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STMicroelectronics 74ACT257MTR
- Part No.:
- 74ACT257MTR
- Manufacturer:
- STMicroelectronics
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
74ACT257MTR.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,682
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Product details
Overview
74ACT257MTR from STMicroelectronics is a quad 2-channel non-inverting multiplexer with 3-state outputs, designed for high-speed digital signal routing in TTL- and CMOS-compatible systems. It features 5 ns typical propagation delay at 5 V, ±24 mA symmetrical output drive, 4.5–5.5 V operating range, and active-low 3-state enable (OE). Used in data selector logic for microcontroller I/O expansion and bus arbitration.
For engineers reviewing the 74ACT257MTR datasheet, 74ACT257MTR pinout, 74ACT257MTR application, or 74ACT257MTR equivalent, key selection criteria include propagation delay matching, 50 Ω transmission line drive capability, input voltage compatibility (VIH ≥ 2.0 V, VIL ≤ 0.8 V), and guaranteed 3-state disable timing (tPZL/tPLZ ≤ 9 ns).
Technical Context
The 74ACT257 implements four independent 2:1 multiplexers sharing common SELECT and active-low OE inputs. Each channel selects between A or B inputs based on the binary state of SELECT, with non-inverting output polarity.
All inputs and outputs are ESD-protected to 2 kV, and the device uses sub-micron C2MOS technology to achieve balanced tPLH ≅ tPHL delays and symmetrical |IOH| = |IOL| = 24 mA (min) drive strength across the full –55°C to +125°C temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| tPD (typ) | 5 ns at VCC = 5 V - enables <10 ns cycle-time logic interfacing |
| VCC Range | 4.5 V to 5.5 V - supports industrial-grade 5 V rail tolerance |
| IOL / IOH (min) | 24 mA - drives 50 Ω transmission lines directly without external buffers |
| VIH / VIL | 2.0 V (min) / 0.8 V (max) - ensures reliable interfacing with TTL and older CMOS outputs |
| tPZL / tPLZ (max) | 9 ns at TA = –55°C to +125°C - guarantees fast bus release during 3-state transitions |
| ICC (max) | 4 µA at TA = 25°C - ultra-low static power for always-on control logic |
| ESD Rating | 2 kV HBM - built-in protection eliminates need for external clamps in board-level ESD zones |
Pinout & Package
74ACT257MTR is supplied in a 16-pin TSSOP package (JEDEC MO-153, 4.9 × 6.4 mm body, 0.65 mm pitch), optimized for high-density PCB layouts and automated assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | SELECT | Common control input determining A/B source selection for all four channels |
| 2,5,11,14 | 1A–4A | Data inputs from Source A; routed to outputs when SELECT = LOW |
| 3,6,10,13 | 1B–4B | Data inputs from Source B; routed to 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 when HIGH |
| 8 | GND | Digital ground reference for all internal logic and I/O structures |
| 16 | VCC | Positive supply rail (4.5–5.5 V); powers internal logic and output drivers |
Key Features
| Feature | Design Value |
|---|---|
| Quad 2:1 Multiplexer Function | Four independent data selectors sharing one SELECT and one OE - reduces component count vs discrete gates |
| 50 Ω Transmission Line Drive | Guaranteed ±24 mA drive into 50 Ω loads - eliminates need for external line drivers in backplane or ribbon cable interfaces |
| Balanced Propagation Delays | tPLH ≅ tPHL - minimizes duty-cycle distortion in clock/data routing applications |
| Wide Temperature Range | Specified from –55°C to +125°C - suitable for under-hood automotive and industrial control environments |
| Pin-Compatible Replacement | Direct drop-in for 74LS257 and 74F257 - simplifies legacy system upgrades without PCB redesign |
Applications
| Microcontroller I/O Expansion | Parallel Bus Arbitration |
|---|---|
Use Scenario: Expanding limited GPIO count on an ARM Cortex-M0 MCU to interface eight parallel sensors. IC Role / Device Role / Timing Role: Quad 2:1 mux routes sensor data selectively onto shared data bus under firmware-controlled SELECT/OE. Use Value: Enables time-multiplexed sampling without additional address decoding logic or bus transceivers. | Use Scenario: Managing access to a shared 8-bit peripheral bus among three FPGA-based subsystems. IC Role / Device Role / Timing Role: Acts as a hardware-enforced bus gate; OE controlled by priority encoder to grant exclusive access. Use Value: Prevents bus contention with sub-10 ns disable timing, eliminating arbitration glitches seen with slower logic. |
| Legacy TTL-to-CMOS Interface | Test Equipment Signal Routing |
Use Scenario: Interfacing a 74LS138 decoder output to a 5 V CMOS ADC requiring clean 0.8 V/2.0 V logic thresholds. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer; leverages VIH/VIL compatibility and 24 mA drive. Use Value: Eliminates need for discrete resistor networks or dedicated level translators while maintaining signal integrity. | Use Scenario: Automated test fixture selecting one of four calibration reference signals to DUT input. IC Role / Device Role / Timing Role: Precision signal switch; low skew and matched tPLH/tPHL ensure deterministic timing alignment. Use Value: Reduces test setup jitter below 1 ns, improving measurement repeatability for high-speed analog validation. |
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 |
|---|---|---|---|
| 74LCX257MTR | Lower VCC range (2.0–3.6 V), higher speed (tPD = 4.2 ns typ), but reduced drive (±24 mA only at 3.3 V) | Not suitable for 5 V systems; requires level translation when interfacing with TTL | Select for 3.3 V-only designs prioritizing lower power and faster switching |
| SN74ACT257DR | Identical AC/DC specs and pinout; SOIC-16 package instead of TSSOP-16 | Larger footprint and lower thermal dissipation density; less suitable for space-constrained layouts | Select when board assembly uses SOIC carriers or requires manual rework accessibility |
Compared with 74LCX257MTR and SN74ACT257DR, the 74ACT257MTR uniquely balances 5 V TTL compatibility, 50 Ω line drive, and TSSOP packaging-making it optimal for mixed-voltage industrial controllers where board area and legacy interface coexist.
Availability
74ACT257MTR is available at Aetrix Electronics and suitable for microcontroller I/O expansion, parallel bus arbitration, and legacy TTL-to-CMOS interface applications requiring stable component supply and long-term industrial availability.
Supply support for 74ACT257MTR 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, Switzerland, specializing in automotive, industrial, and power management ICs with vertical manufacturing capabilities.
The 74ACT high-speed CMOS logic family was developed to replace bipolar TTL in noise-sensitive, power-constrained systems while maintaining full pin and functional compatibility with legacy 74-series devices.
FAQ
What is the maximum recommended operating temperature for 74ACT257MTR?
The 74ACT257MTR is fully specified from –55°C to +125°C ambient temperature. Its DC and AC parameters-including propagation delay, output drive, and leakage current-are guaranteed across this full industrial and extended automotive range, making it suitable for under-hood and factory-floor deployments without derating.
Can 74ACT257MTR drive a 50 Ω coaxial cable directly?
Yes. The device guarantees ±24 mA output drive into 50 Ω loads at VCC = 5 V, meeting incident-wave switching requirements for transmission lines with characteristic impedances as low as 50 Ω. No series termination resistor is required when driving such lines at frequencies up to 100 MHz.
Is the 74ACT257MTR functionally identical to the 74LS257?
Yes-pinout, truth table, and logic function are identical. However, 74ACT257MTR offers superior performance: 5 ns vs. 15 ns typical propagation delay, 24 mA vs. 8 mA output drive, and 2 kV ESD protection not present in 74LS257. It operates at the same 5 V supply but draws significantly less quiescent current.
What happens to the outputs when OE is left unconnected?
OE is an active-low input with no internal pull-up. If left floating, it may assume an indeterminate logic state due to noise coupling, causing unpredictable output behavior-including partial enabling or oscillation. STMicroelectronics recommends tying OE to VCC via a 10 kΩ resistor if permanently enabled, or to a controlled logic signal in all production designs.
74ACT257MTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- 74ACT
- Package/Case:
- 16-SOIC (0.154", 3.90mm 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
74ACT257MTR FAQ
1.How can I place an order for 74ACT257MTR through Aetrix?
Please submit a Request for Quotation (RFQ) for 74ACT257MTR 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 74ACT257MTR reliable?
The price and inventory of 74ACT257MTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74ACT257MTR is usually 5 days.
3.What payment methods are accepted for 74ACT257MTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74ACT257MTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74ACT257MTR?
74ACT257MTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74ACT257MTR 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 74ACT257MTR?
For technical support, including 74ACT257MTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74ACT257MTR requirements.
6.How does Aetrix verify that 74ACT257MTR is sourced from the original manufacturer or authorized distributors?
All 74ACT257MTR 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 74ACT257MTR meets industry standards.
7.What is the process for return or replacement of 74ACT257MTR?
All 74ACT257MTR units undergo pre-shipment inspection (PSI). If there is an issue with 74ACT257MTR, 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 74ACT257MTR part is unused and in its original packaging.
Return procedure for 74ACT257MTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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