Texas Instruments SN74AC244N

Overview

SN74AC244N from Texas Instruments is an octal non-inverting buffer/driver with 3-state outputs, designed for bus-oriented receivers and transmitters in memory address and clock distribution systems. It operates from 2V to 6V V_CC, supports 5V logic levels with 7.5ns max propagation delay, and features independent output-enable controls for two 4-bit channels - used in LED displays and telecom infrastructure.

For engineers reviewing the SN74AC244N datasheet, SN74AC244N pinout, SN74AC244N application, or SN74AC244N equivalent, this page delivers verified functional modes, thermal resistance (69°C/W), input voltage tolerance up to 6V, 3-state output behavior, and PDIP-20 package-specific layout guidance.

Technical Context

The SN74AC244N implements two independent 4-bit non-inverting buffers, each controlled by its own active-low output-enable (OE) input. When OE is low, data passes transparently from A inputs to Y outputs; when high, outputs enter high-impedance state - enabling bidirectional bus control without external direction logic.

Its AC CMOS design ensures rail-to-rail input compatibility (VI up to V_CC + 0.5V), ±24mA output drive at 5V, and guaranteed operation across –40°C to +85°C. The device meets JEDEC standard JESD8-5 for 3.3V/5V mixed-voltage interfacing and supports hot-swap capable bus isolation via fast enable/disable timing.

Key Specifications

Pinout & Package

SN74AC244N uses a 20-pin Plastic Dual In-line Package (PDIP) with 0.300″ body width and 0.100″ lead pitch. Pin 1 is located at the left end of the top row (notch-side marking), and the package includes no thermal pad.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC244N and SN74LVC244APW, the SN74AC244N uniquely balances 5V system compatibility, 7.5ns speed, ±24mA drive, and through-hole PDIP packaging - making it the only choice for legacy industrial boards requiring drop-in replacement of older AC-series buffers without layout changes.

Availability

SN74AC244N is available at Aetrix Electronics and suitable for LED displays, telecom infrastructure, and motor-drive control boards requiring stable component supply and long-term industrial availability.

Supply support for SN74AC244N 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 for industrial, automotive, and communications markets.

The SN74AC244N belongs to TI's classic AC logic family, engineered for high-speed, low-power 3-state bus interfacing in mixed-voltage systems - targeting industrial control, telecom, and legacy computing applications.

FAQ

What is the maximum operating voltage for SN74AC244N?

The SN74AC244N supports a supply voltage range of 2V to 6V. Its absolute maximum rating is 7V on V_CC, but sustained operation above 6V violates recommended conditions and risks reliability degradation. Inputs tolerate up to V_CC + 0.5V, allowing 6V signals even at minimum 2V V_CC. This makes SN74AC244N suitable for mixed-voltage board designs without level translators.

Does SN74AC244N support hot-swap or live insertion?

SN74AC244N is not explicitly rated for hot-swap, but its 3-state outputs and robust input clamp current (±20mA) provide inherent resilience during partial power-up. To enable safe live insertion, tie both OE pins to V_CC via 10kΩ pull-up resistors and ensure GND connects before V_CC. This forces outputs into high-Z before power stabilization - a technique validated in TI application report SCBA004 for SN74AC244N.

Can SN74AC244N drive LEDs directly?

Yes, SN74AC244N can drive LEDs directly: each output sources or sinks up to ±24mA at 4.5–5.5V V_CC, sufficient for standard 20mA LED segments. For common-anode displays, connect LED anodes to V_CC and cathodes to SN74AC244N outputs; for common-cathode, reverse the connection. Always include series current-limiting resistors calculated using V_OL ≈ 0.44V at 24mA (per datasheet Table 5.4).

What is the thermal resistance (R_θJA) of SN74AC244N in PDIP package?

The junction-to-ambient thermal resistance (R_θJA) for SN74AC244N in the PDIP-20 package is 69°C/W, as specified in Section 5.3 of the official datasheet. This value assumes standard JEDEC test board conditions (2S2P). Actual board-level performance depends on copper area, airflow, and nearby heat sources - derate output current if ambient exceeds 70°C or if multiple outputs switch simultaneously at full load.

How does the output-enable timing affect bus arbitration in SN74AC244N?

SN74AC244N provides fast 3-state enable/disable: t_PZH and t_PZL are ≤10.5ns at 5V, ensuring rapid bus release during master handoff. This minimizes bus contention windows in multi-controller systems. For reliable arbitration, assert OE high ≥15ns before releasing control, and verify that downstream receivers meet setup time relative to the last valid Y output transition - confirmed in switching characteristics Tables 5.5 and 5.6 for SN74AC244N.