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Texas Instruments SN74LS244N
- Part No.:
- SN74LS244N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74LS244N.pdf
- Description:
- IC BUF NON-INVERT 5.25V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,245
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Product details
Overview
SN74LS244N from Texas Instruments is an octal non-inverting 3-state buffer/line driver in a 20-pin PDIP package, designed for memory address and bus line driving. It features dual 4-bit channels with independent active-low output-enable (1G, 2G), 24 mA sink capability per output, 18 ns typical propagation delay at 5 V, and hysteresis-enhanced noise immunity-used in legacy industrial control backplanes and LED display column drivers.
For engineers reviewing the SN74LS244N datasheet, SN74LS244N pinout, SN74LS244N application, or SN74LS244N equivalent, this page delivers verified electrical specs, functional pin mapping, real-world use cases in bus isolation and level restoration, and two validated alternative parts with documented differences in drive strength and timing.
Technical Context
The SN74LS244N implements two independent 4-bit non-inverting buffer sections, each controlled by its own active-low output-enable input (1G on Pin 1, 2G on Pin 19). Its PNP-input structure reduces DC loading on upstream logic, while built-in input hysteresis provides 400 mV noise margin-critical for noisy industrial bus environments.
All eight outputs are 3-state capable and share common VCC (Pin 20) and GND (Pin 10) rails. The device operates strictly at 5 V (4.75–5.25 V recommended), supports TTL-level inputs down to 0.7 V (VIL), and drives terminated lines as low as 133 Ω without signal degradation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75–5.25 V - ensures compatibility with standard TTL power rails and stable operation under ±5% regulation tolerance |
| Output Sink Current | 24 mA per Y output - sufficient to directly drive multiple TTL loads or LED segments without external buffering |
| Propagation Delay | 12–18 ns (tPLH/tPHL) - enables reliable operation in 20–25 MHz bus systems with margin for trace delays |
| Input Hysteresis | 0.2–0.4 V - improves noise rejection on shared bus lines subject to EMI or ground bounce |
| Off-State Leakage | ±20 µA (IOZL/IOZH) - maintains high-impedance integrity during bus arbitration or hot-swap conditions |
| DC Input Tolerance | Valid down to 2 V - allows interoperability with 3.3-V logic families when used as a level translator |
Pinout & Package
SN74LS244N uses a 20-pin Plastic Dual In-line Package (PDIP-N) with 24.33 mm × 6.35 mm body size and 2.54 mm lead pitch. Leads are tin-lead plated, RoHS-compliant per TI's 2016 revision.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (1G) | Channel 1 output enable | Active-low control: pulls all Channel 1 Y outputs (1Y1–1Y4) into high-Z when HIGH; enables pass-through when LOW |
| 2, 4, 6, 8 (1A1–1A4) | Channel 1 data inputs | Non-inverting inputs feeding corresponding 1Y outputs; PNP structure minimizes loading on source bus |
| 12, 14, 16, 18 (1Y1–1Y4) | Channel 1 buffered outputs | 3-state totem-pole outputs; sink up to 24 mA, source limited to 3 mA (VOH = 2.4 V @ –3 mA) |
| 11, 13, 15, 17 (2A1–2A4) | Channel 2 data inputs | Independent 4-bit input group mirroring Channel 1; electrically isolated but sharing VCC/GND |
| 3, 5, 7, 9 (2Y4–2Y1) | Channel 2 buffered outputs | Non-inverting outputs paired with 2A inputs; pin order reversed vs. 1Y for PCB routing flexibility |
| 19 (2G) | Channel 2 output enable | Active-low control identical in function to 1G but scoped to Channel 2 only |
| 10 (GND) | Ground reference | Primary return path for all I/O and supply currents; requires low-inductance connection to system ground plane |
| 20 (VCC) | Power supply | 5-V supply rail; decoupling capacitor (0.1 µF ceramic) required within 10 mm of this pin |
Key Features
| Feature | Design Value |
|---|---|
| Independent dual-channel control | Separate 1G and 2G pins allow asymmetric bus partitioning-e.g., enable Channel 1 for address latching while holding Channel 2 in high-Z for data readback |
| Hysteresis-enhanced inputs | 0.4 V typical hysteresis width raises effective noise margin above standard TTL, reducing false triggering on long PCB traces |
| PNP input structure | Reduces input current draw to ≤0.2 mA (IIL), lowering loading on microcontroller GPIOs or PROM outputs driving address buses |
| Bus-compatible 3-state outputs | Outputs fully comply with IEEE 1149.1 boundary-scan high-Z requirements and support wired-OR configurations |
| Terminated-line drive capability | Validated to drive 133 Ω parallel-terminated lines-enables direct interface to legacy backplane standards like STD Bus or Multibus I |
Applications
| Memory Address Buffering | LED Display Column Driver |
|---|---|
Use Scenario: Driving 16-bit address bus from microprocessor to multiple ROM/RAM chips in an 8080/8085-based industrial controller. IC Role / Device Role / Timing Role: Non-inverting buffer isolating CPU address lines from capacitive load of multiple memory devices; 18 ns tPHL ensures setup time compliance with 4 MHz clock cycles. Use Value: Prevents address skew and decoding errors caused by fan-out-induced delay variation across 16 lines. | Use Scenario: Sourcing current to 8-column segments of a 16×8 LED matrix in a factory HMI panel. IC Role / Device Role / Timing Role: High-current sink driver (24 mA per channel) enabling bright, uniform LED illumination without external transistors. Use Value: Eliminates need for discrete NPN arrays, reducing BOM count and PCB area by 40% versus discrete solutions. |
| Backplane Bus Isolation | Legacy System Level Restoration |
Use Scenario: Isolating CPU data bus from peripheral expansion slots in a ruggedized telecom shelf controller. IC Role / Device Role / Timing Role: Bidirectional bus buffer using separate 1G/2G enables; prevents contention during DMA transfers by sequencing enable signals. Use Value: Enables hot-plug capability for add-on cards without risking bus lockup or latch-up on main controller. | Use Scenario: Restoring degraded TTL signal edges on a 2-meter ribbon cable between PLC CPU and I/O module. IC Role / Device Role / Timing Role: Repeater restoring rise/fall times degraded by cable capacitance; hysteresis rejects noise induced along cable run. Use Value: Recovers marginal signals that would otherwise cause CRC errors or missed interrupts in deterministic control loops. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal non-inverting 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS240N | Inverting outputs (A→¬Y); identical pinout, timing, and drive specs | Requires logic inversion in upstream design; unsuitable where signal polarity must be preserved | Select when bus protocol mandates inverted control signals (e.g., active-low chip selects) |
| SN74HC244N | CMOS technology: 2 µA ICC vs. 46 mA typical for SN74LS244N; 7 ns max tPD; 2–6 V VCC range | Not drop-in: higher VOH/VOL thresholds, lower noise immunity, no hysteresis; incompatible with legacy 5-V TTL bus loading | Choose for new low-power designs with clean 3.3-V supplies; avoid in mixed-voltage or noisy industrial settings |
Compared with SN74LS240N, SN74LS244N preserves signal polarity critical for address/data integrity; compared with SN74HC244N, it delivers proven noise robustness and bus-drive strength essential in legacy industrial backplanes-making it irreplaceable where signal fidelity trumps power savings.
Availability
SN74LS244N is available at Aetrix Electronics and suitable for memory address buffering, LED display driving, backplane bus isolation, and legacy system level restoration requiring stable component supply across extended product lifecycles.
Supply support for SN74LS244N 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 for industrial, automotive, and communications markets.
The SN74LS244N belongs to TI's legacy LS-TTL logic family, engineered for high-noise-margin bus interfacing in industrial control, test equipment, and military-grade systems where reliability outweighs power efficiency.
FAQ
What is the maximum operating temperature range for the SN74LS244N?
The SN74LS244N is rated for commercial operation from 0°C to +70°C ambient temperature. This range is defined in TI's SDLS144D datasheet Section 6.3 and applies specifically to the SN74LS244N in PDIP (N) packaging. Operation outside this range may result in parametric shift or failure; thermal derating is not specified for this part.
Can the SN74LS244N drive a 50-Ω transmission line?
No, the SN74LS244N is not characterized to drive 50-Ω lines. TI's datasheet explicitly states it can drive terminated lines "down to 133 Ω" (Section 3, Description). Attempting 50-Ω termination would exceed output current limits and degrade waveform integrity-use SN74S244 or dedicated line drivers for such applications.
Is the SN74LS244N pin-compatible with the SN74LS244D (SOIC) package?
Yes, the SN74LS244N (PDIP) and SN74LS244D (SOIC) share identical pin functions and numbering per TI's Pin Configuration and Functions table (Page 3 of SDLS144D). However, physical layout differs: N-package has 2.54 mm lead pitch and through-hole mounting, while D-package uses 1.27 mm pitch and surface-mount pads-PCB footprint is not interchangeable.
Does the SN74LS244N support hot insertion into a live bus?
No, the SN74LS244N lacks hot-swap protection circuitry. Its inputs are not guaranteed fault-tolerant during live insertion, and powering VCC before GND-or applying input signals before VCC stabilization-may cause latch-up or parametric shift. Always sequence power and assert 1G/2G HIGH before enabling signals.
What is the purpose of the hysteresis on SN74LS244N inputs?
The hysteresis (0.2–0.4 V typical) on SN74LS244N inputs widens the voltage threshold window between logic HIGH and LOW transitions. This prevents oscillation or metastability when input signals cross the switching point slowly-common on long PCB traces or unterminated cables-and improves noise immunity in electrically noisy industrial environments.
SN74LS244N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74LS244N FAQ
1.How can I place an order for SN74LS244N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS244N 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 SN74LS244N reliable?
The price and inventory of SN74LS244N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS244N is usually 5 days.
3.What payment methods are accepted for SN74LS244N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS244N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS244N?
SN74LS244N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS244N 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 SN74LS244N?
For technical support, including SN74LS244N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS244N requirements.
6.How does Aetrix verify that SN74LS244N is sourced from the original manufacturer or authorized distributors?
All SN74LS244N 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 SN74LS244N meets industry standards.
7.What is the process for return or replacement of SN74LS244N?
All SN74LS244N units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS244N, 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 SN74LS244N part is unused and in its original packaging.
Return procedure for SN74LS244N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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