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Texas Instruments SN74AS244DW
- Part No.:
- SN74AS244DW
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74AS244DW.pdf
- Description:
- BUS DRIVER, AS SERIES
- Quantity:
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- Shipping:
Inventory:1,000
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Product details
Overview
SN74AS244DW from Texas Instruments is an octal non-inverting buffer/line driver with 3-state outputs, designed for memory address driving and bus interfacing in TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers 64 mA low-level output current (IOL), supports 0°C to 70°C ambient operation, and features PNP input structure for reduced DC loading - used in industrial control backplanes and legacy data acquisition systems.
For engineers reviewing the SN74AS244DW datasheet, SN74AS244DW pinout, SN74AS244DW application, or SN74AS244DW equivalent, key selection criteria include guaranteed 3-state leakage (±50 µA), sub-10 ns propagation delay (tPLH/tPHL ≤ 6.2 ns), high-current drive capability, and compatibility with standard 20-pin SOIC (DW) packaging for PCB space-constrained designs.
Technical Context
This device implements two independent 4-bit non-inverting buffer groups, each controlled by a dedicated active-low 3-state enable input (1G and 2G). Each output can sink up to 64 mA while maintaining VOL ≤ 0.55 V at VCC = 4.5 V, enabling direct interface with heavy capacitive loads or multiple TTL inputs.
Its AS logic family delivers faster switching than ALS variants: tPZH/tPZL ≤ 9 ns and tPHZ/tPLZ ≤ 6.5 ns under CL = 50 pF, R1/R2 = 500 Ω, making it suitable for high-speed address/data bus buffering where output enable timing and bus release speed are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures stable operation across standard 5 V ±10% supply rails without regulation overhead. |
| IOL (max) | 64 mA - enables direct drive of up to 20 standard TTL loads or termination-resistor networks on shared buses. |
| tPLH / tPHL | ≤ 6.2 ns - guarantees sub-7 ns signal propagation from input to enabled output, critical for synchronous bus timing margins. |
| IOZL / IOZH | ±50 µA - specifies tight 3-state off-state leakage, minimizing unintended bus contention during disable transitions. |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade embedded systems including instrumentation and office equipment. |
| VIL / VIH | 0.8 V / 2.0 V - TTL-compatible input thresholds ensure robust noise immunity and seamless integration with legacy 5 V logic families. |
Pinout & Package
SN74AS244DW uses a 20-pin SOIC (Small Outline Integrated Circuit) package (DW suffix), 7.5 mm wide, with standard 0.050″ pitch. Pin numbering follows JEDEC MS-013, top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1G, 2G (Active-Low Enable) | Independent group enables: pulling low activates corresponding Y outputs; high-Z when high. |
| 2–5, 12–15 | 1A1–1A4, 2A1–2A4 (Inputs) | Non-inverting data inputs for each buffer channel; PNP structure reduces input current draw. |
| 6–9, 16–19 | 1Y1–1Y4, 2Y1–2Y4 (Outputs) | 3-state buffered outputs; sink up to 64 mA while holding VOL ≤ 0.55 V at full load. |
| 10 | GND | Power ground reference for all internal circuitry and output drivers. |
| 20 | VCC | Positive supply rail (4.5–5.5 V); decoupling capacitor required near pin for transient current stability. |
Key Features
| Feature | Design Value |
|---|---|
| High-current 3-state outputs | 64 mA sink capability per output maintains VOL ≤ 0.55 V, eliminating need for external bus drivers in medium-load applications. |
| Low propagation delay | tPLH/tPHL ≤ 6.2 ns ensures minimal timing skew across 8 channels, preserving setup/hold margins in synchronous bus architectures. |
| PNP input structure | Reduces input current to ≤ –1 mA (IIL), lowering system-level DC loading and simplifying pull-up resistor design on shared control lines. |
| Tight 3-state leakage control | IOZL/IOZH ≤ ±50 µA prevents false logic states during bus arbitration or hot-swap transitions in multi-driver environments. |
Applications
| Memory Address Buffering | Industrial Backplane Interface |
|---|---|
Use Scenario: Driving 16-bit address bus between microprocessor and SRAM/ROM in legacy industrial controllers. IC Role / Device Role / Timing Role: Non-inverting octal buffer with independent 3-state enables isolates CPU address lines from memory module loading and enables bank-select multiplexing. Use Value: 64 mA IOL drives 20+ TTL loads per output; sub-7 ns delay preserves address valid window for 12 MHz bus cycles. |
Use Scenario: Interfacing PLC CPU modules to distributed I/O racks over parallel backplane wiring. IC Role / Device Role / Timing Role: Bus driver providing level-shifted, current-boosted signals between isolated controller and field-side peripherals. Use Value: Dual-group enable (1G/2G) allows staggered activation to reduce simultaneous switching noise on shared VCC/GND planes. |
| Data Acquisition Bus Driver | Legacy Test Equipment Signal Routing |
Use Scenario: Multiplexing analog-to-digital converter channel select lines and status flags across shared digital bus. IC Role / Device Role / Timing Role: 3-state line driver enabling bidirectional control of multi-drop sensor addressing and result readback paths. Use Value: ±50 µA 3-state leakage prevents crosstalk between inactive channels; PNP inputs minimize bias current on high-impedance mux control lines. |
Use Scenario: Replacing failed buffers in 1980s-era automated test equipment requiring exact form-fit-function replacement. IC Role / Device Role / Timing Role: Drop-in compatible octal buffer supporting original board layout, timing, and voltage levels without redesign. Use Value: Pinout and AC/DC specs match SN74ALS244B but with improved speed and drive strength - verified for backward-compatible use in calibrated instruments. |
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 |
|---|---|---|---|
| SN74ALS244BN | Slower tPLH/tPHL (≤10 ns), lower IOL (24 mA), same 20-pin DIP (N) package; no SOIC option. | Acceptable for low-speed (<5 MHz) memory expansion where drive strength and layout density are secondary. | Choose if legacy through-hole assembly or cost sensitivity outweighs speed and current requirements. |
| SN74F244N | F-family variant: tPLH/tPHL ≤ 8.5 ns, IOL = 20 mA, higher ICC (up to 90 mA), same 20-pin DIP footprint. | Suitable for general-purpose bus buffering where moderate speed suffices and SOIC is not required. | Select when existing F-series inventory exists or thermal budget permits higher quiescent power. |
Compared with SN74ALS244BN and SN74F244N, the SN74AS244DW provides superior speed (≤6.2 ns vs. ≥8.5 ns), highest drive strength (64 mA), and modern SOIC packaging - making it optimal for space-constrained, high-reliability commercial systems needing precise timing and bus loading control.
Availability
SN74AS244DW is available at Aetrix Electronics and suitable for industrial control backplanes, legacy data acquisition systems, and commercial-grade instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for SN74AS244DW 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and consumer market reach.
The SN74AS244DW belongs to TI's advanced Schottky (AS) TTL logic family, engineered for high-speed, high-drive bus interfacing in commercial temperature environments - targeting reliability-critical upgrades of legacy 5 V systems.
FAQ
What is the maximum output sink current specified for SN74AS244DW?
The SN74AS244DW is rated for a maximum low-level output current (IOL) of 64 mA per output, measured at VCC = 4.5 V and ensuring VOL ≤ 0.55 V. This specification is confirmed in the "Electrical Characteristics" table for SN74AS244 on page 4 of the SDAS142 datasheet, and applies across the full 0°C to 70°C operating range.
Does SN74AS244DW support 3.3 V operation?
No, SN74AS244DW is not rated for 3.3 V operation. Its absolute maximum VCC is 7 V, but the recommended operating range is strictly 4.5 V to 5.5 V. Input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output drive characteristics are optimized for 5 V TTL compatibility; operation below 4.5 V may result in undefined timing or insufficient noise margin.
Is SN74AS244DW pin-compatible with SN74ALS244B?
Yes, SN74AS244DW is pin-compatible with SN74ALS244B in the same DW (SOIC) package. Both share identical 20-pin SOIC footprints, identical pin functions (1G, 1A1–1A4, 1Y1–1Y4, etc.), and matching power/ground locations. However, SN74AS244DW offers faster propagation delays and higher output drive - verified via TI's logic family cross-reference documentation.
What is the 3-state enable behavior of SN74AS244DW?
SN74AS244DW features two active-low 3-state enable inputs: 1G controls outputs 1Y1–1Y4, and 2G controls 2Y1–2Y4. When either G input is high, its associated Y outputs enter high-impedance (Hi-Z) state with leakage ≤ ±50 µA. When low, outputs actively drive according to their respective A inputs - confirmed in the logic symbol and "Electrical Characteristics" section of the datasheet.
Can SN74AS244DW be used in place of SN74LS244?
SN74AS244DW can functionally replace SN74LS244 in most 5 V systems, offering faster speed (≤6.2 ns vs. ≤25 ns), higher drive (64 mA vs. 8 mA), and lower input current. However, due to higher ICC (up to 90 mA vs. ~25 mA), thermal and power delivery design must be re-evaluated. The pinout and logic behavior are identical, making it a validated upgrade path per TI's AS/LS migration guidance.
SN74AS244DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SN74AS244DW FAQ
1.How can I place an order for SN74AS244DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS244DW 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 SN74AS244DW reliable?
The price and inventory of SN74AS244DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS244DW is usually 5 days.
3.What payment methods are accepted for SN74AS244DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS244DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS244DW?
SN74AS244DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS244DW 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 SN74AS244DW?
For technical support, including SN74AS244DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS244DW requirements.
6.How does Aetrix verify that SN74AS244DW is sourced from the original manufacturer or authorized distributors?
All SN74AS244DW 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 SN74AS244DW meets industry standards.
7.What is the process for return or replacement of SN74AS244DW?
All SN74AS244DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS244DW, 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 SN74AS244DW part is unused and in its original packaging.
Return procedure for SN74AS244DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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