STMicroelectronics M74HCT373B1R

Overview

M74HCT373B1R from STMicroelectronics is a high-speed CMOS octal D-type transparent latch with 3-state non-inverting outputs, pin- and function-compatible with standard 74-series 373 devices. It features 19 ns typical propagation delay (D→Q) at VCC = 4.5 V, ±6 mA output drive capability, and operates across –55 °C to +125 °C. Used in bus-oriented digital systems for data latching and isolation, such as microcontroller address/data bus buffering.

For engineers reviewing the M74HCT373B1R datasheet, M74HCT373B1R pinout, M74HCT373B1R application, or M74HCT373B1R equivalent, key selection criteria include 3-state output timing (tPZL/tPLZ ≤ 45 ns), latch enable pulse width (tW(H) ≥ 8 ns min), input compatibility with TTL logic levels (VIH ≥ 2.0 V, VIL ≤ 0.8 V), and industrial temperature range support.

Technical Context

The M74HCT373B1R implements an 8-bit transparent latch architecture controlled by independent LE (latch enable) and OE (output enable) inputs. Its dual-control logic allows simultaneous data capture on LE low-to-high edge transition and tri-state output control via active-low OE, enabling time-multiplexed bus sharing.

Designed using sub-micron silicon gate C2MOS technology, it delivers symmetrical output impedance (|IOH| = IOL ≥ 6 mA), balanced propagation delays (tPLH ≅ tPHL), and integrated ESD/transient protection on all inputs - critical for noise-prone industrial bus environments.

Key Specifications

Pinout & Package

Package: Plastic DIP-20 (0.300" wide), JEDEC MS-001, 20-pin through-hole outline with 2.54 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT373N and 74VHC373SJX, the M74HCT373B1R uniquely combines extended industrial temperature range (–55 °C to +125 °C), robust 6 mA drive, and proven reliability in legacy-replacement scenarios - making it optimal for long-lifecycle, high-reliability applications.

Availability

M74HCT373B1R is available at Aetrix Electronics and suitable for microcontroller bus interfacing, industrial PLC backplanes, automotive body control modules, and legacy system upgrades requiring stable component supply over extended product lifecycles.

Supply support for M74HCT373B1R 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, Switzerland, specializing in automotive, industrial, and power management ICs with broad manufacturing and quality certifications.

The M74HCT373B1R belongs to ST's high-speed HCT logic family, designed specifically for TTL-compatible, low-power, industrial-temperature digital interfacing in mission-critical embedded systems.

FAQ

What is the maximum clock frequency supported by the M74HCT373B1R?

The M74HCT373B1R is not a clocked register but a transparent latch controlled by LE. Its usable data rate depends on setup/hold timing: minimum LE pulse width is 8 ns (typ.), supporting effective latching up to ~60 MHz in ideal conditions. Real-world bus timing must account for tPLH/tPHL (≤45 ns max) and system-level routing delays.

Can the M74HCT373B1R drive LED indicators directly?

Yes - with IOL ≥ 6 mA per output and VOL ≤ 0.4 V at 6 mA, it can sink sufficient current for standard 2 mA LEDs (with appropriate series resistor). However, continuous DC drive should be limited to avoid exceeding total package power dissipation (500 mW at 65 °C), especially in high-ambient environments.

Is the M74HCT373B1R RoHS compliant?

Yes - the M74HCT373B1R (DIP-20 package) conforms to RoHS Directive 2011/65/EU. STMicroelectronics confirms lead-free terminations and halogen-free molding compound for this part number, with full compliance documentation available upon request.

How does the latch behavior differ between LE high and LE low states?

When LE is high, Q outputs follow D inputs in real time (transparent mode). When LE transitions low, the Q outputs freeze at the instantaneous D-input logic levels (latched state). Subsequent D-input changes have no effect until LE returns high - enabling precise sampling of asynchronous data edges.