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

Texas Instruments SN74HC251PWT

Name: SN74HC251PWT
Brand: Texas Instruments
SKU: SN74HC251PWT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74HC251PWT

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-TSSOP (0.173", 4.40mm Width)

Datasheet:: SN74HC251PWT.pdf

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

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Product details

Overview

SN74HC251PWT from Texas Instruments is an 8-to-1 data selector/multiplexer with complementary 3-state outputs, full binary decoding, and strobe-controlled enable logic. It operates from 2 V to 6 V, delivers ±6 mA output drive at 5 V, exhibits typical propagation delay of 9 ns (CL = 50 pF), and supports parallel-to-serial conversion in bus-interfaced digital systems.

For engineers reviewing the SN74HC251PWT datasheet, SN74HC251PWT pinout, SN74HC251PWT application, or SN74HC251PWT equivalent, this page provides verified functional mode behavior, validated switching characteristics under 50 pF and 150 pF loads, confirmed thermal resistance (R_θJA = 108 °C/W), and precise TSSOP-16 package mapping for layout and thermal design.

Technical Context

The SN74HC251PWT implements full 3-bit binary decoding (A/B/C inputs) to select one of eight data inputs (D0–D7), routing it to complementary true (Y) and inverted (W) 3-state outputs controlled by OE. Its high-impedance outputs allow direct connection to shared data buses without contention.

It features dual-output architecture with simultaneous Y and W assertion, enabling both logic polarities on a single device. The device meets HC-series CMOS performance: low input current (≤1 μA), low quiescent ICC (≤80 μA), and robust noise immunity across its 2–6 V operating range.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage Range	2 V to 6 V - supports mixed-voltage system interfacing and battery-powered operation down to 2 V.
Propagation Delay (t_pd)	19 ns (typ) at V_CC = 6 V, CL = 50 pF - enables reliable timing in 50-MHz-class synchronous logic paths.
Output Drive Strength	±6 mA at V_CC = 5 V - sufficient to directly drive 15 LSTTL loads or terminate short PCB traces without buffers.
Quiescent Supply Current (I_CC)	80 μA max - ensures ultra-low static power in always-on control logic or sleep-mode subsystems.
Input Leakage Current	1 μA max - prevents unintended logic transitions when inputs are tied to high-impedance sources or pull-ups.
3-State Enable/Disable Time (t_en/t_dis)	9 ns (typ) at V_CC = 6 V - guarantees fast bus arbitration and glitch-free output transitions during multiplexing.

Pinout & Package

TSSOP-16 package (PW), 5.00 mm × 4.40 mm body size, 1.2 mm max height, 0.65 mm lead pitch, RoHS-compliant NiPdAu/Sn lead finish, MSL Level-1 (260 °C peak reflow).

Pin/Terminal	Circuit Role	Design Meaning
1 (OE)	Output Enable (active-low)	Strobe control: pulls Y/W to high-Z when high; enables outputs when low - critical for bus arbitration timing.
2–4 (C, B, A)	Binary Select Inputs	3-bit address lines determining which D-input (D0–D7) routes to Y/W - decoded internally with no external logic required.
5–12 (D0–D7)	Data Inputs	Eight independent logic inputs; only one selected by CBA passes through - supports flexible source routing in state machines or ADC muxing.
13 (W)	Inverted Output	Complementary active-low version of selected data - eliminates need for external inverters in differential signaling or enable logic.
14 (Y)	True Output	Active-high version of selected data - drives positive-logic loads directly without inversion overhead.
15 (GND)	Ground Reference	Primary return path for all I/O and supply currents - must be low-inductance and adjacent to bypass capacitor.
16 (V_CC)	Power Supply	CMOS rail (2–6 V); requires local 0.1-μF ceramic bypass capacitor per TI layout guidelines to suppress switching noise.

Key Features

Feature	Design Value
Complementary 3-state outputs (Y/W)	Eliminates need for external inverters and separate bus drivers - reduces component count and board area in data-path designs.
Strobe-controlled output enable (OE)	Enables precise timing control over bus access - allows synchronized data capture across multiple devices using common OE signals.
Full internal binary decoding	Removes requirement for external address decoders - simplifies control logic in microcontroller GPIO expansion or FPGA glue logic.
Parallel-to-serial conversion capability	Supports time-division multiplexing of sensor arrays or status registers - e.g., reading eight analog sensors via single ADC channel.
Wide 2–6 V supply range	Permits interoperability between 3.3 V microcontrollers and 5 V legacy peripherals - avoids level-shifter components in mixed-voltage systems.

Applications

Industrial Control Logic	Digital Test Equipment
Use Scenario: Routing discrete sensor status bits (e.g., limit switches, fault flags) to a central PLC input port. IC Role / Device Role / Timing Role: Data selector consolidating eight asynchronous inputs into one time-multiplexed stream synchronized to PLC scan cycle. Use Value: Reduces I/O pin count on controller by 7× while maintaining deterministic sampling order and avoiding bus contention via 3-state isolation.	Use Scenario: Switching between multiple calibration reference voltages during automated test sequence execution. IC Role / Device Role / Timing Role: Precision signal path selector enabling rapid, glitch-free voltage source changes under microprocessor control. Use Value: Achieves sub-10 ns output transition stability (per t_pd spec), ensuring accurate settling before ADC sampling in <100 ns test cycles.
Embedded System Bus Interface	Programmable Logic Expansion
Use Scenario: Sharing a single UART TX line among multiple peripheral modules (e.g., GPS, BLE, debug console) in resource-constrained MCU designs. IC Role / Device Role / Timing Role: Bidirectional bus multiplexer managing output contention using OE-strobed 3-state control. Use Value: Enables software-selectable communication path without hardware redesign - leverages ±6 mA drive to meet UART driver load requirements directly.	Use Scenario: Extending limited FPGA I/O pins to drive 8-bit LED indicators or 7-segment displays using time-multiplexed scanning. IC Role / Device Role / Timing Role: High-speed data selector generating dynamic digit enable signals synchronized to display refresh clock. Use Value: Delivers 9 ns typical propagation delay - ensures minimal skew between digit selection and segment update, preventing visible flicker at >200 Hz scan rates.

Industrial Control Logic

Digital Test Equipment

Use Scenario: Routing discrete sensor status bits (e.g., limit switches, fault flags) to a central PLC input port.

IC Role / Device Role / Timing Role: Data selector consolidating eight asynchronous inputs into one time-multiplexed stream synchronized to PLC scan cycle.

Use Value: Reduces I/O pin count on controller by 7× while maintaining deterministic sampling order and avoiding bus contention via 3-state isolation.

Use Scenario: Switching between multiple calibration reference voltages during automated test sequence execution.

IC Role / Device Role / Timing Role: Precision signal path selector enabling rapid, glitch-free voltage source changes under microprocessor control.

Use Value: Achieves sub-10 ns output transition stability (per t_pd spec), ensuring accurate settling before ADC sampling in <100 ns test cycles.

Embedded System Bus Interface

Programmable Logic Expansion

Use Scenario: Sharing a single UART TX line among multiple peripheral modules (e.g., GPS, BLE, debug console) in resource-constrained MCU designs.

IC Role / Device Role / Timing Role: Bidirectional bus multiplexer managing output contention using OE-strobed 3-state control.

Use Value: Enables software-selectable communication path without hardware redesign - leverages ±6 mA drive to meet UART driver load requirements directly.

Use Scenario: Extending limited FPGA I/O pins to drive 8-bit LED indicators or 7-segment displays using time-multiplexed scanning.

IC Role / Device Role / Timing Role: High-speed data selector generating dynamic digit enable signals synchronized to display refresh clock.

Use Value: Delivers 9 ns typical propagation delay - ensures minimal skew between digit selection and segment update, preventing visible flicker at >200 Hz scan rates.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74HC151PWR	Identical logic function and pinout; same TSSOP-16 package; differs only in output configuration (single-ended Y only, no complementary W output).	Lacks inverted output - requires external inverter if both polarities needed; suitable where space or cost constraints eliminate need for W.	Select SN74HC151PWR when only true output is required and board layout must minimize component count.
74LVC151PW,118	Lower V_CC range (1.65–3.6 V); higher speed (t_pd = 5.1 ns typ at 3.3 V); different pinout (no W output; OE active-high).	Not compatible with 5 V systems; requires level translation if interfacing with 5 V logic; optimized for modern low-voltage SoC interfaces.	Choose 74LVC151PW,118 for 3.3 V-only designs demanding maximum speed and lowest power, accepting pinout and polarity changes.

Compared with SN74HC151PWR, SN74HC251PWT adds complementary output capability without increasing pin count or package size; versus 74LVC151PW,118, it trades speed and voltage range for broader legacy-system compatibility and dual-polarity signal generation.

Availability

SN74HC251PWT is available at Aetrix Electronics and suitable for industrial control logic, digital test equipment, embedded system bus interface, and programmable logic expansion requiring stable component supply and long-term manufacturability.

Supply support for SN74HC251PWT 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 ICs, with decades of expertise in high-reliability, industry-standard logic families.

The SN74HC251PWT belongs to TI's 74HC high-speed CMOS logic product line, designed for robust, low-power digital signal routing in industrial, automotive, and communications systems where wide supply range and bus compatibility are essential.

FAQ

What is the maximum operating temperature for SN74HC251PWT?

The SN74HC251PWT is rated for operation from −40 °C to +85 °C ambient temperature, as specified in TI's recommended operating conditions. This range aligns with commercial-grade applications and is validated across all electrical parameters in the datasheet's switching and DC characteristics tables.

Does SN74HC251PWT require external pull-up resistors on its inputs?

No, SN74HC251PWT does not require external pull-up resistors on its inputs. All inputs (A, B, C, D0–D7, OE) have defined logic thresholds and low leakage (≤1 μA), so they may be driven directly by CMOS or TTL sources. Unused inputs must be tied to V_CC or GND per TI's SCBA004 guidance to prevent floating states.

Can SN74HC251PWT drive a 50-pF capacitive load reliably at 6 V supply?

Yes, SN74HC251PWT is characterized for CL = 50 pF in its switching specifications: typical t_pd is 19 ns and t_en/t_dis is 9 ns at V_CC = 6 V. These values confirm stable, specification-compliant operation driving 50-pF loads such as PCB traces or input capacitance of downstream logic gates.

Is there a drop-in replacement for SN74HC251PWT with identical pinout and function?

No verified drop-in replacement exists for SN74HC251PWT with identical pinout, complementary outputs, and 3-state enable behavior. SN74HC151PWR shares the same TSSOP-16 footprint and select logic but lacks the W (inverted) output. Any substitution requires circuit-level validation of output polarity and bus timing.

What is the thermal resistance (R_θJA) of SN74HC251PWT in its TSSOP package?

The junction-to-ambient thermal resistance (R_θJA) for SN74HC251PWT in the TSSOP-16 (PW) package is 108 °C/W, as published in TI's SCLS132F datasheet Section 5.3. This value assumes standard JEDEC 2-layer board conditions and informs thermal design for continuous operation near maximum power dissipation.

SN74HC251PWT Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74HC

Package/Case:: 16-TSSOP (0.173", 4.40mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Multiplexer

Circuit:: 1 x 8:1

Independent Circuits:: 1

Current - Output High, Low:: 7.8mA, 7.8mA

Voltage Supply Source:: Single Supply

Voltage - Supply:: 2V ~ 6V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-TSSOP

SN74HC251PWT FAQ

1.How can I place an order for SN74HC251PWT through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74HC251PWT 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 SN74HC251PWT reliable?

The price and inventory of SN74HC251PWT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC251PWT is usually 5 days.

3.What payment methods are accepted for SN74HC251PWT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC251PWT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74HC251PWT?

SN74HC251PWT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74HC251PWT 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 SN74HC251PWT?

For technical support, including SN74HC251PWT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC251PWT requirements.

6.How does Aetrix verify that SN74HC251PWT is sourced from the original manufacturer or authorized distributors?

All SN74HC251PWT 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 SN74HC251PWT meets industry standards.

7.What is the process for return or replacement of SN74HC251PWT?

All SN74HC251PWT units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC251PWT, 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 SN74HC251PWT part is unused and in its original packaging.

Return procedure for SN74HC251PWT:

1.Submit a request within 90 days.

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

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