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Texas Instruments SN74ALS244C-1N
- Part No.:
- SN74ALS244C-1N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ALS244C-1N.pdf
- Description:
- IC BUF NON-INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:980
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Product details
Overview
SN74ALS244C-1N from Texas Instruments is an octal non-inverting 3-state buffer/line driver in a 20-pin plastic DIP (PDIP) package, designed for memory address and bus line driving. It operates from 4.5 V to 5.5 V, supports 0°C to 70°C ambient, delivers 48 mA low-level output current (IOL), and features pnp inputs to reduce DC loading on TTL-compatible systems.
For engineers reviewing the SN74ALS244C-1N datasheet, SN74ALS244C-1N pinout, SN74ALS244C-1N application, or SN74ALS244C-1N equivalent, this page provides verified functional specifications, validated pin assignments, real-world use cases in legacy bus interfacing, and confirmed drop-in alternatives for industrial control and retro-computing designs.
Technical Context
The SN74ALS244C-1N implements two independent 4-bit groups (1A–1Y and 2A–2Y), each controlled by its own active-low 3-state enable input (1OE, 2OE). Its ALS (Advanced Low-Power Schottky) logic family ensures compatibility with standard TTL while reducing power consumption versus original LS devices.
Propagation delays are tightly specified: tPLH/tPHL ≤ 10 ns (A→Y), tPZH/tPZL ≤ 20 ns (OE→Y), enabling reliable operation in high-speed address latching and bidirectional data bus isolation at up to ~50 MHz system clock edges under CL = 50 pF load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS (Advanced Low-Power Schottky) - ensures TTL compatibility with lower ICC than LS, critical for dense board layouts. |
| Supply Voltage | 4.5 V to 5.5 V - matches standard +5 V rail with ±10% tolerance; not rated for 3.3 V operation. |
| Output Drive | IOL = 48 mA (max) - enables direct drive of multiple TTL loads or termination-resistor networks without external buffers. |
| Operating Temp | 0°C to 70°C - commercial-grade rating; suitable for office equipment, industrial controllers, and embedded instrumentation. |
| Propagation Delay | tPLH/tPHL ≤ 10 ns - supports address/data setup/hold timing in 8086/8088-based systems and ISA-bus peripherals. |
| 3-State Enable | Active-low OE per group - allows independent control of two 4-bit channels for multiplexed bus arbitration. |
| Input Structure | pnp input stage - reduces input current (IIL = –0.1 mA max), minimizing loading on upstream drivers like microprocessor address pins. |
Pinout & Package
SN74ALS244C-1N uses a 20-pin PDIP (Plastic Dual In-line Package) with 300-mil body width and standard through-hole footprint. Pin 1 is located at the left end of the top row (notch-up orientation).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low 3-state enable inputs - assert low to enable corresponding 4-bit buffer group; high places outputs in high-impedance state. |
| 2–5, 18–15 | 1A1–1A4, 2A1–2A4 | Buffer inputs - accept TTL-level signals; pnp input structure minimizes DC loading on source drivers. |
| 6–9, 14–11 | 1Y1–1Y4, 2Y1–2Y4 | Non-inverting 3-state outputs - drive bus lines or memory address registers; capable of sinking 48 mA per pin. |
| 10 | GND | Ground reference - must be connected to system common; decoupling capacitor recommended near VCC pin. |
| 20 | VCC | +5 V supply - requires local 0.1 µF ceramic bypass capacitor between VCC and GND for noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Octal non-inverting buffer with dual 3-state control | Enables independent gating of two 4-bit data/address paths on a single IC - reduces component count vs discrete buffers. |
| 48 mA low-level output sink capability | Drives up to 20 standard TTL loads per output - eliminates need for external bus drivers in legacy backplane designs. |
| pnp input structure | Reduces input current to –0.1 mA max - preserves fan-out margin when driven by older microprocessors (e.g., Z80, 8085). |
| ALS logic family | Delivers 2× speed vs LS at comparable power - achieves 10 ns propagation delay with ICC < 25 mA (outputs low). |
| Standard PDIP-20 package | Compatible with through-hole assembly, socketing, and legacy PCB tooling - supports repairability and prototyping. |
Applications
| ISA Bus Address Latch Interface | Industrial PLC I/O Expansion Module |
|---|---|
Use Scenario: Interfacing an 80286 CPU's 20-bit address bus to ISA-compatible peripheral cards requiring isolated, buffered address lines. IC Role / Device Role / Timing Role: Non-inverting 3-state buffer that isolates and drives A0–A19 address lines during memory-mapped I/O cycles, enabled only when specific I/O address range is decoded. Use Value: 48 mA sink capability ensures robust signal integrity across long ISA backplane traces; dual OE pins allow precise timing control synchronized to ISA IOR/IOW strobes. | Use Scenario: Adding parallel digital input capability to a modular PLC base unit via a DIN-rail-mounted expansion module with opto-isolated inputs. IC Role / Device Role / Timing Role: Buffering and level-shifting 8-channel optocoupler outputs to the PLC's internal 5 V logic bus, with 3-state control enabling shared bus access among multiple modules. Use Value: pnp inputs minimize loading on optocoupler collector outputs; ALS speed ensures sub-100 ns response to fast field-edge transitions in factory automation. |
| Retrocomputing Memory Expansion Board | Legacy Test Equipment Data Acquisition Interface |
Use Scenario: Building a RAM expansion card for a vintage Apple IIe or IBM PC XT with bank-switched 64 KB memory banks. IC Role / Device Role / Timing Role: Driving upper address bits (A14–A19) to SRAM chips while isolating them from the CPU bus during refresh or DMA cycles using 3-state control. Use Value: 10 ns propagation delay meets tight 8088/6502 timing budgets; PDIP-20 package allows hand-soldering and socket replacement in hobbyist builds. | Use Scenario: Connecting 8-bit parallel data outputs from analog-to-digital converters in aging benchtop oscilloscopes or spectrum analyzers to microcontroller-based front-end processors. IC Role / Device Role / Timing Role: Isolating ADC output latches from shared system data bus, preventing contention during simultaneous read/write operations across multiple instrument subsystems. Use Value: Dual OE control permits time-multiplexed access to multiple ADC channels; 48 mA drive supports direct connection to microcontroller GPIO pins without series resistors. |
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 |
|---|---|---|---|
| SN74ALS244CN | No -1 suffix; rated for IOL = 24 mA (not 48 mA) - lower drive strength, higher VOL at full load. | Suitable for lighter bus loads where 24 mA suffices; not recommended for long traces or >10 TTL loads. | Select SN74ALS244CN only if drive requirement is ≤24 mA and cost sensitivity outweighs performance margin. |
| SN74AS244AN | AS family: faster (tPLH/tPHL ≤ 6.2 ns), higher IOL = 64 mA, but higher ICC (up to 90 mA) and stricter VIH/VIL thresholds. | Better for high-speed timing-critical paths; requires tighter VCC regulation and more aggressive decoupling. | Choose SN74AS244AN when propagation delay < 7 ns is mandatory and power budget allows ≥2× ICC increase. |
Compared with SN74ALS244CN and SN74AS244AN, the SN74ALS244C-1N uniquely balances 48 mA drive, 10 ns speed, and ALS power efficiency - making it optimal for mid-speed industrial bus interfaces where reliability and thermal margin are prioritized over peak speed.
Availability
SN74ALS244C-1N is available at Aetrix Electronics and suitable for industrial control systems, retrocomputing hardware restoration, and legacy test equipment repair requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS244C-1N 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 solutions for industrial, automotive, and communications markets.
The SN74ALS244C-1N belongs to TI's legacy TTL logic portfolio, engineered for backward compatibility with 1980s-era microprocessor systems while delivering improved power-speed trade-offs over original 74LS devices.
FAQ
What is the maximum output sink current specification for SN74ALS244C-1N?
The SN74ALS244C-1N is rated for a maximum low-level output current (IOL) of 48 mA per output pin when VCC is between 4.75 V and 5.25 V. This value is explicitly defined for the "-1" version in the SDAS142C datasheet and distinguishes it from the standard SN74ALS244CN, which specifies only 24 mA. Exceeding 48 mA risks violating absolute maximum ratings and may cause output voltage degradation or thermal stress.
Can SN74ALS244C-1N operate reliably at 3.3 V supply voltage?
No, SN74ALS244C-1N is not specified for 3.3 V operation. Its recommended operating supply voltage is strictly 4.5 V to 5.5 V, and absolute maximum VCC is 7 V. Applying 3.3 V will result in undefined logic levels, excessive propagation delay, and potential failure to meet VIH (2.0 V min) or VOL (0.4 V max) specifications. For 3.3 V systems, consider modern 74LVC or 74ALVC series buffers instead.
How does the pnp input structure of SN74ALS244C-1N benefit system design?
SN74ALS244C-1N uses pnp-based input circuitry to reduce input current draw: IIL is rated at –0.1 mA max (vs –0.4 mA for standard LS). This lowers DC loading on upstream drivers - especially beneficial when interfacing with older microprocessors (e.g., Z80, 8085) or TTL-compatible address latches with limited fan-out. It preserves timing margins and reduces cumulative voltage drop across long daisy-chained buses.
Is SN74ALS244C-1N pin-compatible with SN74ALS244CN?
Yes, SN74ALS244C-1N and SN74ALS244CN share identical pinout, package (PDIP-20), and functional block diagram. Both have dual 4-bit groups with separate 1OE/2OE controls and identical pin assignments (e.g., Pin 1 = 1OE, Pin 2–5 = 1A1–1A4, etc.). The only electrical difference is the higher IOL rating (48 mA vs 24 mA) in the -1N variant - no PCB layout changes are required for substitution.
What is the typical propagation delay from input to output for SN74ALS244C-1N?
The typical propagation delay (tPLH and tPHL) for SN74ALS244C-1N is 2 ns at VCC = 5 V and TA = 25°C, with a maximum of 10 ns across the full 0°C to 70°C operating range under CL = 50 pF and R1/R2 = 500 Ω load conditions. This delay applies to both rising and falling edges of the A→Y path and is measured at 1.3 V threshold points per JEDEC standards.
SN74ALS244C-1N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- 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, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74ALS244C-1N FAQ
1.How can I place an order for SN74ALS244C-1N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS244C-1N 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 SN74ALS244C-1N reliable?
The price and inventory of SN74ALS244C-1N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS244C-1N is usually 5 days.
3.What payment methods are accepted for SN74ALS244C-1N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS244C-1N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS244C-1N?
SN74ALS244C-1N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS244C-1N 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 SN74ALS244C-1N?
For technical support, including SN74ALS244C-1N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS244C-1N requirements.
6.How does Aetrix verify that SN74ALS244C-1N is sourced from the original manufacturer or authorized distributors?
All SN74ALS244C-1N 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 SN74ALS244C-1N meets industry standards.
7.What is the process for return or replacement of SN74ALS244C-1N?
All SN74ALS244C-1N units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS244C-1N, 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 SN74ALS244C-1N part is unused and in its original packaging.
Return procedure for SN74ALS244C-1N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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