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Texas Instruments CD74HCT257MT
- Part No.:
- CD74HCT257MT
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CD74HCT257MT.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,076
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Product details
Overview
CD74HCT257MT from Texas Instruments is a quad 2-input multiplexer with three-state non-inverting outputs, designed for data routing in digital logic systems. It features 4.5V–5.5V operation, 12ns typical propagation delay (CL = 15pF), and operates across –55°C to +125°C. Its active-low Output Enable (OE) allows bus sharing in microcontroller peripheral interfaces and industrial control backplanes.
For engineers reviewing the CD74HCT257MT datasheet, CD74HCT257MT pinout, CD74HCT257MT application, or CD74HCT257MT equivalent, key selection criteria include LSTTL-compatible input thresholds (VIL ≤ 0.8V, VIH ≥ 2.0V), SOIC-16 package compatibility, three-state output drive capability, and wide-temperature reliability for aerospace and automotive subsystems.
Technical Context
The CD74HCT257MT implements four independent 2:1 multiplexers sharing one common Select (S) input and one active-low Output Enable (OE) control line. Each multiplexer routes either I0 or I1 to its Y output based on S, while OE places all Y outputs in high-impedance state when asserted high.
Its HCT logic family ensures direct compatibility with LSTTL inputs while delivering CMOS-level quiescent current (ICC ≤ 160µA over full temperature range) and noise immunity (NIL/NIH = 30% of VCC at 5V). Propagation delays are characterized for both data (I→Y) and control (S→Y, OE→Y) paths under defined load conditions (CL = 15pF/50pF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HCT - enables direct interface with legacy LSTTL outputs without level shifters |
| Supply Voltage Range | 4.5V to 5.5V - ensures stable operation within standard 5V ±5% rail tolerances |
| Propagation Delay (I→Y) | 13ns typical at 5V, CL = 15pF - supports >30MHz data switching in synchronous logic |
| Input Thresholds | VIL ≤ 0.8V (max), VIH ≥ 2.0V (min) - guarantees reliable recognition of TTL logic levels |
| Operating Temperature | –55°C to +125°C - qualified for extended-range industrial, military, and automotive environments |
| Output Drive | Three-state non-inverting - enables bidirectional bus arbitration and avoids contention on shared data lines |
| Input Leakage Current | ±1µA max at full temperature range - minimizes loading on upstream drivers and preserves signal integrity |
Pinout & Package
CD74HCT257MT is housed in a 16-lead SOIC (Small Outline Integrated Circuit) package with 1.27mm lead pitch, JEDEC MS-012 compliant, and RoHS-compliant NiPdAu lead finish. The package supports surface-mount reflow per Level-1-260°C rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4, 5, 12, 13, 15, 16 | Data Inputs (1I0, 1I1, 2I0, 2I1, 3I0, 3I1, 4I0, 4I1) | Eight independent logic inputs grouped as four pairs; each pair feeds one multiplexer channel |
| 3 | Select Input (S) | Common control determining which input (I0 or I1) passes to all four Y outputs |
| 6 | Ground (GND) | Reference return path for all internal logic and output drivers |
| 7, 8, 10, 11 | Outputs (1Y, 2Y, 3Y, 4Y) | Four buffered, three-state, non-inverting outputs - high-impedance when OE = HIGH |
| 9 | Output Enable (OE) | Active-low global enable; forces all Y outputs into high-Z regardless of S or data inputs |
| 14 | Supply (VCC) | Positive power supply terminal; must be decoupled locally to suppress switching noise |
Key Features
| Feature | Design Value |
|---|---|
| LSTTL-Compatible Inputs | Meets VIH ≥ 2.0V / VIL ≤ 0.8V specs - eliminates need for external level translation when interfacing with 74LS-series devices |
| Three-State Outputs | Enables time-multiplexed bus sharing across multiple CD74HCT257MT devices or other peripherals without external bus buffers |
| Balanced Propagation Delays | tPLH ≈ tPHL across all channels - reduces skew in parallel data paths critical for synchronous register-to-bus transfers |
| Low Quiescent Current | ICC ≤ 160µA over –55°C to +125°C - supports low-power operation in always-on industrial monitoring nodes |
| High Noise Immunity | NIL/NIH = 30% of VCC at 5V - maintains logic integrity in electrically noisy motor-control or power-conversion environments |
Applications
| Industrial PLC I/O Expansion | Aerospace Avionics Data Routing |
|---|---|
Use Scenario: Multiplexing discrete sensor inputs (limit switches, pressure transducers) onto a shared microcontroller ADC or GPIO bus. IC Role / Device Role / Timing Role: Quad 2:1 selector consolidates eight field signals into four routed lanes, synchronized by system clock and controlled via FPGA-configured OE/S. Use Value: Reduces PCB trace count and connector pins by 50% versus individual signal routing, while maintaining deterministic timing via matched propagation delays. |
Use Scenario: Selecting between primary and backup flight control data streams in redundant avionics modules. IC Role / Device Role / Timing Role: Four-channel data switch provides failover path selection under supervision of health-monitoring logic; OE enables safe isolation during fault conditions. Use Value: Enables hot-swappable redundancy architecture with sub-15ns switching latency and guaranteed operation at –55°C during high-altitude cold-soak. |
| Automotive Body Control Module | Test Equipment Signal Conditioning |
Use Scenario: Routing door lock actuator commands and window motor feedback signals through a single CAN-connected MCU port. IC Role / Device Role / Timing Role: CD74HCT257MT acts as a configurable signal router between LIN transceivers and MCU GPIOs, with OE coordinated by watchdog timer. Use Value: Supports ASIL-B functional safety requirements via predictable three-state behavior during reset and brown-out events. |
Use Scenario: Switching calibration reference voltages or test stimulus sources into precision analog front-ends during automated bench testing. IC Role / Device Role / Timing Role: Logic-controlled multiplexer selects among four calibrated voltage standards before feeding 24-bit delta-sigma ADCs. Use Value: Achieves <1 LSB gain error contribution due to low input leakage (±1µA) and minimal channel-to-channel crosstalk (<–50dB). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad 2-input multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT257N | Same HCT logic, identical pinout, PDIP-16 package only - no SOIC variant available | Requires through-hole assembly; unsuitable for space-constrained SMT designs | Select SN74HCT257N only for legacy through-hole prototyping or repair where SOIC footprint is unavailable |
| 74LVX257M | Lower-voltage LVX family (2.7V–3.6V); VIH/VIL thresholds incompatible with 5V LSTTL | Designed for 3.3V mixed-signal systems - cannot directly replace CD74HCT257MT in 5V environments | Choose 74LVX257M only when migrating to 3.3V logic domains and redesigning supply architecture |
Compared with SN74HCT257N and 74LVX257M, CD74HCT257MT uniquely combines LSTTL input compatibility, SOIC-16 surface-mount packaging, and extended temperature qualification - making it the only drop-in solution for high-reliability 5V industrial control upgrades requiring zero PCB revision.
Availability
CD74HCT257MT is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, aerospace avionics data routing, and automotive body control module designs requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HCT257MT 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 solutions, with decades of heritage in high-reliability logic families.
The CD74HCT257MT belongs to TI's CD74HCT high-speed CMOS logic series, engineered for robust 5V system integration where LSTTL compatibility, wide temperature operation, and three-state bus control are essential.
FAQ
What is the maximum operating frequency supported by CD74HCT257MT?
The CD74HCT257MT does not specify a maximum clock frequency in its datasheet, as it is a combinational logic device without internal clocking. However, with a typical propagation delay of 13ns (I→Y) at 5V and CL = 15pF, it supports reliable data switching up to approximately 30MHz in synchronous systems where setup/hold timing margins are maintained. System-level frequency limits depend on board layout, load capacitance, and driver strength.
Does CD74HCT257MT support 3.3V logic inputs?
No, CD74HCT257MT is an HCT-family device optimized for 4.5V–5.5V operation and requires LSTTL-compatible input thresholds: VIH ≥ 2.0V (minimum) and VIL ≤ 0.8V (maximum). Applying 3.3V logic signals may result in marginal or unreliable switching, especially over temperature. For 3.3V systems, consider TI's 74LVC257 or similar LVCMOS-compatible alternatives instead of CD74HCT257MT.
Can CD74HCT257MT outputs drive standard LSTTL loads directly?
Yes, CD74HCT257MT outputs are rated to drive up to 10 LSTTL loads over the full temperature range (–55°C to +125°C), as confirmed in the "Fanout" specification. This capability is enabled by its buffered outputs and output drive strength meeting LSTTL VOH/VOL and sink/source current requirements (IO = ±25mA per pin), making CD74HCT257MT suitable for direct interconnection with legacy 74LS-series logic without additional buffers.
Is CD74HCT257MT pin-compatible with CD74HC257MT?
Yes, CD74HCT257MT and CD74HC257MT share identical pinouts, package dimensions (SOIC-16), and functional block diagrams. The key difference lies in input threshold compatibility: CD74HCT257MT accepts LSTTL inputs (VIH ≥ 2.0V), while CD74HC257MT requires CMOS-level inputs (VIH ≥ 3.15V at 4.5V). Swapping them requires verifying upstream driver logic levels - CD74HCT257MT is not a drop-in replacement if driven by HC-series outputs.
What is the purpose of the Output Enable (OE) pin on CD74HCT257MT?
The OE pin on CD74HCT257MT is an active-low control that places all four Y outputs (1Y–4Y) into high-impedance state regardless of the Select (S) input or data inputs. This enables bus-sharing functionality - multiple CD74HCT257MT devices can coexist on the same data lines, with only one enabled at a time. When OE is HIGH, outputs float; when LOW, normal multiplexing resumes. This feature is essential for constructing scalable data routing architectures without contention.
CD74HCT257MT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 6mA, 6mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
CD74HCT257MT FAQ
1.How can I place an order for CD74HCT257MT through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT257MT 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 CD74HCT257MT reliable?
The price and inventory of CD74HCT257MT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT257MT is usually 5 days.
3.What payment methods are accepted for CD74HCT257MT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT257MT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT257MT?
CD74HCT257MT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT257MT 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 CD74HCT257MT?
For technical support, including CD74HCT257MT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT257MT requirements.
6.How does Aetrix verify that CD74HCT257MT is sourced from the original manufacturer or authorized distributors?
All CD74HCT257MT 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 CD74HCT257MT meets industry standards.
7.What is the process for return or replacement of CD74HCT257MT?
All CD74HCT257MT units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT257MT, 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 CD74HCT257MT part is unused and in its original packaging.
Return procedure for CD74HCT257MT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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