Texas Instruments SN74HC244AN

Overview

SN74HC244AN from Texas Instruments is an octal noninverting buffer/line driver with 3-state outputs, organized as two independent 4-bit banks. It operates from 2V to 6V, delivers ±6mA output drive at 5V, exhibits typical propagation delay of 11ns (VCC = 6V, CL = 50pF), and supports bus-oriented memory address driving and I/O expansion in industrial control systems.

For engineers reviewing the SN74HC244AN datasheet, SN74HC244AN pinout, SN74HC244AN application, or SN74HC244AN equivalent, key selection criteria include its dual-bank 3-state enable architecture, wide supply range, high-current CMOS output capability, and compatibility with LSTTL load interfacing in memory and peripheral bus designs.

Technical Context

The SN74HC244AN implements two separate 4-bit noninverting buffer banks, each controlled by its own active-low output-enable input (1OE, 2OE). Each bank passes A-inputs to Y-outputs when its OE is low; outputs enter high-impedance state when OE is high - enabling bidirectional bus sharing without contention.

It uses standard CMOS inputs with ≤10pF input capacitance and ≤1µA max input current, requiring fast input transitions (≤400 ns/V at VCC = 6V) to avoid oscillation. Output drive strength (±6mA at 5V) and low ICC (80µA max) support dense, low-power bus buffering in mixed-voltage systems.

Key Specifications

Pinout & Package

SN74HC244AN is supplied in a 20-pin plastic dual in-line package (PDIP, N package), measuring 24.33mm × 9.4mm overall with a body size of 24.33mm × 6.35mm. The package is through-hole mountable and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT244N and 74LCX244M, the SN74HC244AN offers the broadest supply flexibility (2V–6V) and proven robustness in industrial temperature ranges (–40°C to 125°C), making it the preferred choice for general-purpose bus buffering where voltage domain agility and reliability outweigh marginal speed gains.

Availability

SN74HC244AN is available at Aetrix Electronics and suitable for industrial control systems, LED display subsystems, and network infrastructure equipment requiring stable component supply and long-term manufacturability.

Supply support for SN74HC244AN 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 delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The SN74HC244AN belongs to TI's industry-standard 74HC logic family, designed specifically for high-density, low-power bus interfacing in memory systems, I/O expansion, and peripheral control applications.

FAQ

What is the operating temperature range for the SN74HC244AN?

The SN74HC244AN is rated for operation from –40°C to +125°C. This extended industrial temperature range ensures reliable performance in demanding environments such as factory automation controllers, outdoor telecom equipment, and motor drive interfaces where ambient temperatures exceed commercial-grade limits. The SN74HC244AN maintains full electrical specifications across this range, including output drive and propagation delay stability.

Does the SN74HC244AN support 3.3V logic levels?

Yes, the SN74HC244AN fully supports 3.3V operation: its recommended supply range (2V–6V) includes 3.3V, and its CMOS inputs recognize VIH ≥ 2.0V and VIL ≤ 0.8V at VCC = 3.3V - compatible with standard 3.3V LVTTL and LVCMOS outputs. At 3.3V, it delivers ±4mA output drive and maintains typical tpd of ~15ns (CL = 50pF), making SN74HC244AN suitable for mixed-voltage board designs.

How should unused inputs be handled on the SN74HC244AN?

All unused inputs on the SN74HC244AN must be tied to either VCC or GND - never left floating. Floating CMOS inputs cause excessive current draw, potential oscillation, and increased EMI. For example, if Bank 2 is unused, tie 2OE to VCC (to disable outputs) and connect 2A1–2A4 to GND or VCC depending on required default state. TI recommends 10kΩ pull-up/down resistors where dynamic control is needed, as specified in the "Implications of Slow or Floating CMOS Inputs" application note.

Can the SN74HC244AN drive LEDs directly?

Yes, the SN74HC244AN can drive LEDs directly in low-current configurations: each output sources or sinks up to ±6mA at 5V, sufficient for indicator LEDs (typically 2–5mA). For common-anode LED rows, use SN74HC244AN outputs in sink mode (LED anode to VCC, cathode to Yn); for common-cathode, use source mode (anode to Yn, cathode to GND). Always include series current-limiting resistors - e.g., 470Ω at 5V yields ~6mA - to prevent exceeding absolute max ratings.

What is the maximum capacitive load the SN74HC244AN can drive reliably?

The SN74HC244AN is characterized up to 150pF load capacitance, with switching parameters (tpd, ten, tdis) guaranteed across that range. At CL = 150pF and VCC = 6V, typical propagation delay is 20ns and enable time is 26ns. For loads >150pF, signal integrity degrades - rise/fall times increase and ringing may occur. To drive heavier loads, add series damping resistors (e.g., 22Ω–47Ω) near the output or use dedicated buffer/driver ICs; do not exceed the 35mA total continuous output current limit per device.