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Texas Instruments SN74ALS1244ADW
- Part No.:
- SN74ALS1244ADW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS1244ADW.pdf
- Description:
- IC BUF NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,776
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Product details
Overview
SN74ALS1244ADW from Texas Instruments is a dual 4-bit noninverting 3-state buffer/driver IC designed for memory address and bus driving in TTL-compatible systems. It features two independent 4-bit channels (1A–1Y and 2A–2Y), 20-pin SOIC (DW) package, ±15 mA output drive capability, and operates over 0°C to 70°C with 4.5 V–5.5 V supply. It is used in legacy industrial control backplanes and parallel data buses requiring low-power ALS logic.
For engineers reviewing the SN74ALS1244ADW datasheet, SN74ALS1244ADW pinout, SN74ALS1244ADW application, or SN74ALS1244ADW equivalent, key selection criteria include 3-state enable timing (tPZH ≤ 13 ns), input pnp structure reducing DC loading, and compatibility with 5-V TTL bus architectures requiring octal buffering with independent channel enables.
Technical Context
The SN74ALS1244ADW implements two independent 4-bit noninverting buffer sections, each with dedicated 3-state output enable (1OE, 2OE). Its pnp-input structure lowers input current draw versus standard TTL, improving fanout in dense address-bus applications. Outputs are fully buffered totem-pole with symmetric ±15 mA drive capability under 5-V operation.
Propagation delays are tightly specified: tPLH/tPHL ≤ 14 ns at CL = 50 pF, and 3-state enable/disable times (tPZH/tPLZ ≤ 13 ns, tPZL/tPHZ ≤ 22 ns) support high-speed bus arbitration. The device is not designed for hot-swap or live-insertion - outputs must be disabled before voltage transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS (Advanced Low-Power Schottky) - balances speed (≤14 ns propagation) and power (ICC ≤ 17 mA active) better than standard LS. |
| Supply Voltage | 4.5 V to 5.5 V - compatible with regulated 5-V TTL rails; no operation below 4.5 V guaranteed. |
| Output Drive | ±15 mA (IOL = 16 mA, IOH = −15 mA) - sufficient to drive 50-pF loads across 20-cm PCB traces in backplane applications. |
| 3-State Enable Delay | tPZH ≤ 13 ns - ensures fast bus release for time-critical memory read cycles in 8086/80286-era systems. |
| Input Structure | pnp-based inputs - reduce DC input loading to ≤0.1 mA per pin, enabling >20-fanout on shared address lines. |
| Operating Temperature | 0°C to 70°C - commercial-grade rating; not qualified for extended industrial or automotive environments. |
| Package | 20-pin SOIC (DW) - 7.5-mm body width, 1.27-mm pitch; RoHS-compliant with Cu/NiPdAu finish and MSL Level-1 rating. |
Pinout & Package
SN74ALS1244ADW uses a 20-pin SOIC (DW) package with standard 1.27-mm pitch and 7.5-mm body width. Pin numbering follows JEDEC MS-013, with Pin 1 located at the top-left corner (notch or dot indicator).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low 3-state enable inputs - disable respective 4-bit output groups (1Y1–1Y4 or 2Y1–2Y4) when high. |
| 2–5, 12–15 | 1A1–1A4, 2A1–2A4 | Noninverting data inputs - directly pass logic states to corresponding outputs when enabled. |
| 18, 16, 14, 12, 11, 13, 15, 17 | 1Y1–1Y4, 2Y1–2Y4 | Buffered noninverting outputs - drive bus lines or memory address registers; high-impedance when OE = HIGH. |
| 10 | GND | Ground reference for all internal circuitry and output stages. |
| 20 | VCC | +5-V supply rail - powers all logic and output drivers; decoupling capacitor required within 1 cm. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit buffers | Enables separate control of two address/data sub-buses (e.g., upper/lower byte) without inter-channel crosstalk. |
| pnp input structure | Reduces input current to ≤0.1 mA per pin, minimizing loading on upstream drivers and extending fanout beyond 20. |
| 3-state outputs with fast enable/disable | tPZH ≤ 13 ns and tPLZ ≤ 16 ns allow precise bus arbitration in multi-master systems with minimal bus contention window. |
| ALS logic family optimization | Delivers 14 ns propagation delay at 17 mA ICC - 30% faster than LS with comparable power vs. AS family's higher current draw. |
| SOIC DW package compatibility | Standard 20-pin SOIC footprint supports drop-in replacement for SN74LS1244, SN74ALS244, and SN74ALS1240 in legacy layouts. |
Applications
| Memory Address Buffering | Parallel Bus Transceiver Interface |
|---|---|
|
Use Scenario: Driving 16-bit address bus between microprocessor (e.g., 80286) and multiple memory modules in industrial PLC backplanes. IC Role / Device Role / Timing Role: Noninverting octal buffer providing isolation and drive strength for A0–A15 lines; 1OE/2OE synchronized to memory select strobes. Use Value: Prevents address line skew and signal degradation across 10+ inch PCB traces while supporting 8-MHz bus clock rates. |
Use Scenario: Bidirectional data path conditioning between ISA bus peripherals and local FPGA-based I/O controllers. IC Role / Device Role / Timing Role: Dual 4-bit buffer acting as direction-controlled data latch - one group for D0–D3, second for D4–D7, with OE tied to DIR signal. Use Value: Eliminates need for discrete transceivers; enables clean 3-state handshaking with <13 ns enable latency and <14 ns propagation. |
| Legacy CPU Support Logic | Industrial Backplane Signal Conditioning |
|
Use Scenario: Interfacing Z80 or 68000 CPU address latches to peripheral decoders in retro-computing or test equipment designs. IC Role / Device Role / Timing Role: Noninverting buffer isolating latch outputs from decoder inputs; 3-state capability allows shared address decoding resources. Use Value: Maintains TTL logic thresholds across long trace runs and prevents latch output overload - critical for reliable decode timing. |
Use Scenario: Strengthening control signals (e.g., /IOR, /IOW, /MEMR) distributed across modular rack-mounted instrumentation chassis. IC Role / Device Role / Timing Role: Octal driver boosting weak microcontroller GPIO outputs to full TTL swing and current compliance for 10+ downstream receivers. Use Value: Ensures noise-immune signal integrity over 30-cm ribbon cables and eliminates false triggering in EMI-prone factory environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal noninverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS244N | Same ALS family, identical pinout and logic function, but in 20-pin PDIP (N) package - no RoHS or MSL-1 compliance. | Preferred for through-hole prototyping or repair of legacy DIP-based systems; lacks SOIC thermal and density advantages. | Select SN74ALS244N only when board layout mandates DIP footprint or RoHS exemption is required. |
| SN74LS1244DW | LS-family version - slower (tPLH ≤ 25 ns), higher ICC (≤25 mA), same 20-pin SOIC DW package and pinout. | Suitable for cost-sensitive, lower-speed systems where ALS speed/power benefits are unnecessary; broader temperature availability. | Choose SN74LS1244DW if design tolerates 80% longer propagation delay and prioritizes component cost over performance. |
Compared with SN74ALS1244ADW, SN74ALS244N offers identical electrical behavior but requires PCB redesign for DIP mounting, while SN74LS1244DW trades 45% slower timing and +47% higher supply current for wider legacy availability and simpler qualification.
Availability
SN74ALS1244ADW is available at Aetrix Electronics and suitable for industrial control backplanes, legacy CPU support circuits, and parallel bus interface designs requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS1244ADW 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 founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial and automotive reach.
The SN74ALS1244ADW belongs to TI's legacy 74ALS logic family, engineered for high-density, low-power memory addressing and bus driving in 1980s–1990s computing and industrial control systems.
FAQ
What is the maximum operating frequency supported by SN74ALS1244ADW?
The SN74ALS1244ADW does not specify a maximum clock frequency, but its propagation delay (tPLH/tPHL ≤ 14 ns) and 3-state timing (tPZH ≤ 13 ns) support reliable operation in 8-MHz bus systems with adequate setup/hold margins. System-level frequency depends on load capacitance, trace length, and driver strength - for 50-pF loads, it sustains clean edges up to 35 MHz small-signal bandwidth.
Can SN74ALS1244ADW be used as a direct replacement for SN74LS1244DW in an existing design?
Yes, SN74ALS1244ADW is pin-compatible and functionally equivalent to SN74LS1244DW, sharing identical 20-pin SOIC DW footprint and logic behavior. However, SN74ALS1244ADW delivers 45% faster propagation (14 ns vs. 25 ns) and draws ~30% less supply current (17 mA vs. 25 mA), improving timing margin and thermal performance without layout changes.
Does SN74ALS1244ADW support hot-plug or live insertion into a powered bus?
No, SN74ALS1244ADW is not designed for hot-plug operation. Its 3-state outputs do not feature bus-hold, power-up/down protection, or Ioff partial-power-down capability. Inserting or removing SN74ALS1244ADW while VCC or bus signals are active risks latch-up or output contention - always power down the system before handling.
What is the meaning of "pnp inputs" in SN74ALS1244ADW datasheet specifications?
The pnp input structure in SN74ALS1244ADW replaces conventional TTL npn input transistors with pnp devices, reducing input current to ≤0.1 mA per pin (vs. ~1.6 mA for standard LS). This cuts DC loading on upstream drivers, enabling >20-fanout on shared address lines and improving noise immunity in high-density bus environments.
Is SN74ALS1244ADW compliant with modern RoHS and REACH requirements?
Yes, SN74ALS1244ADW (including suffixes DWG4/DWRG4) is RoHS-compliant and classified as "Green (RoHS & no Sb/Br)" per TI's packaging documentation. It contains no lead, bromine, or antimony-based flame retardants, meets EU Directive 2011/65/EU, and carries MSL Level-1 moisture sensitivity rating for unlimited floor life at ≤30°C/60% RH.
SN74ALS1244ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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, 16mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74ALS1244ADW FAQ
1.How can I place an order for SN74ALS1244ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS1244ADW 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 SN74ALS1244ADW reliable?
The price and inventory of SN74ALS1244ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS1244ADW is usually 5 days.
3.What payment methods are accepted for SN74ALS1244ADW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS1244ADW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS1244ADW?
SN74ALS1244ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS1244ADW 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 SN74ALS1244ADW?
For technical support, including SN74ALS1244ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS1244ADW requirements.
6.How does Aetrix verify that SN74ALS1244ADW is sourced from the original manufacturer or authorized distributors?
All SN74ALS1244ADW 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 SN74ALS1244ADW meets industry standards.
7.What is the process for return or replacement of SN74ALS1244ADW?
All SN74ALS1244ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS1244ADW, 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 SN74ALS1244ADW part is unused and in its original packaging.
Return procedure for SN74ALS1244ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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