STMicroelectronics 74ACT373TTR

Overview

74ACT373TTR from STMicroelectronics is a high-speed CMOS octal D-type transparent latch with 3-state non-inverting outputs, designed for bus interface and data buffering in TTL/CMOS mixed-signal systems. It features 6 ns typical propagation delay (D→Q), ±24 mA output drive, 4.5–5.5 V operating range, and pin/function compatibility with standard 74-series 373 devices.

For engineers reviewing the 74ACT373TTR datasheet, 74ACT373TTR pinout, 74ACT373TTR application, or 74ACT373TTR equivalent, key selection criteria include 3-state output control timing (tPZL/tPHZ ≤ 10.5 ns), latch enable setup/hold margins (ts = –0.5 ns, th = 0.5 ns), and 50 Ω transmission line driving capability under industrial temperature range (–40°C to +85°C).

Technical Context

This device implements an edge-transparent latch architecture controlled by LE (latch enable) and OE (output enable). When LE is HIGH, Q outputs follow D inputs; when LE transitions LOW, data is latched. OE independently controls 3-state output impedance: LOW enables normal logic levels, HIGH forces high-impedance state.

Designed using sub-micron C2MOS technology, it delivers symmetrical output drive (|IOH| = IOL ≥ 24 mA), balanced tPLH ≈ tPHL propagation delays, and 2 kV ESD protection on all I/O pins. Its input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) ensure direct interfacing with TTL outputs without level-shifting.

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5 mm × 4.4 mm body, 0.65 mm pitch, thin shrink small outline profile suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT373PW, 74ACT373TTR offers identical functionality and timing but differs in manufacturer qualification and traceability; versus 74LCX373MTCX, it supports full 5 V operation and TTL interfacing - critical for legacy system integration where voltage translation adds cost and board space.

Availability

74ACT373TTR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy bus interface adapters, test equipment digital pattern generators, and automated test fixture controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74ACT373TTR 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, specializing in automotive, industrial, and power management solutions with broad analog, digital, and mixed-signal portfolios.

The 74ACT series targets high-speed, low-power logic interfacing in industrial and telecom infrastructure, emphasizing TTL compatibility, robust ESD immunity, and wide temperature operation without sacrificing speed.

FAQ

What is the maximum clock frequency supported by 74ACT373TTR in transparent mode?

The 74ACT373TTR does not operate on a clock signal - it is a transparent latch controlled by the LE input. In transparent mode (LE = HIGH), data appears at Q outputs with 6 ns typical delay. Maximum usable data rate depends on LE pulse width (min 1.3 ns at 25°C) and setup/hold timing; for 10 MHz bus operation, it meets all AC timing requirements including tW(LE), ts, and th.

Can 74ACT373TTR drive a 50 Ω transmission line directly without series termination?

Yes - the datasheet explicitly guarantees 50 Ω transmission line driving capability at VCC = 4.5–5.5 V. With symmetrical 24 mA output drive and matched output impedance, it can launch clean edges onto 50 Ω PCB traces up to 15 cm without external series resistors, provided load capacitance remains ≤ 50 pF per output.

Is 74ACT373TTR compatible with 3.3 V logic inputs?

No - its input thresholds (VIH ≥ 2.0 V min, VIL ≤ 0.8 V max) are specified for 5 V operation. While 3.3 V logic HIGH may meet VIH under some conditions, STMicroelectronics does not guarantee reliable operation below VCC = 4.5 V, and interfacing with 3.3 V systems requires level translation to avoid marginal switching or increased ICC.

What is the purpose of the a1 and A1 dimensions in the TSSOP-20 mechanical drawing?

The a1 dimension (0.05–0.15 mm) defines the seating plane height from the bottom of the package body to the tip of the leads, critical for solder paste volume control and coplanarity verification. A1 (0.05–0.15 mm) specifies the lead thickness - both govern reflow profile settings and IPC Class 2/3 solder joint reliability during SMT assembly.