory map for vintage computing restoration projects. IC Role / Device Role / Timing Role: Chip-select generator driven by upper address bits (A13–A15); asserts CS̅ only when matching bank is addressed. Use Value: Ensures strict address decode accuracy with guaranteed setup time margin relative to memory access cycle.	Use Scenario: Resolving priority among eight interrupt request lines feeding a single CPU INTR pin. IC Role / Device Role / Timing Role: Priority encoder preprocessor - maps highest-active IRQ line to fixed vector index before CPU sampling. Use Value: Delivers deterministic, race-free priority resolution without requiring sequential polling or software overhead.

Industrial Address Decoding

Legacy Test Equipment Data Routing

Use Scenario: Selecting one of eight peripheral registers in a microcontroller-based PLC backplane.

IC Role / Device Role / Timing Role: Static address decoder that routes CPU address bus to target register enable lines without introducing clock skew or setup/hold constraints.

Use Value: Eliminates discrete gate arrays; reduces PCB area and interconnect count while preserving deterministic propagation delay across all eight channels.

Use Scenario: Switching between eight sensor signal sources into a shared ADC channel in automated calibration hardware.

IC Role / Device Role / Timing Role: Analog multiplexer front-end controller - selects analog input source based on digital control lines from test sequencer.

Use Value: Provides TTL-level compatible switching with minimal crosstalk (< –50 dB typical) and no added latency in signal path timing budget.

EPROM Memory Bank Selection

Parallel Bus Arbitration Logic

Use Scenario: Enabling one of eight EPROM chips in a 64 kB memory map for vintage computing restoration projects.

IC Role / Device Role / Timing Role: Chip-select generator driven by upper address bits (A13–A15); asserts CS̅ only when matching bank is addressed.

Use Value: Ensures strict address decode accuracy with guaranteed setup time margin relative to memory access cycle.

Use Scenario: Resolving priority among eight interrupt request lines feeding a single CPU INTR pin.

IC Role / Device Role / Timing Role: Priority encoder preprocessor - maps highest-active IRQ line to fixed vector index before CPU sampling.

Use Value: Delivers deterministic, race-free priority resolution without requiring sequential polling or software overhead.

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8:1 multiplexer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS151N	Same logic function and electrical specs; PDIP-16 through-hole package instead of SOIC-16.	Requires manual soldering or wave-solder process; unsuitable for high-density SMT production.	Choose SN74LS151N for prototyping, repair, or through-hole legacy board rework where SOIC footprint is unavailable.
SN74LS151DR	Identical SOIC-16 package and specs; differs only in tape-and-reel packaging (2500 pcs/reel) and part marking (LS151).	No functional or performance difference; same thermal, electrical, and mechanical behavior.	SN74LS151DR is the current production variant; SN74LS151D is obsolete but may remain in legacy inventory - verify availability before design-in.

Compared with SN74LS151N and SN74LS151DR, the SN74LS151D offers identical logic and timing behavior but is marked obsolete by TI; SN74LS151DR provides identical performance in modern SMT-compatible packaging with full production support and RoHS compliance.

Availability

SN74LS151D is available at Aetrix Electronics and suitable for industrial control retrofitting, legacy test equipment maintenance, and vintage computing restoration requiring stable component supply and long-term traceable sourcing.

Supply support for SN74LS151D 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 company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and consumer reach.

The SN74LS151D belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-power, pin-compatible upgrades to original 74xx TTL in commercial-grade digital systems.

FAQ

What is the function of the G̅ pin on the SN74LS151D?

The G̅ (enable) pin on the SN74LS151D is an active-low control input. When G̅ is HIGH, both Y and Y̅ outputs enter high-impedance (Hi-Z) state regardless of A/B/C or I₀–I₇ states. Only when G̅ is LOW does the SN74LS151D actively route the selected input to Y/Y̅. This allows cascading multiple SN74LS151D devices or enabling/disabling data paths in larger logic systems.

Can the SN74LS151D operate with a 3.3 V supply?

No, the SN74LS151D is specified exclusively for V_CC = 5 V ±5% operation. Its internal TTL bipolar transistors require ~5 V to meet guaranteed output drive (I_OL = 8 mA), noise margins, and propagation delay specs. Applying 3.3 V may result in marginal or non-functional behavior - use 74LVC151 or similar CMOS alternatives for 3.3 V systems.

Is the SN74LS151D pin-compatible with the SN74LS151N?

Yes, the SN74LS151D (SOIC-16) and SN74LS151N (PDIP-16) share identical pin functions and ordering of signals (G̅, I₀–I₇, Y̅, Y, A, B, C, GND, V_CC). However, their physical footprints differ: SOIC requires 1.27 mm pitch SMT pads, while PDIP uses 2.54 mm through-hole spacing. Electrical behavior is identical; only PCB layout and assembly process differ.

Does the SN74LS151D include internal pull-up or pull-down resistors on inputs?

No, the SN74LS151D has no internal pull-up or pull-down resistors on any input (G̅, A, B, C, or I₀–I₇). All inputs are TTL-compatible high-impedance nodes requiring externally defined logic levels. Floating inputs will cause unpredictable output states and increased power consumption due to input stage bias instability - always terminate unused inputs to V_CC or GND.

What is the maximum recommended clock/data toggle rate for the SN74LS151D?

The SN74LS151D is a purely combinational device with no clock input, so it does not have a "clock rate." Its usable data switching frequency depends on propagation delay (≤22 ns max) and system timing margins. For reliable operation, input transitions should settle ≥25 ns before downstream sampling edges, supporting effective data routing up to ~20 MHz in well-designed synchronous paths with adequate setup/hold guard bands.

SN74LS151D Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 16-SOIC (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Obsolete

Type:: Multiplexer

Circuit:: 1 x 8:1

Independent Circuits:: 1

Current - Output High, Low:: 400µA, 8mA

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: 0°C ~ 70°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SOIC

SN74LS151D FAQ

1.How can I place an order for SN74LS151D through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS151D 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 SN74LS151D reliable?

The price and inventory of SN74LS151D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS151D is usually 5 days.

3.What payment methods are accepted for SN74LS151D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS151D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS151D?

SN74LS151D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS151D 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 SN74LS151D?

For technical support, including SN74LS151D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS151D requirements.

6.How does Aetrix verify that SN74LS151D is sourced from the original manufacturer or authorized distributors?

All SN74LS151D 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 SN74LS151D meets industry standards.

7.What is the process for return or replacement of SN74LS151D?

All SN74LS151D units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS151D, 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 SN74LS151D part is unused and in its original packaging.

Return procedure for SN74LS151D:

1.Submit a request within 90 days.

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

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