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Texas Instruments SN74ALS244CNS
- Part No.:
- SN74ALS244CNS
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS244CNS.pdf
- Description:
- PROTOTYPE
- Quantity:
- Payment:
- Shipping:
Inventory:3,188
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Product details
Overview
SN74ALS244CNS from Texas Instruments is an octal non-inverting buffer/line driver with 3-state outputs, designed for memory address driving, bus interfacing, and clock distribution in TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers 24 mA low-level output current, features pnp input structure for reduced DC loading, and is rated for 0°C to 70°C operation in a 20-pin plastic DIP (N) package.
For engineers reviewing the SN74ALS244CNS datasheet, SN74ALS244CNS pinout, SN74ALS244CNS application, or SN74ALS244CNS equivalent, key selection criteria include its 3-state enable timing (tPZL ≤ 24 ns), VOL ≤ 0.4 V at IOL = 24 mA, and compatibility with legacy 74ALS bus architectures requiring symmetrical active-low OE control and high fan-out drive capability.
Technical Context
This device implements eight independent non-inverting buffers, each with dual active-low 3-state enable inputs (1OE and 2OE) controlling two groups of four outputs. The pnp-based input stage minimizes input current draw, enabling high-density address buffering without excessive bus loading.
Its logic function follows a standard truth table: output Y = A when OE = L; output is high-impedance (Z) when OE = H. Propagation delays are specified at CL = 50 pF with R1 = R2 = 500 Ω, supporting reliable timing in synchronous bus systems up to ~100 MHz equivalent edge rates.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with standard 5 V TTL rails and tolerates ±10% supply variation. |
| Low-Level Output Current | 24 mA - Supports direct drive of multiple TTL inputs or termination resistors on shared buses. |
| Output Disable Time (tPZL) | 24 ns max - Enables fast bus release for time-critical arbitration or multiplexing sequences. |
| Input Voltage Thresholds | VIL = 0.8 V, VIH = 2.0 V - Matches standard TTL logic levels for seamless integration into legacy systems. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial-grade industrial and computing applications. |
| Propagation Delay (tPHL) | 10 ns max - Allows use in high-speed address/data paths with sub-100 ns cycle timing budgets. |
| Quiescent Supply Current | 24 mA max (outputs disabled) - Predictable power budgeting during 3-state idle periods. |
Pinout & Package
SN74ALS244CNS is housed in a 20-pin plastic dual in-line package (PDIP-N), 300-mil width, with standard through-hole mounting and 0.1-inch pin spacing. Pin 1 is located at the top-left corner adjacent to the notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE | Group 1 Output Enable (active-low) | Controls Y1–Y4; drives all four outputs high-impedance when high. |
| 1A1–1A4 | Group 1 Inputs | Non-inverting data inputs for outputs Y1–Y4. |
| 2OE | Group 2 Output Enable (active-low) | Controls Y5–Y8; independent enable for second buffer quad. |
| 2A1–2A4 | Group 2 Inputs | Non-inverting data inputs for outputs Y5–Y8. |
| 1Y1–1Y4, 2Y1–2Y4 | Buffer Outputs | 3-state non-inverting outputs; sink up to 24 mA per pin. |
| GND (Pin 10) | Ground Reference | Primary return path for logic and output currents; must be low-impedance. |
| VCC (Pin 20) | Power Supply | 5 V supply connection; requires local 0.1 µF ceramic decoupling. |
Key Features
| Feature | Design Value |
|---|---|
| 3-State Outputs | Enables bidirectional or shared-bus operation without external isolation components. |
| pnp Input Structure | Reduces input current to ≤ –0.1 mA, minimizing loading on preceding drivers or microcontroller pins. |
| Symmetrical Active-Low OE | Dual OE inputs (1OE, 2OE) allow independent control of two 4-bit buffer groups for flexible bus partitioning. |
| TTL-Compatible Logic Levels | VIH = 2.0 V and VIL = 0.8 V ensure interoperability with standard 74LS/74ALS/74F families. |
| High Fan-Out Capability | Each output drives ≥20 74ALS loads, supporting dense memory address or data bus expansion. |
Applications
| Memory Address Buffering | System Bus Interface |
|---|---|
Use Scenario: Driving 16-bit or wider memory address buses in microprocessor-based systems such as industrial controllers or retro-computing platforms. IC Role / Device Role / Timing Role: Non-inverting buffer with 3-state control, isolating CPU address lines from memory module inputs during DMA or refresh cycles. Use Value: Prevents address bus contention and ensures clean signal integrity across long PCB traces with up to 24 mA drive strength per line. | Use Scenario: Interfacing between different voltage or timing domains on a shared data or control bus in embedded instrumentation. IC Role / Device Role / Timing Role: Bidirectional bus driver enabling controlled data flow between master and peripheral ICs using OE-gated 3-state outputs. Use Value: Eliminates need for discrete transceivers; supports hot-swap-safe bus arbitration via precise tPZL/tPHZ timing control. |
| Clock Distribution | Legacy TTL System Expansion |
Use Scenario: Distributing synchronized clock signals to multiple TTL logic blocks while maintaining edge fidelity and skew control. IC Role / Device Role / Timing Role: Low-skew, non-inverting clock buffer with matched propagation delay (tPLH/tPHL ≤ 10 ns) across all eight channels. Use Value: Reduces clock jitter accumulation in multi-stage timing chains and sustains setup/hold margins for downstream flip-flops. | Use Scenario: Upgrading or repairing vintage test equipment, PLCs, or military avionics where original 74ALS parts are obsolete or unavailable. IC Role / Device Role / Timing Role: Drop-in replacement for SN74ALS244CN in existing PDIP footprints, preserving board layout and firmware compatibility. Use Value: Maintains identical AC/DC electrical behavior and pinout, avoiding redesign while meeting RoHS compliance via NIPDAU lead finish. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS244CN | Same die, identical electrical specs, same PDIP-20 package; differs only in part marking and packaging format (tube vs. tape-and-reel). | No functional difference; both rated for 0°C to 70°C, 24 mA IOL, and share identical timing and DC parameters. | Select SN74ALS244CN for tube-packaged volume orders; SN74ALS244CNSR preferred for automated SMT assembly. |
| SN74AS244AN | Faster propagation delay (6.2 ns max vs. 10 ns), higher IOL (48 mA), but increased ICC (up to 90 mA) and stricter VIH/VIL thresholds (VIH = 2.0 V, VIL = 0.8 V unchanged). | Better suited for high-speed bus backplanes or clock trees where timing margin is critical; less tolerant of marginal input noise. | Choose SN74AS244AN only when sub-7 ns delay is required and power budget allows +2.5× quiescent current; otherwise SN74ALS244CNS offers superior noise immunity and lower power. |
Compared with SN74ALS244CN, SN74ALS244CNS provides identical functionality in tape-and-reel form for automated placement, while SN74AS244AN trades higher power and reduced noise margin for significantly faster switching-making it suitable only where speed outweighs robustness and efficiency.
Availability
SN74ALS244CNS is available at Aetrix Electronics and suitable for memory address buffering, system bus interface, and clock distribution applications requiring stable component supply, long-term obsolescence management, and RoHS-compliant sourcing.
Supply support for SN74ALS244CNS 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 over 90 years of innovation in industrial, automotive, and communications markets.
The SN74ALS244CNS belongs to TI's legacy 74ALS logic family, engineered for high-speed, low-power TTL-compatible operation in memory subsystems and bus-oriented digital systems deployed from the 1980s onward.
FAQ
What is the maximum operating temperature range for the SN74ALS244CNS?
The SN74ALS244CNS is characterized for operation from 0°C to 70°C, making it suitable for commercial and industrial environments where ambient temperatures remain within this range. It does not meet extended or military temperature specifications like the SN54ALS244C variant, which operates from –55°C to 125°C.
Does the SN74ALS244CNS support true bidirectional data flow?
No, the SN74ALS244CNS is a unidirectional non-inverting buffer with 3-state outputs. While its outputs can be disabled to allow other devices to drive the same bus line, the device itself has no internal direction control or input/output pin reversal-it functions strictly as an A → Y driver with OE-gated output enable.
Can the SN74ALS244CNS be used as a direct replacement for SN74LS244 in existing designs?
Yes, the SN74ALS244CNS is pin-compatible and electrically compatible with SN74LS244, offering improved speed (10 ns vs. 15 ns typical delay), lower power consumption, and enhanced noise immunity due to tighter VIH/VIL thresholds and pnp input structure-making it a recommended upgrade path for legacy LS-based systems.
What is the recommended decoupling strategy for the SN74ALS244CNS?
Place a 0.1 µF ceramic capacitor between VCC (Pin 20) and GND (Pin 10) as close as possible to the device body. For boards with multiple SN74ALS244CNS units, add one bulk 4.7 µF tantalum or aluminum electrolytic capacitor per 5–10 devices near the power entry point to suppress low-frequency supply ripple.
Is the SN74ALS244CNS RoHS compliant?
Yes, the SN74ALS244CNS uses NiPdAu (NIPDAU) lead finish and is RoHS compliant, as confirmed by TI's packaging documentation. It meets EU Directive 2011/65/EU requirements and carries appropriate marking for restricted substance compliance in commercial production.
SN74ALS244CNS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.209", 5.30mm 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:
- 15mA, 48mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74ALS244CNS FAQ
1.How can I place an order for SN74ALS244CNS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS244CNS 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 SN74ALS244CNS reliable?
The price and inventory of SN74ALS244CNS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS244CNS is usually 5 days.
3.What payment methods are accepted for SN74ALS244CNS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS244CNS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS244CNS?
SN74ALS244CNS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS244CNS 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 SN74ALS244CNS?
For technical support, including SN74ALS244CNS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS244CNS requirements.
6.How does Aetrix verify that SN74ALS244CNS is sourced from the original manufacturer or authorized distributors?
All SN74ALS244CNS 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 SN74ALS244CNS meets industry standards.
7.What is the process for return or replacement of SN74ALS244CNS?
All SN74ALS244CNS units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS244CNS, 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 SN74ALS244CNS part is unused and in its original packaging.
Return procedure for SN74ALS244CNS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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