My Inquiry
My Account
Texas Instruments SN74AS244N
- Part No.:
- SN74AS244N
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74AS244N.pdf
- Description:
- BUS DRIVER, AS SERIES
- Quantity:
- Payment:
- Shipping:
Inventory:12,548
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74AS244N 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 0°C to 70°C, supports 5 V supply, delivers up to 64 mA low-level output current, and achieves propagation delays as low as 2 ns (tPLH/tPHL) under 50 pF load.
For engineers reviewing the SN74AS244N datasheet, SN74AS244N pinout, SN74AS244N application, or SN74AS244N equivalent, this page provides verified functional specifications, package mapping to 20-pin PDIP (N), real-world timing behavior, and validated drop-in alternatives for legacy TTL bus interface designs.
Technical Context
The SN74AS244N implements two independent 4-bit groups (1A–1Y and 2A–2Y), each controlled by a dedicated active-low enable input (1G, 2G). Its AS (Advanced Schottky) logic family delivers higher speed and lower power than standard TTL while maintaining compatible voltage thresholds (VIH = 2 V, VIL = 0.8 V).
Each output transitions to high-impedance when its respective G input is high, enabling bidirectional bus sharing without external isolation. PNP input structure reduces DC loading on driving sources, improving fan-out capability in dense address/data bus configurations.
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. |
| IOL Max | 64 mA - Supports direct drive of multiple TTL inputs or moderate capacitive loads (e.g., 10–15 pF per stub). |
| tPLH / tPHL | 2 ns min / 6.2 ns max - Enables reliable 100+ MHz bus clocking in short trace layouts. |
| VIH / VIL | 2.0 V / 0.8 V - Fully compatible with TTL and LS logic output levels; no level-shifting required. |
| Operating Temp | 0°C to 70°C - Qualified for commercial-grade embedded control and instrumentation applications. |
| ICC (Outputs Low) | 60–90 mA - Reflects high-drive capability; requires adequate PCB copper and thermal relief in sustained active mode. |
Pinout & Package
SN74AS244N is supplied in a 20-pin plastic dual in-line package (PDIP), 300-mil width, with standard through-hole mounting and JEDEC MO-016AC outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1G | Group 1 Output Enable (active-low) | Drives all Y1–Y4 outputs into high-Z when logic high; enables buffering only when low. |
| 1A1–1A4 | Group 1 Input Signals | Non-inverting data inputs for outputs Y1–Y4; accept standard TTL voltage levels. |
| 1Y1–1Y4 | Group 1 Output Signals | Buffered, non-inverting outputs with 3-state control; sink up to 64 mA each. |
| 2G | Group 2 Output Enable (active-low) | Independent control for Y5–Y8; allows split-bus or staggered enable sequencing. |
| 2A1–2A4 | Group 2 Input Signals | Second set of non-inverting inputs; electrically isolated from Group 1 except shared VCC/GND. |
| 2Y1–2Y4 | Group 2 Output Signals | Match Group 1 drive strength and timing; support parallel or mirrored bus segments. |
| 10 | GND | Signal reference and return path for all I/O and internal logic; must be low-inductance connection. |
| 20 | VCC | +5 V power supply; requires local 0.1 µF ceramic decoupling adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| AS Logic Family Speed | 6.2 ns max propagation delay enables faster bus cycles than ALS or LS variants (e.g., SN74ALS244B). |
| 64 mA Sink Capability | Directly drives 20+ standard TTL loads or terminates unterminated microstrip traces up to ~2 inches. |
| Dual Independent 4-Bit Groups | Enables selective bus segment control-e.g., address vs. data lines-with separate enable timing. |
| PNP Input Structure | Reduces input current to ≤1 mA (IIL = –1 mA), lowering driver-stage loading and power dissipation. |
| 3-State Output Compatibility | Meets IEEE Std 1114-1987 for bus transceivers; supports wired-OR arbitration and hot-swap-safe insertion. |
Applications
| Memory Address Buffering | Microprocessor Bus Interface |
|---|---|
Use Scenario: Driving 16-bit address bus from a Z80 or 8085 CPU to multiple memory chips with long trace runs. IC Role / Device Role / Timing Role: Non-inverting buffer with 3-state control synchronizes with CPU ALE signal to isolate address during data phase. Use Value: 64 mA drive ensures clean edges across 100+ mm PCB traces; 2 ns delay margin supports >10 MHz bus clocks. | Use Scenario: Isolating peripheral I/O address decoding logic from shared data bus in industrial PLC backplanes. IC Role / Device Role / Timing Role: Bidirectional bus driver enabling read/write separation via independent 1G/2G enables. Use Value: Dual-group architecture eliminates need for discrete enable logic; 3-state leakage <50 µA prevents bus contention during reset. |
| Legacy System Bus Expansion | TTL-Level Signal Repeater |
Use Scenario: Extending ISA or S-100 bus segments in retrocomputing restoration projects with signal integrity preservation. IC Role / Device Role / Timing Role: Active repeater regenerating degraded address/data waveforms between chassis segments. Use Value: AS-family propagation delay consistency (±0.5 ns) avoids setup/hold violations across multi-segment timing budgets. | Use Scenario: Restoring logic levels across noisy industrial sensor wiring where cable capacitance exceeds 200 pF. IC Role / Device Role / Timing Role: Unidirectional line driver boosting TTL signals over twisted-pair cabling to remote displays or actuators. Use Value: 64 mA sink current maintains VOL < 0.55 V even at end-of-cable load, ensuring noise margin >0.7 V. |
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 | Lower drive (24 mA IOL), slower (10 ns max tPHL), same pinout and voltage specs. | Suitable for low-speed, low-power legacy boards where heat or noise is critical. | Choose when board layout lacks thermal margin or when driving only LS loads. |
| 74F244N | Fast TTL variant: 3.5 ns max tPHL, 20 mA IOL, higher ICC (100 mA), same 20-pin DIP. | Better for high-frequency clock distribution but less robust for heavy bus loading. | Prefer when propagation delay dominates design, not drive strength. |
Compared with SN74ALS244BN and 74F244N, the SN74AS244N uniquely balances high-speed switching (≤6.2 ns) with strong output drive (64 mA), making it optimal for legacy bus interfaces requiring both timing margin and fan-out capability without redesigning enable logic or adding external drivers.
Availability
SN74AS244N is available at Aetrix Electronics and suitable for memory address buffering, microprocessor bus interface, and legacy system bus expansion requiring stable component supply and long-term obsolescence management.
Supply support for SN74AS244N 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, delivering analog, embedded processing, and logic solutions with industry-leading quality and longevity.
The SN74AS244N belongs to TI's Advanced Schottky TTL logic family, engineered for high-speed, low-power bus interfacing in industrial control, test equipment, and retrocomputing systems where reliability and pin compatibility with legacy designs are essential.
FAQ
What is the maximum operating temperature range for the SN74AS244N?
The SN74AS244N is characterized for operation from 0°C to 70°C, meeting commercial-grade environmental requirements. This range is explicitly defined in the July 1987 revision of the SDAS142 datasheet and applies to all SN74AS244 variants in N-package. Operation outside this range may result in undefined timing or output behavior and is not guaranteed by Texas Instruments specifications.
Does the SN74AS244N support true bidirectional data flow?
No, the SN74AS244N is a unidirectional octal buffer with non-inverting outputs. It does not include internal direction control or bus transceiver logic. Data flows strictly from A-inputs to Y-outputs within each group; bidirectional operation requires pairing with complementary devices like the SN74AS245N or external control logic.
What is the recommended decoupling for the SN74AS244N?
A 0.1 µF ceramic capacitor placed as close as possible to pin 20 (VCC) and pin 10 (GND) is required for stable operation. The SN74AS244N's fast edge rates (sub-1 ns rise/fall) induce significant transient current; insufficient decoupling causes VCC droop and increased ground bounce, degrading timing margins and increasing VOL uncertainty.
Can the SN74AS244N replace the SN74LS244N in an existing design?
Yes, the SN74AS244N is a direct pin-compatible upgrade for SN74LS244N, offering faster propagation (6.2 ns vs. 25 ns), higher drive (64 mA vs. 8 mA), and identical 20-pin PDIP footprint. However, its higher ICC (up to 90 mA) and sharper edges require verification of power delivery and signal integrity in the original layout.
Is the SN74AS244N RoHS compliant?
The original SN74AS244N (manufactured pre-2006) is not RoHS compliant, as it contains lead in the PDIP package finish and solder composition. Texas Instruments does not offer a RoHS-compliant re-engineered version of this specific part number; modern alternatives like SN74LVC244A require PCB redesign due to different voltage and package constraints.
SN74AS244N 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:
- -
SN74AS244N FAQ
1.How can I place an order for SN74AS244N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS244N 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 SN74AS244N reliable?
The price and inventory of SN74AS244N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS244N is usually 5 days.
3.What payment methods are accepted for SN74AS244N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS244N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS244N?
SN74AS244N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS244N 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 SN74AS244N?
For technical support, including SN74AS244N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS244N requirements.
6.How does Aetrix verify that SN74AS244N is sourced from the original manufacturer or authorized distributors?
All SN74AS244N 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 SN74AS244N meets industry standards.
7.What is the process for return or replacement of SN74AS244N?
All SN74AS244N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS244N, 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 SN74AS244N part is unused and in its original packaging.
Return procedure for SN74AS244N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74AS244N Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
