STMicroelectronics 74ACT244MTR

Overview

74ACT244MTR from STMicroelectronics is an advanced high-speed CMOS octal non-inverting bus buffer with 3-state outputs, designed for bidirectional data bus interfacing between TTL, NMOS, and CMOS systems. It features 4.6 ns typical propagation delay at 5 V, ±24 mA symmetrical output drive, 4.5–5.5 V operating range, and 2 kV ESD immunity-used in memory address driver circuits and high-speed bus isolation.

For engineers reviewing the 74ACT244MTR datasheet, 74ACT244MTR pinout, 74ACT244MTR application, or 74ACT244MTR equivalent, key selection criteria include 3-state enable timing (tPZL/tPHZ ≤ 11.5 ns), transmission-line driving capability into 50 Ω, VIH/VIL compatibility with TTL logic levels, and SO-20 package thermal and routing constraints.

Technical Context

This device implements two independent 4-bit non-inverting buffer groups, each controlled by a dedicated 3-state enable input (1G and 2G). All inputs accept TTL-compatible thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V at VCC = 4.5–5.5 V) and drive 50 Ω transmission lines directly without external termination.

Propagation delays are balanced (tPLH ≅ tPHL), output impedance is symmetrical (|IOH| = IOL ≥ 24 mA), and quiescent ICC is limited to 4 µA max at 25°C-enabling low-power, high-noise-margin bus buffering in mixed-logic-level systems.

Key Specifications

Pinout & Package

74ACT244MTR is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package per JEDEC MS-013, with 0.300-inch body width and 1.27 mm pitch. Pin 1 is marked by a beveled corner or notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT244N and 74VHC244M, the 74ACT244MTR delivers optimal balance of speed, drive strength, and SOIC thermal performance for high-reliability 5 V bus applications-making it preferred for automated SMT production and dense layout scenarios.

Availability

74ACT244MTR is available at Aetrix Electronics and suitable for memory subsystems, microprocessor expansion interfaces, industrial backplane interconnects, and legacy equipment upgrades requiring stable component supply and long-term sourcing continuity.

Supply support for 74ACT244MTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The 74ACT family targets high-speed, low-power logic interfacing-specifically engineered to bridge TTL, CMOS, and NMOS systems while delivering robust ESD immunity and transmission-line drive capability.

FAQ

Is 74ACT244MTR compatible with 5 V TTL logic families?

Yes. Its input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V at VCC = 4.5–5.5 V) and output drive (VOH ≥ 3.86 V at IOH = –24 mA, VOL ≤ 0.5 V at IOL = 24 mA) meet or exceed standard TTL voltage specifications, ensuring reliable interoperability without level-shifting circuitry.

What is the maximum clock frequency supported for bus switching?

Based on tPD = 4.6 ns (typ), tPZL/tPHZ ≤ 11.5 ns, and balanced edge delays, the device supports reliable operation up to approximately 100 MHz for burst-mode address/data strobing-subject to PCB layout, load capacitance, and termination compliance.

Does 74ACT244MTR require external pull-up or pull-down resistors on enable inputs?

No. The 1G and 2G inputs have CMOS-compatible input structure with ±0.1 µA leakage (max) and defined VIH/VIL thresholds. When driven actively to VCC or GND, external biasing resistors are unnecessary-though local decoupling near VCC/GND remains critical for noise immunity.

Can 74ACT244MTR drive unterminated 50 Ω coaxial cables?

It is rated for 50 Ω transmission-line driving capability, but sustained use with unterminated coax may cause reflections and ringing. For reliable operation, match source impedance (via series resistor if needed) and terminate at the far end-especially beyond 10 cm or above 25 MHz.