Texas Instruments SN74LS244DWE4

Overview

SN74LS244DWE4 from Texas Instruments is an octal non-inverting 3-state buffer/line driver in SOIC-20 package, designed for memory address and bus line driving with 24 mA sink current capability, 18 ns typical propagation delay at 5 V, and hysteresis-enhanced noise immunity. It serves as a bidirectional bus interface component in legacy industrial control and telecom backplane systems.

For engineers reviewing the SN74LS244DWE4 datasheet, SN74LS244DWE4 pinout, SN74LS244DWE4 application, or SN74LS244DWE4 equivalent, key selection criteria include 3-state output control timing (tPZH/tPLZ), input hysteresis (0.4 V), PNP-input DC loading reduction, compatibility with 3.3-V/5-V mixed logic, and SOIC-20 thermal performance (RθJA = 90.3°C/W).

Technical Context

The SN74LS244DWE4 implements two independent 4-bit non-inverting buffer sections, each with active-low output-enable (1G, 2G) controlling high-impedance state. Its PNP input structure reduces DC loading on driven buses, while built-in input hysteresis (0.2–0.4 V) improves noise margins in electrically noisy environments.

It operates strictly within 4.75–5.25 V supply range and supports TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max). Output drive strength is asymmetric: 24 mA sink (IOL) at VOL ≤ 0.5 V, but only 3 mA source (IOH) at VOH ≥ 2.4 V - a characteristic of LS-family totem-pole outputs.

Key Specifications

Pinout & Package

SN74LS244DWE4 uses a 20-pin SOIC (DW) package measuring 12.80 mm × 7.50 mm, with standard 0.050″ (1.27 mm) lead pitch and gull-wing surface-mount leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state buffer applications.

Compared with SN74LS240DWE4, SN74LS244DWE4 provides non-inverting signal path essential for address/data integrity; versus SN74HC244N, it delivers superior noise immunity and higher drive in legacy 5-V infrastructure - making it irreplaceable in electromagnetically harsh settings.

Availability

SN74LS244DWE4 is available at Aetrix Electronics and suitable for industrial control systems, telecom infrastructure upgrades, and legacy embedded design refreshes requiring stable component supply and long-term obsolescence management.

Supply support for SN74LS244DWE4 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 50 years of industrial-grade product heritage.

SN74LS244DWE4 belongs to TI's legacy LS (Low-Power Schottky) logic family, engineered for robust bus interfacing in mission-critical 5-V systems where noise immunity, predictable timing, and proven reliability outweigh ultra-low power requirements.

FAQ

What is the recommended operating voltage range for SN74LS244DWE4?

The SN74LS244DWE4 requires a supply voltage between 4.75 V and 5.25 V for guaranteed operation per TI's datasheet. Operation below 4.75 V may cause marginal VOH levels or increased propagation delay; above 5.25 V risks exceeding absolute maximum ratings and potential device damage. Always use local 0.1 µF ceramic decoupling at the VCC pin of SN74LS244DWE4.

Does SN74LS244DWE4 support 3.3-V logic inputs?

Yes, SN74LS244DWE4 accepts 3.3-V logic inputs reliably due to its 2-V minimum VIH specification and PNP input structure. This allows direct connection to 3.3-V microcontrollers or FPGAs in mixed-voltage systems without level-shifting circuitry - a key advantage confirmed in TI's "Inputs Tolerant Down to 2 V" feature listing.

What is the maximum output sink current per pin on SN74LS244DWE4?

SN74LS244DWE4 supports up to 24 mA sink current per output pin (IOL) while maintaining VOL ≤ 0.5 V at VCC = 4.75 V. This rating applies under recommended operating conditions and is validated across temperature; exceeding it risks output voltage degradation or thermal stress. Total device ICC remains within safe limits if fewer than four outputs drive full load simultaneously.

How does the hysteresis feature benefit SN74LS244DWE4 in real-world applications?

The 0.2–0.4 V input hysteresis in SN74LS244DWE4 widens the valid logic transition region, effectively filtering out sub-threshold noise spikes on shared bus lines. In applications like telecom backplanes or industrial motor control cabinets, this prevents false triggering caused by EMI or crosstalk - a documented design value confirmed in TI's Feature Description section.

Is SN74LS244DWE4 pin-compatible with SN74LS240DWE4?

Yes, SN74LS244DWE4 and SN74LS240DWE4 share identical SOIC-20 pinouts, package dimensions, and electrical timing specifications. The sole functional difference is output polarity: SN74LS244DWE4 is non-inverting (A→Y), while SN74LS240DWE4 is inverting (A→¬Y). No PCB layout change is required when substituting between them for polarity-matched designs.