Texas Instruments SN74HCT244NG4

Overview

SN74HCT244NG4 from Texas Instruments is an octal non-inverting 3-state buffer/line driver IC designed for bus-oriented memory address and clock signal conditioning. It operates at 4.5–5.5 V, delivers ±6 mA output drive per channel, exhibits 13 ns typical propagation delay (tpd) at 5.5 V with 50 pF load, and supports TTL-compatible inputs. It is used in server backplanes to isolate and strengthen memory address lines between CPU and DRAM modules.

For engineers reviewing the SN74HCT244NG4 datasheet, SN74HCT244NG4 pinout, SN74HCT244NG4 application, or SN74HCT244NG4 equivalent, key selection criteria include 3-state bus contention control, LSTTL-load driving capability (up to 15 loads), low quiescent current (≤80 µA), input voltage compatibility with legacy TTL logic, and thermal performance in SOIC-20 packaging.

Technical Context

The SN74HCT244NG4 integrates two independent 4-bit buffer sections, each with dedicated active-low output-enable (OE) control. Its CMOS HCT process ensures TTL-level input thresholds (VIH = 2 V min, VIL = 0.8 V max) while delivering rail-to-rail CMOS output swing and high-current sourcing/sinking (±6 mA at 5 V).

Each buffer passes data non-inverted from A-inputs to Y-outputs when OE is low; outputs enter high-impedance state when OE is high. This architecture enables bidirectional bus isolation, memory address latching, and clock fanout without loading source drivers - critical in dense PCB layouts with long trace runs.

Key Specifications

Pinout & Package

SN74HCT244NG4 is supplied in a 20-pin PDIP (Plastic Dual In-line Package) with 0.300-inch body width and 0.100-inch lead pitch. The package is through-hole mountable, RoHS-compliant, and rated for –40°C to +85°C operating temperature.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT244N, SN74HCT244NG4 provides identical performance with RoHS-compliant finish, while SN74AHCT244N trades higher static current for faster switching and broader supply flexibility - making it suitable only when those specific advantages are needed.

Availability

SN74HCT244NG4 is available at Aetrix Electronics and suitable for server backplanes, industrial LED displays, network switch control planes, and motor driver interface logic requiring stable component supply across extended product lifecycles.

Supply support for SN74HCT244NG4 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 innovation in industrial, automotive, and communications markets.

The SN74HCT244NG4 belongs to TI's 74HCT logic family, engineered for TTL-compatible interfacing in industrial control, computing infrastructure, and legacy-system upgrades where reliability, noise immunity, and 5 V compatibility are essential.

FAQ

What is the operating temperature range for SN74HCT244NG4?

The SN74HCT244NG4 is rated for operation from –40°C to +85°C. This industrial-grade temperature range ensures reliable performance in server chassis, factory automation panels, and outdoor telecom equipment where ambient temperatures fluctuate significantly. All electrical specifications in the datasheet - including propagation delay, output drive, and input thresholds - are guaranteed across this full range.

Does SN74HCT244NG4 support mixed-voltage interfacing?

SN74HCT244NG4 accepts TTL-compatible input voltages (VIH ≥ 2 V, VIL ≤ 0.8 V) across its 4.5–5.5 V supply range, allowing direct connection to 3.3 V logic outputs when VCC = 5 V - provided the 3.3 V device can source sufficient current to meet the 2 V VIH threshold. However, it does not support true 3.3 V supply operation; for dual-supply systems, consider SN74AHCT244NG4 instead.

How should unused inputs be handled on SN74HCT244NG4?

All unused inputs on SN74HCT244NG4 - including A-inputs and OE pins - must be tied to either VCC or GND. Floating inputs cause increased ICC, erratic output behavior, and potential latch-up. For OE pins, tie to VCC (via pull-up) to ensure outputs remain in high-impedance state during power-up; for unused A inputs, tie to GND to minimize leakage-induced noise coupling.

What is the maximum capacitive load SN74HCT244NG4 can drive reliably?

SN74HCT244NG4 is characterized for loads up to 150 pF, with tpd increasing from 13 ns (50 pF) to 18 ns (150 pF) at 5.5 V. Driving >150 pF risks violating setup/hold timing in synchronous systems and may cause ringing due to impedance mismatch. For heavier loads, add series termination resistors or use a dedicated buffer amplifier stage upstream of SN74HCT244NG4.

Is SN74HCT244NG4 pin-compatible with older SN74LS244 devices?

SN74HCT244NG4 shares identical pinout and logic function with SN74LS244, but differs electrically: it draws far less supply current (80 µA vs ~30 mA), has CMOS-compatible outputs (rail-to-rail swing), and requires no external pull-ups on OE. While drop-in replacement is mechanically possible, verify timing margins and bus loading - especially in legacy LS designs where propagation delay and fanout assumptions differ significantly.