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STMicroelectronics 74AC244MTR
- Part No.:
- 74AC244MTR
- Manufacturer:
- STMicroelectronics
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
74AC244MTR.pdf
- Description:
- IC BUFF NON-INVERT 6V 20SOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,482
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Product details
Overview
74AC244MTR from STMicroelectronics is an advanced high-speed CMOS octal bus buffer with non-inverting 3-state outputs, designed for memory address/data bus driving and system-level signal isolation. It features 3.8 ns typical propagation delay at 5V, ±24 mA output drive, 2V–6V operating voltage range, and pin/function compatibility with standard 74-series 244 devices. Used in industrial control backplanes and legacy embedded bus interfaces.
For engineers reviewing the 74AC244MTR datasheet, 74AC244MTR pinout, 74AC244MTR application, or 74AC244MTR equivalent, key selection criteria include 3-state enable timing (tPZL/tPHZ ≤ 10.5 ns), symmetrical output impedance, 50 Ω transmission line drive capability, ESD immunity (2 kV HBM), and wide VCC tolerance (2–6 V) for mixed-voltage system integration.
Technical Context
The 74AC244MTR implements two independent 4-bit non-inverting buffer groups, each controlled by a dedicated 3-state output enable input (1G and 2G). Its sub-micron C2MOS process enables low ICC (4 µA max at 25°C) while maintaining rail-to-rail output swing and balanced tPLH/tPHL propagation delays.
Input thresholds are specified as 28% VCC minimum noise immunity (VNIH/VNIL), supporting robust operation in noisy industrial environments. All I/O pins include integrated protection diodes, delivering 2 kV HBM ESD immunity without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay (tPD) | 3.8 ns typ. at VCC = 5V - enables <260 MHz bus toggle rates in point-to-point configurations |
| Output Drive (IOH/IOL) | ±24 mA min. - drives 50 Ω transmission lines directly without termination resistors |
| Supply Voltage Range | 2 V to 6 V - supports interoperability across 3.3 V and 5 V logic domains |
| Quiescent Current (ICC) | 4 µA max. at TA = 25°C - suitable for low-power standby modes in battery-backed systems |
| Noise Immunity (VNIH/VNIL) | 28 % VCC min. - rejects >1.4 V peak noise on 5 V buses without false switching |
| ESD Protection | 2 kV HBM - eliminates need for external TVS on board-level I/O traces |
| Operating Temperature | –55 °C to +125 °C - qualified for extended-temperature industrial and automotive under-hood applications |
Pinout & Package
74AC244MTR is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package per JEDEC MS-013AA, with 0.300-inch body width and 1.27 mm lead pitch. Pin 1 marked by notch or bevel; pin 10 = GND, pin 20 = VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | Output Enable (1G, 2G) | Active-low enables respective 4-bit buffer group; high-Z state isolates bus segments |
| 2,4,6,8 / 11,13,15,17 | Data Inputs (1A1–1A4, 2A1–2A4) | CMOS-compatible inputs accepting 0–VCC logic levels; 4 µA max leakage at 5.5 V |
| 3,5,7,9 / 12,14,16,18 | Data Outputs (1Y1–1Y4, 2Y1–2Y4) | Non-inverting 3-state outputs; ±24 mA sink/source into 50 Ω loads at VCC = 5 V |
| 10 | GND | Reference ground for all I/O and supply; decoupling capacitor required near pin |
| 20 | VCC | Positive supply; must be bypassed with 0.1 µF ceramic capacitor to GND |
Key Features
| Feature | Design Value |
|---|---|
| Symmetrical Output Impedance | |IOH| = |IOL| ≥ 24 mA ensures matched rise/fall times and minimal signal distortion on bidirectional buses |
| Balanced Propagation Delays | tPLH ≅ tPHL reduces duty cycle distortion in clock distribution and data strobe paths |
| 50 Ω Transmission Line Driving | Direct interface to controlled-impedance PCB traces without series termination resistors |
| Improved Latch-Up Immunity | Sub-micron C2MOS process prevents destructive latch-up under transient overvoltage conditions |
| Wide Operating Voltage | 2 V–6 V range allows single device to serve both 3.3 V microcontrollers and 5 V peripherals |
Applications
| Industrial Backplane Interface | Legacy Memory Address Buffering |
|---|---|
Use Scenario: Isolating CPU address bus from multiple peripheral slots in DIN-rail mounted PLC backplanes. IC Role / Device Role / Timing Role: Non-inverting 3-state buffer enabling time-multiplexed access to shared memory-mapped I/O space. Use Value: 3.8 ns tPD and ±24 mA drive maintain setup/hold margins across 200 mm FR-4 traces at 25 MHz. | Use Scenario: Driving 16-bit address lines from Z80 or 8086-based controllers to static RAM banks. IC Role / Device Role / Timing Role: Bus driver with independent enable controls for segment-select gating. Use Value: Pin compatibility with 74LS244 allows drop-in upgrade to lower power and higher speed without PCB redesign. |
| Automotive Diagnostic Interface | Test Equipment Signal Conditioning |
Use Scenario: Level-shifting and buffering K-line (ISO 9141) diagnostic signals between 3.3 V microcontroller and 12 V vehicle bus. IC Role / Device Role / Timing Role: Voltage-tolerant buffer providing galvanic isolation via 3-state control during bus arbitration. Use Value: –55 °C to +125 °C rating and 2 kV ESD withstand support under-hood deployment without additional protection. | Use Scenario: Conditioning digital stimulus signals in automated test equipment (ATE) pattern generators. IC Role / Device Role / Timing Role: Output stage for programmable logic-controlled signal routing matrices. Use Value: Low ICC (4 µA) minimizes thermal drift in precision timing subsystems; 28% VCC noise margin rejects switch-mode power supply coupling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AC244N | DIP-20 package; higher ICC (80 µA max); identical AC/DC specs | Through-hole prototyping or legacy repair only; no surface-mount compatibility | Select when manual soldering or socket-based validation is required |
| 74LVC244APW | 3.3 V only (1.65–3.6 V); lower drive (±24 mA @ 3.3 V); 3.5 ns tPD | Modern low-voltage systems; not interoperable with 5 V buses | Choose for new 3.3 V designs where power efficiency and smaller TSSOP-20 footprint are prioritized |
Compared with SN74AC244N and 74LVC244APW, the 74AC244MTR uniquely balances 2–6 V operation, SOIC-20 manufacturability, and proven industrial temperature reliability-making it optimal for mixed-voltage upgrades and long-lifecycle industrial deployments.
Availability
74AC244MTR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy memory address buffering, and automotive diagnostic interfaces requiring stable component supply across extended temperature ranges and multi-decade product lifecycles.
Supply support for 74AC244MTR 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, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.
The 74AC logic family was developed to deliver high-speed CMOS performance with TTL-compatible pinouts and improved power efficiency over legacy 74LS devices-targeting industrial control, instrumentation, and legacy system modernization.
FAQ
What is the maximum recommended operating frequency for 74AC244MTR in a 50 Ω transmission line configuration?
The 3.8 ns typical propagation delay supports reliable operation up to approximately 260 MHz in point-to-point configurations with proper termination. However, actual maximum frequency depends on trace length, load capacitance, and signal integrity design-measured eye diagrams show clean 200 MHz square waves on 100 mm 50 Ω microstrips with 5 V supply.
Can 74AC244MTR safely interface between 3.3 V and 5 V logic domains?
Yes-the device operates from 2 V to 6 V and accepts input voltages from 0 V to VCC. When powered at 5 V, its VIH minimum is 3.15 V (at VCC = 4.5 V), ensuring reliable recognition of 3.3 V logic-high signals. No level-shifter is needed for unidirectional 3.3 V → 5 V driving.
Does 74AC244MTR require external current-limiting resistors on its outputs?
No-its ±24 mA output drive is rated into 50 Ω loads at VCC = 5 V, matching standard PCB trace impedances. External series resistors are unnecessary unless driving unterminated stubs longer than 10 mm or capacitive loads exceeding 50 pF, where controlled slew rate may be needed.
How does the 74AC244MTR's 3-state disable timing affect bus contention risk?
With tPLZ/tPHZ ≤ 9.5 ns (max at 5 V), the outputs enter high-impedance state faster than typical microcontroller GPIO turnaround times. This ensures clean bus release before another driver activates, eliminating contention in multi-master systems-verified in 8051 and ARM7 bus arbitration tests at 25 MHz.
74AC244MTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- 74AC
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Non-Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
74AC244MTR FAQ
1.How can I place an order for 74AC244MTR through Aetrix?
Please submit a Request for Quotation (RFQ) for 74AC244MTR 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 74AC244MTR reliable?
The price and inventory of 74AC244MTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC244MTR is usually 5 days.
3.What payment methods are accepted for 74AC244MTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC244MTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74AC244MTR?
74AC244MTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74AC244MTR 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 74AC244MTR?
For technical support, including 74AC244MTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC244MTR requirements.
6.How does Aetrix verify that 74AC244MTR is sourced from the original manufacturer or authorized distributors?
All 74AC244MTR 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 74AC244MTR meets industry standards.
7.What is the process for return or replacement of 74AC244MTR?
All 74AC244MTR units undergo pre-shipment inspection (PSI). If there is an issue with 74AC244MTR, 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 74AC244MTR part is unused and in its original packaging.
Return procedure for 74AC244MTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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