Texas Instruments SN74ALS244CDBR

Overview

SN74ALS244CDBR from Texas Instruments is an octal non-inverting buffer/line driver with 3-state outputs, designed for memory address driving, bus interfacing, and clock distribution in TTL-compatible systems. It operates from 4.5 V to 5.5 V, supports 0°C to 70°C ambient, delivers ±12 mA output drive, features pnp input structure to reduce DC loading, and uses a 20-pin SSOP (DB) package.

For engineers reviewing the SN74ALS244CDBR datasheet, SN74ALS244CDBR pinout, SN74ALS244CDBR application, or SN74ALS244CDBR equivalent, key selection criteria include 3-state bus-driving capability, ALS logic family speed-power tradeoff, industrial temperature range compliance, and SSOP footprint compatibility with space-constrained PCB layouts.

Technical Context

This device implements two independent 4-bit groups (1A–1Y and 2A–2Y), each controlled by its own active-low 3-state enable (1OE, 2OE). The pnp input stage minimizes input current draw, improving fanout in dense TTL bus environments. Output logic follows positive-logic buffering: when OE is low, Y mirrors A; when OE is high, Y enters high-impedance state.

Propagation delays are specified at CL = 50 pF: tPLH/tPHL ≤ 10 ns (A→Y), tPZH/tPZL ≤ 20 ns (OE→Y), and tPHZ/tPLZ ≤ 10 ns (OE→Y). All timing parameters are guaranteed across the full 0°C to 70°C operating range and 4.5 V–5.5 V supply.

Key Specifications

Pinout & Package

SN74ALS244CDBR uses a 20-pin Shrink Small-Outline Package (SSOP), 0.65 mm pitch, 7.5 mm × 5.6 mm body, 2.0 mm max height, with gull-wing leads and pin 1 index area marked.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALS244CDWR and SN74AS244ADWR, SN74ALS244CDBR provides optimal balance of compact SSOP packaging, industrial temperature support, and ALS-class power efficiency - making it ideal for retrofitting legacy systems where board space and thermal headroom are constrained.

Availability

SN74ALS244CDBR is available at Aetrix Electronics and suitable for memory address buffering, parallel bus interface, clock distribution, and legacy system backplane applications requiring stable component supply and long-term industrial availability.

Supply support for SN74ALS244CDBR 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 decades of heritage in TTL and advanced logic families.

The SN74ALS244CDBR belongs to TI's legacy ALS logic product line, engineered for reliable, low-power, high-fanout buffering in industrial control, instrumentation, and retrofitted computing systems.

FAQ

What is the maximum operating supply voltage for SN74ALS244CDBR?

The absolute maximum supply voltage for SN74ALS244CDBR is 7 V, but the recommended operating range is strictly 4.5 V to 5.5 V. Operation outside this range may cause permanent damage or unpredictable behavior. The device is optimized for standard 5 V TTL systems, and exceeding 5.5 V voids parametric guarantees including VOH, VOL, and timing.

Does SN74ALS244CDBR support hot-swap or live-insertion?

No, SN74ALS244CDBR does not support hot-swap. Its absolute maximum ratings do not include powered insertion stress testing, and the 3-state outputs lack bus-hold or Ioff protection. Applying VCC before or after signal inputs may cause latch-up or excessive current flow. Always power-cycle the entire system before inserting or removing SN74ALS244CDBR.

Can SN74ALS244CDBR drive a 50-pF load with guaranteed timing?

Yes - SN74ALS244CDBR's switching characteristics (tPLH, tPHL, tPZH, etc.) are explicitly characterized at CL = 50 pF, R1 = R2 = 500 Ω, and VCC = 4.5 V–5.5 V. All timing parameters in the datasheet assume this load condition, so 50 pF represents the reference design point, not a limit. For heavier loads, propagation delay increases predictably per capacitive loading models in TI's ALS application notes.

Is SN74ALS244CDBR pin-compatible with SN74ALS244CN?

Yes, SN74ALS244CDBR is functionally and pinout-compatible with SN74ALS244CN (PDIP-20), sharing identical pin numbering, signal assignments, and electrical behavior. However, the SSOP (DB) package requires different PCB footprint, solder paste stencil, and reflow profile - mechanical adaptation is needed, but no logic or schematic changes are required.

What is the purpose of the pnp input structure in SN74ALS244CDBR?

SN74ALS244CDBR uses pnp input transistors to minimize input current (II ≤ 0.1 mA), significantly reducing DC loading on upstream drivers. This increases effective fanout - one SN74ALS244CDBR input can drive up to 20 ALS gates or 10 LS-TTL loads - which is essential for maintaining signal integrity in dense memory address or control bus applications.