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STMicroelectronics 74AC257TTR
- Part No.:
- 74AC257TTR
- Manufacturer:
- STMicroelectronics
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
74AC257TTR.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,373
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Product details
Overview
74AC257TTR from STMicroelectronics is a quad 2-channel non-inverting multiplexer with 3-state outputs, designed for high-speed data routing in digital logic systems. It operates from 2V to 6V, delivers 4.5ns typical propagation delay at 5V, supports ±24mA symmetrical output drive, and features active-low 3-state enable (OE) and common SELECT control. Used in address/data bus multiplexing and signal path selection in industrial controllers.
For engineers reviewing the 74AC257TTR datasheet, 74AC257TTR pinout, 74AC257TTR application, or 74AC257TTR equivalent, key selection criteria include its 50Ω transmission line driving capability, balanced tPLH/tPHL delays, latch-up immunity, ESD protection (2kV), and TSSOP-16 package compatibility with space-constrained PCB layouts.
Technical Context
The device implements four independent 2:1 multiplexers sharing one SELECT and one active-low OE input, enabling simultaneous channel selection and output tri-state control. All inputs are CMOS-compatible with 28% VCC noise margins, and outputs exhibit symmetrical |IOH| = |IOL| ≥ 24mA drive strength under 5.5V supply.
It uses sub-micron C2MOS technology for low ICC (4µA max at 25°C) and improved latch-up immunity. Propagation delays are specified down to 2V operation, with guaranteed performance on 50Ω transmission lines and input rise/fall time compliance of 8 ns/V across 3.0–5.5V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2V to 6V - Supports mixed-voltage system interfacing and battery-backed logic rails. |
| tPD (Typ.) | 4.5ns at VCC = 5V - Enables >100MHz data switching in synchronous bus architectures. |
| IOL / IOH | ≥24mA - Drives 50Ω transmission lines directly without external buffers. |
| VNIH / VNIL | 28% VCC min - Provides robust noise rejection in electrically noisy industrial environments. |
| ICC (Max) | 4µA at TA = 25°C - Enables ultra-low static power in always-on control logic sections. |
| ESD Rating | 2kV HBM - Protects against handling-induced discharge during assembly and field service. |
| Operating Temp | −55°C to +125°C - Qualified for extended-temperature industrial and automotive under-hood applications. |
Pinout & Package
TSSOP-16 package: 4.9mm × 6.4mm body, 0.65mm pitch, 1.1mm height, lead-free and RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | SELECT | Common control input selecting A (LOW) or B (HIGH) source per channel. |
| 2,5,11,14 | 1A–4A | Data inputs from Source A; routed to corresponding Y outputs when SELECT = LOW. |
| 3,6,10,13 | 1B–4B | Data inputs from Source B; routed to corresponding Y outputs when SELECT = HIGH. |
| 4,7,9,12 | 1Y–4Y | Non-inverting multiplexed outputs; enter high-impedance state when OE = HIGH. |
| 15 | OE | Active-low 3-state enable; disables all outputs simultaneously for bus sharing. |
| 8 | GND | Digital ground reference for logic thresholds and current return path. |
| 16 | VCC | Positive supply rail; powers internal logic and output drivers across full 2–6V range. |
Key Features
| Feature | Design Value |
|---|---|
| Quad 2:1 Multiplexing | Four independent channels share one SELECT and OE, reducing control signal count and PCB routing complexity. |
| 3-State Output Control | Single active-low OE pin enables bus arbitration and prevents contention in shared-data-path systems. |
| 50Ω Line Driving | Guaranteed output drive into 50Ω loads eliminates need for external termination resistors in high-speed interconnects. |
| Low-Power CMOS | 4µA max quiescent current allows integration into power-sensitive portable and remote-sensor electronics. |
| Extended Temperature Range | −55°C to +125°C operation supports deployment in harsh environments including motor drives and power converters. |
Applications
| Industrial PLC I/O Modules | Automotive Body Control Units |
|---|---|
Use Scenario: Routing sensor inputs (e.g., temperature, pressure) to ADCs while isolating unused channels. IC Role / Device Role / Timing Role: Signal selector enabling dynamic reconfiguration of analog front-end paths without FPGA overhead. Use Value: Reduces component count vs. discrete switches; maintains <4.5ns timing integrity across multiple sensor sampling cycles. | Use Scenario: Multiplexing switch status (door lock, window lift, mirror position) onto shared CAN/LIN interface lines. IC Role / Device Role / Timing Role: Digital signal router consolidating mechanical input signals before protocol encoding. Use Value: Eliminates need for additional microcontroller GPIOs; leverages 2kV ESD protection for direct connection to vehicle harnesses. |
| Test Equipment Signal Switching | Legacy System Bus Interface Adapters |
Use Scenario: Selecting between calibration references and DUT signals in automated test fixtures. IC Role / Device Role / Timing Role: Precision signal path selector with matched tPLH/tPHL ensuring deterministic switching latency. Use Value: Enables sub-5ns timing correlation between stimulus and measurement paths in high-resolution ATE. | Use Scenario: Bridging 3.3V microcontrollers to 5V legacy peripherals (e.g., EPROMs, DACs) via level-flexible data routing. IC Role / Device Role / Timing Role: Voltage-tolerant bus multiplexer supporting dual-rail operation without level shifters. Use Value: Simplifies migration from older 5V designs by maintaining pin- and function-compatibility with 74-series logic families. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AC257PWR | TSSOP-16, same AC/DC specs; TI's version has slightly higher ICC (8µA typ) and lower ESD rating (1.5kV). | Valid for commercial-temp designs but not qualified for −55°C operation. | Prefer for cost-sensitive consumer-grade boards where extended temp is unnecessary. |
| 74VHC257MTCX | Same pinout; VHC family offers lower ICC (2µA) but reduced drive (±8mA) and no 50Ω line-driving guarantee. | Suitable only for short-board traces; requires external buffers for transmission-line loads. | Select when ultra-low static power dominates over signal integrity requirements. |
Compared with SN74AC257PWR and 74VHC257MTCX, the 74AC257TTR uniquely combines −55°C qualification, 24mA drive, and 50Ω line-driving assurance-making it optimal for industrial and automotive signal routing where timing, noise immunity, and environmental ruggedness are co-critical.
Availability
74AC257TTR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, test equipment signal switching, and legacy system bus interface adapters requiring stable component supply across extended temperature ranges.
Supply support for 74AC257TTR 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in automotive, industrial, and power management ICs with strong analog and mixed-signal design heritage.
The 74AC logic family targets high-speed, low-power digital interfacing in industrial automation and automotive electronics, emphasizing robustness, wide supply range, and compatibility with legacy TTL/CMOS systems.
FAQ
What is the maximum clock frequency supported by the 74AC257TTR?
The device does not operate on a clock; it is combinational logic. Its usable data rate depends on propagation delay and load. With 4.5ns typical tPD and 50pF load, it reliably handles data transitions up to ~100MHz in point-to-point routing, assuming proper signal integrity practices like controlled impedance and termination.
Can the 74AC257TTR be used with 3.3V-only systems?
Yes. The 74AC257TTR is fully specified from 2V to 6V, including 3.3V operation. At VCC = 3.3V, VIH is 2.1V (min), VIL is 1.5V (max), VOH is ≥2.9V at -50µA, and VOL is ≤0.1V at 50µA-ensuring clean interfacing with standard 3.3V CMOS logic families.
Is the 74AC257TTR pin-compatible with older 74LS257 devices?
No. While functionally identical and pin-for-pin compatible with 74HC257 and 74HCT257, the 74AC257TTR is not compatible with bipolar 74LS257 due to different input thresholds, output drive strength, and power supply requirements-LS devices require 5V only and draw significantly more current.
Does the 74AC257TTR require external pull-up or pull-down resistors on SELECT or OE?
No. Internal input circuitry ensures defined logic states without external biasing. However, in floating-input scenarios (e.g., unconnected OE), a 10kΩ pull-down resistor is recommended to guarantee reliable high-impedance output behavior and prevent unintended channel activation during power-up or reset sequences.
74AC257TTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- 74AC
- 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:
- 24mA, 24mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
74AC257TTR FAQ
1.How can I place an order for 74AC257TTR through Aetrix?
Please submit a Request for Quotation (RFQ) for 74AC257TTR 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 74AC257TTR reliable?
The price and inventory of 74AC257TTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC257TTR is usually 5 days.
3.What payment methods are accepted for 74AC257TTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC257TTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74AC257TTR?
74AC257TTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74AC257TTR 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 74AC257TTR?
For technical support, including 74AC257TTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC257TTR requirements.
6.How does Aetrix verify that 74AC257TTR is sourced from the original manufacturer or authorized distributors?
All 74AC257TTR 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 74AC257TTR meets industry standards.
7.What is the process for return or replacement of 74AC257TTR?
All 74AC257TTR units undergo pre-shipment inspection (PSI). If there is an issue with 74AC257TTR, 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 74AC257TTR part is unused and in its original packaging.
Return procedure for 74AC257TTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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