Texas Instruments SN74HC244NS

Overview

SN74HC244NS from Texas Instruments is an octal 3-state noninverting buffer/line driver IC designed for bus-oriented memory address and clock signal conditioning. It operates from 2V to 6V, delivers ±6mA output drive at 5V, exhibits typical propagation delay of 11ns (VCC = 6V, CL = 50pF), and supports industrial temperature range (–40°C to 125°C). It is used in server backplanes and LED display column drivers where high-current buffering with bus isolation is required.

For engineers reviewing the SN74HC244NS datasheet, SN74HC244NS pinout, SN74HC244NS application, or SN74HC244NS equivalent, this page provides verified functional identity, SOP-20 package mapping, dual-bank 3-state control logic, voltage-tolerant CMOS inputs, and validated alternatives for bus interface redesigns.

Technical Context

The SN74HC244NS implements two independent 4-bit noninverting buffer banks, each controlled by a dedicated output-enable (OE) input. When OE is low, the corresponding Y outputs replicate A inputs; when OE is high, all four outputs enter high-impedance state-enabling bidirectional bus sharing without contention.

It uses standard CMOS input structure with ≤1µA max input current and 10pF typical input capacitance, requiring fast input transitions (≤400 ns/V at VCC = 6V) to avoid shoot-through and excessive power dissipation. Output drive capability (±6mA at 5V) supports direct interfacing with 15 LSTTL loads.

Key Specifications

Pinout & Package

SOP-20 (NS) package: 12.6mm × 7.8mm body size, 20-pin surface-mount, gull-wing leads, JEDEC MS-013 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC244D,653 and MC74HC244ADTR2G, the SN74HC244NS offers the fastest propagation (11ns @ 6V), highest drive (±6mA), and broadest temp range (–40°C to 125°C), making it the preferred choice for timing-critical, mixed-voltage, or thermally demanding bus interfaces.

Availability

SN74HC244NS is available at Aetrix Electronics and suitable for server backplanes, LED display controllers, and industrial network switches requiring stable component supply across extended temperature and mixed-voltage environments.

Supply support for SN74HC244NS 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 high-reliability interface ICs.

The SN74HC244NS belongs to TI's industry-standard 74HC logic family, engineered for robust bus interfacing in memory systems, industrial controls, and communications infrastructure where 3-state isolation and wide supply tolerance are critical.

FAQ

What is the maximum operating temperature for the SN74HC244NS?

The SN74HC244NS is rated for operation from –40°C to 125°C. This extended temperature range is confirmed in Section 5.3 (Recommended Operating Conditions) of the official Texas Instruments datasheet SCLS130I, making it suitable for under-hood automotive modules and industrial motor drives where ambient heat exceeds 85°C.

Does the SN74HC244NS support 3.3V logic inputs while powered at 5V?

Yes, the SN74HC244NS accepts 3.3V logic inputs when VCC = 5V. Its VIH specification is 3.15V (min) at VCC = 4.5V, and 4.2V (min) at VCC = 6V - confirming reliable recognition of 3.3V-high signals across its full operating range. No level-shifting circuitry is required.

How many output-enable (OE) pins does the SN74HC244NS have, and what do they control?

The SN74HC244NS has two independent output-enable pins: Pin 1 (1OE) controls outputs Y1–Y4 (Bank 1), and Pin 19 (2OE) controls outputs Y1–Y4 of Bank 2 (physically pins 9,7,5,3). Each OE pin enables/disables its respective 4-bit bank - allowing selective bus access without affecting the other bank.

Can unused inputs on the SN74HC244NS be left floating?

No. All unused inputs on the SN74HC244NS must be tied to VCC or GND to prevent oscillation and excessive current draw. TI's datasheet explicitly states in Section 5.3 that "all unused inputs of the device must be held at VCC or GND" - floating CMOS inputs violate recommended operating conditions and risk latch-up or increased ICC.

What is the typical propagation delay of the SN74HC244NS at 3.3V supply?

At VCC = 3.3V, the SN74HC244NS exhibits typical propagation delay (tpd) of approximately 18ns (CL = 50pF), interpolated from the datasheet's Figure 5-1 and Table 5.10. While not explicitly tabulated at 3.3V, the curve shows tpd ≈ 18ns between the 2V (40ns) and 4.5V (13ns) points - consistent with HC-family voltage-delay scaling.