Texas Instruments CD54HCT243F3A

Overview

CD54HCT243F3A from Texas Instruments is a high-speed CMOS quad-bus transceiver with three-state outputs, designed for bidirectional asynchronous communication between data buses in military/aerospace systems. It features 7ns typical propagation delay (A→B/B→A at V_CC = 5V, C_L = 15pF), ±25mA output drive, and operates across -55°C to +125°C - enabling robust bus interfacing in avionics backplanes and radiation-tolerant control modules.

For engineers reviewing the CD54HCT243F3A datasheet, CD54HCT243F3A pinout, CD54HCT243F3A application, or CD54HCT243F3A equivalent, key selection criteria include its HCT-level LSTTL input compatibility (V_IL ≤ 0.8V, V_IH ≥ 2.0V), 15-LSTTL load drive capability, and CERDIP-14 packaging for hermetic reliability in extended temperature environments.

Technical Context

The CD54HCT243F3A implements dual independent direction-control logic via OEA and OEB inputs, enabling simultaneous A-to-B and B-to-A data flow control per channel pair. Its silicon-gate CMOS architecture delivers TTL-compatible input thresholds while maintaining CMOS quiescent current (≤160µA over full temperature range) and low dynamic power dissipation (C_PD = 91pF).

Three-state output behavior is strictly governed by the truth table: both OEA and OEB high disables all outputs (high-Z); both low enables bidirectional pass-through; mismatched states force unidirectional flow (A→B or B→A). Input leakage remains ≤±1µA, and output transition times are balanced (t_TLH/t_THL ≤ 18ns at V_CC = 5V, C_L = 50pF).

Key Specifications

Pinout & Package

CD54HCT243F3A uses a 14-lead CERDIP (ceramic dual in-line package) with 0.3-inch body width and 0.1-inch lead pitch. The package is hermetically sealed for moisture resistance and thermal stability in extended temperature operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus transceiver applications.

Compared with CD54HCT243F3A, CD74HCT243M trades hermetic reliability for lower cost and smaller footprint in benign environments, while SN74HCT243N sacrifices temperature range for rapid availability and socket compatibility - neither offers the full military-grade qualification envelope of the CERDIP variant.

Availability

CD54HCT243F3A is available at Aetrix Electronics and suitable for avionics data bus interface, military vehicle control backplane, satellite onboard computer expansion, and radiation-hardened telemetry hub applications requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for CD54HCT243F3A 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 over 90 years of innovation in high-reliability components.

CD54HCT243F3A belongs to TI's military-qualified logic portfolio, engineered specifically for aerospace, defense, and industrial systems demanding guaranteed operation from -55°C to +125°C in mission-critical signal routing.

FAQ

What is the maximum clock frequency supported by CD54HCT243F3A in bidirectional bus applications?

The CD54HCT243F3A does not operate on a clock signal - it is an asynchronous transceiver. Its usable data rate is determined by propagation delay (9ns max) and output transition time (18ns max), supporting reliable bus toggling up to approximately 50MHz in well-terminated 50pF-load configurations. System-level timing must account for worst-case setup/hold margins relative to controlling logic edges.

Does CD54HCT243F3A require external pull-up or pull-down resistors on its I/O pins?

Yes - the CD54HCT243F3A datasheet explicitly recommends terminating all A_n and B_n I/O terminals with 10kΩ to 1MΩ resistors in high-impedance (three-state) modes to prevent floating inputs from inducing excessive currents or latch-up. This is critical for system stability during power sequencing or partial bus disable scenarios.

Can CD54HCT243F3A be used with 3.3V logic systems?

No - CD54HCT243F3A is specified only for 4.5V to 5.5V operation and requires LSTTL-compatible input thresholds (V_IL ≤ 0.8V, V_IH ≥ 2.0V). Direct connection to 3.3V logic violates its input voltage range and risks unreliable switching or increased ICC. A level-shifting solution such as SN74AVC4T245 is required for 3.3V ↔ 5V interfacing.

What is the thermal resistance (θ_JA) of the CD54HCT243F3A CERDIP package?

The CD54HCT243F3A uses a 14-lead CERDIP (J package) for which θ_JA is not characterized in the datasheet - the "N/A for Pkg Type" notation in TI's packaging addendum confirms no JEDEC-standard thermal resistance value is provided. Thermal design must rely on board-level measurements or vendor-provided thermal simulation models for the specific mounting configuration.

Is CD54HCT243F3A RoHS compliant?

CD54HCT243F3A carries a TBD eco-plan designation per TI's packaging addendum, indicating its lead/ball finish (A42) and RoHS status were not formally documented at time of publication. As a military-spec CERDIP device manufactured prior to full RoHS enforcement, it may contain leaded solder seals; users requiring RoHS compliance should verify conformance via TI's official material declarations or select CD74HCT243M (Green/RoHS-compliant SOIC variant).