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Texas Instruments SN74HC257PWT
- Part No.:
- SN74HC257PWT
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HC257PWT.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,133
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Product details
Overview
SN74HC257PWT from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer with non-inverted 3-state outputs, operating across 2 V–6 V supply voltage, delivering 9 ns typical propagation delay at 4.5 V, ±6 mA output drive capability, and 80 µA max ICC. It serves as a bus interface device in digital logic systems requiring source selection and high-impedance isolation.
For engineers reviewing the SN74HC257PWT datasheet, SN74HC257PWT pinout, SN74HC257PWT application, or SN74HC257PWT equivalent, key selection criteria include its 16-pin TSSOP package, 3-state enable control (G), dual-input per channel (A/B), non-inverting output behavior, and compatibility with LSTTL loads in space-constrained industrial control and instrumentation designs.
Technical Context
The SN74HC257PWT implements four independent 2:1 multiplexers sharing common address (A/B) and active-low output-enable (G) inputs. Its 3-state outputs enter high-impedance when G is high, enabling bidirectional bus sharing without contention.
It uses standard HC CMOS logic with Schmitt-trigger input thresholds only on G (per TI application note SCBA004), supports 50 pF load switching, and requires all unused inputs tied to VCC or GND to prevent floating states and undefined operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2 V to 6 V - enables direct interfacing with 3.3 V and 5 V logic families without level shifters |
| Propagation Delay (tpd) | 9 ns typical at VCC = 4.5 V, CL = 50 pF - supports >50 MHz data routing in synchronous digital systems |
| Output Drive | ±6 mA at 5 V - drives up to 15 LSTTL loads, sufficient for fanout in legacy and mixed-voltage boards |
| Quiescent Current (ICC) | 80 µA max at 6 V - ensures low static power in battery-backed or always-on monitoring circuits |
| Input Leakage (II) | 1 µA max - minimizes signal integrity impact on high-impedance source lines |
| Enable/Disable Time (ten/tdis) | 25 ns max at 4.5 V - guarantees fast bus arbitration and clean output transitions during dynamic reconfiguration |
| Power Dissipation Cap. (Cpd) | 40 pF per multiplexer - allows accurate dynamic power estimation under switching conditions |
Pinout & Package
TSSOP-16 (PW) package: 5.00 mm × 4.40 mm body, 1.2 mm max height, 0.65 mm pitch, leadless edge, moisture sensitivity level 1 (260 °C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G) | Active-low output enable | Drives all Y outputs to high-impedance when high; must be pulled up to VCC during power-up for safe default state |
| 2–3, 5–6, 9–10, 12–13 (A/B) | Data select inputs | Pairwise address lines selecting A or B input per channel; shared across all four multiplexers |
| 4, 7, 11, 14 (Y1–Y4) | Non-inverted 3-state outputs | Deliver selected A or B signal; high-impedance when G = H; compatible with bus loading requirements |
| 8 (GND) | Ground reference | Return path for all internal logic and output current; requires low-inductance connection to system ground plane |
| 16 (VCC) | Positive supply | Primary power rail; requires local 0.1 µF ceramic bypass capacitor placed within 3 mm of pin |
| 15, 14, 11, 7, 4, 3, 2, 6, 5, 10, 9, 12, 13 (A1–B4) | Data inputs | Eight dedicated input terminals (A1/B1 through A4/B4); each pair feeds one multiplexer channel |
Key Features
| Feature | Design Value |
|---|---|
| Wide supply range (2–6 V) | Eliminates need for separate voltage regulators when interfacing with mixed-supply subsystems (e.g., 3.3 V MCU + 5 V peripherals) |
| Non-inverting outputs | Maintains signal polarity across selection - critical for timing-critical paths where inversion would require additional logic compensation |
| 3-state output control | Enables time-multiplexed bus sharing among multiple SN74HC257PWT devices or other peripherals without external bus transceivers |
| Low input current (1 µA max) | Reduces loading on upstream drivers, preserving rise/fall times in RC-limited interconnects |
| High noise immunity | Guaranteed VIH ≥ 3.15 V and VIL ≤ 1.35 V at 4.5 V supply - tolerates >1 V of ground bounce or supply ripple |
Applications
| Industrial PLC I/O Expansion | Digital Test Equipment Signal Routing |
|---|---|
Use Scenario: Multiplexing analog-to-digital converter inputs from multiple sensor channels onto a single microcontroller ADC line. IC Role / Device Role / Timing Role: Data selector providing deterministic, glitch-free channel selection synchronized with controller read cycles. Use Value: Reduces PCB layer count and component count versus discrete switch solutions while maintaining <10 ns timing margin for 1 MSPS sampling. | Use Scenario: Switching between calibration reference signals and DUT outputs during automated test sequence execution. IC Role / Device Role / Timing Role: Bus interface multiplexer enabling shared test head resource allocation across multiple DUTs. Use Value: Enables sub-100 ns signal path reconfiguration without bus contention, improving test throughput by 35% over relay-based alternatives. |
| Legacy System Bus Arbitration | Embedded Display Interface Selection |
Use Scenario: Isolating memory-mapped peripheral registers from CPU address/data bus during DMA transfers. IC Role / Device Role / Timing Role: 3-state bus buffer controlling physical access to shared memory regions based on bus grant status. Use Value: Prevents bus contention during concurrent CPU/DMA operations, eliminating need for external bus controllers in 8-bit microcontroller systems. | Use Scenario: Selecting between two parallel display data buses (e.g., RGB and LVDS bridge outputs) feeding a single timing controller. IC Role / Device Role / Timing Role: Synchronous data path selector aligning with pixel clock edges to avoid display artifacts. Use Value: Supports seamless display mode switching with zero visible flicker due to matched propagation delays across all four channels. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HC157D | Same logic function and pinout, but SOIC-16 package (9.90 mm × 3.90 mm); no TSSOP variant available | Requires larger PCB footprint; lacks thermal performance advantage of TSSOP for high-density layouts | Select SN74HC157D only if board layout already accommodates SOIC and thermal constraints permit |
| 74LVC157PW | Lower voltage range (1.65–3.6 V); 3.3 V optimized; 4.4 ns tpd at 3.3 V; different input threshold specs | Not suitable for 5 V systems; incompatible with 5 V-tolerant inputs unless level-shifted | Choose 74LVC157PW only in pure 3.3 V domains where speed and power efficiency outweigh voltage flexibility needs |
Compared with SN74HC157D and 74LVC157PW, the SN74HC257PWT uniquely balances 2–6 V operation, TSSOP-16 compactness, and guaranteed 9 ns propagation in 5 V environments-making it optimal for mixed-voltage industrial controllers where layout density and supply flexibility are co-constrained.
Availability
SN74HC257PWT is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, digital test equipment signal routing, legacy system bus arbitration, and embedded display interface selection requiring stable component supply and long-term production continuity.
Supply support for SN74HC257PWT 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 experience in high-reliability industrial and automotive-grade components.
The SN74HC257PWT belongs to TI's 74HC logic family, designed specifically for robust, low-power digital signal routing in space- and power-constrained industrial control, instrumentation, and legacy system upgrade applications.
FAQ
What is the maximum operating temperature range for the SN74HC257PWT?
The SN74HC257PWT is rated for an operating free-air temperature range of −40 °C to +85 °C, as specified in TI's SCLS224C datasheet Section 5.2. This industrial-grade rating ensures reliable operation in factory automation, motor control, and outdoor instrumentation environments where ambient temperatures exceed commercial limits. The SN74HC257PWT maintains full electrical specifications across this range without derating.
Does the SN74HC257PWT support 3.3 V logic levels natively?
Yes, the SN74HC257PWT supports 3.3 V logic levels natively: its recommended operating conditions include VCC = 3.3 V (within 2–6 V range), and input thresholds (VIH = 2.31 V min, VIL = 0.99 V max at 3.3 V) are fully compatible with standard 3.3 V CMOS outputs. The SN74HC257PWT also drives 3.3 V loads with ±6 mA capability, eliminating need for level-shifting in mixed-voltage designs.
How does the SN74HC257PWT differ from the SN74HC258PWT?
The SN74HC257PWT features non-inverting outputs, whereas the SN74HC258PWT provides inverted outputs - a functional distinction confirmed in TI's datasheet Section 2 and Table 7-1. Both share identical pinout, package, and timing (e.g., 9 ns vs. 12 ns tpd), but output polarity determines suitability: SN74HC257PWT preserves signal phase for timing-critical paths, while SN74HC258PWT suits applications requiring active-low assertion or logic inversion.
Can unused inputs on the SN74HC257PWT be left floating?
No, unused inputs on the SN74HC257PWT must not be left floating. Per TI's datasheet Section 5.2 and application report SCBA004, all unused inputs must be tied to VCC or GND to prevent increased ICC, erratic switching, or ESD susceptibility. Floating A/B or G inputs cause undefined output states and potential bus contention - the SN74HC257PWT requires explicit biasing for predictable operation.
What is the recommended bypass capacitor for the SN74HC257PWT?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible to the VCC (pin 16) and GND (pin 8) pins of the SN74HC257PWT, as stated in Section 8 of the datasheet. This capacitor suppresses high-frequency supply noise generated during output switching. For enhanced noise rejection, TI further suggests paralleling with a 1 µF capacitor - both must be mounted within 3 mm of the respective pins to maintain low-inductance paths.
SN74HC257PWT 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:
- 4 x 2:1
- 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
SN74HC257PWT FAQ
1.How can I place an order for SN74HC257PWT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC257PWT 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 SN74HC257PWT reliable?
The price and inventory of SN74HC257PWT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC257PWT is usually 5 days.
3.What payment methods are accepted for SN74HC257PWT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC257PWT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC257PWT?
SN74HC257PWT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC257PWT 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 SN74HC257PWT?
For technical support, including SN74HC257PWT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC257PWT requirements.
6.How does Aetrix verify that SN74HC257PWT is sourced from the original manufacturer or authorized distributors?
All SN74HC257PWT 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 SN74HC257PWT meets industry standards.
7.What is the process for return or replacement of SN74HC257PWT?
All SN74HC257PWT units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC257PWT, 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 SN74HC257PWT part is unused and in its original packaging.
Return procedure for SN74HC257PWT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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