Texas Instruments CD54HC245F3A

Overview

CD54HC245F3A from Texas Instruments is a high-speed CMOS octal bus transceiver with three-state non-inverting outputs, designed for bidirectional asynchronous data transfer between buses. It operates across 2 V to 6 V supply voltage, delivers 9 ns typical propagation delay (VCC = 5 V, CL = 15 pF), supports -55°C to +125°C military-grade temperature range, and drives up to 15 LSTTL loads - enabling robust inter-bus communication in avionics and industrial control backplanes.

For engineers reviewing the CD54HC245F3A datasheet, CD54HC245F3A pinout, CD54HC245F3A application, or CD54HC245F3A equivalent, key selection considerations include its CDIP-20 package with SNPB lead finish, direction-controlled bidirectional flow, three-state output enable logic, and compatibility with both CMOS and TTL input thresholds in HC-family operation.

Technical Context

The CD54HC245F3A implements an octal bidirectional buffer architecture where all eight channels share a common DIR (direction) control input and OE (output enable) input. Its logic determines data flow direction (A→B or B→A) and enables/disables output drivers simultaneously, ensuring clean bus isolation during high-impedance states.

It uses standard HC-series silicon with rail-to-rail CMOS input thresholds (VIH = 3.15 V, VIL = 1.35 V at VCC = 4.5 V), exhibits balanced rise/fall times (10–15 ns), and maintains stable performance across full military temperature range without derating - critical for deterministic timing in safety-critical subsystems.

Key Specifications

Pinout & Package

CD54HC245F3A is housed in a hermetically sealed Ceramic Dual In-line Package (CDIP, J-body), 20-pin, 26.92 mm × 6.92 mm footprint with SNPB (tin-lead) leads and no moisture sensitivity rating (N/A for Pkg Type). The package is rated for manual and wave soldering only - not reflow-compatible.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC245E, CD54HC245F3A offers superior moisture resistance and long-term reliability in sealed enclosures, while CD54HCT245F3A trades HC's wider supply range for guaranteed TTL input compatibility - making CD54HC245F3A optimal for high-reliability, wide-VCC, hermetically sealed deployments.

Availability

CD54HC245F3A is available at Aetrix Electronics and suitable for avionics data bus interfaces, industrial PLC backplanes, defense radar signal processing, and downhole oilfield instrumentation requiring stable component supply across extended temperature and long product lifecycles.

Supply support for CD54HC245F3A 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 high-reliability logic solutions, with decades of heritage in military-qualified components.

The CD54HC245F3A belongs to TI's CD54/74HC(T) logic family, engineered specifically for high-speed, low-power, temperature-resilient digital interfacing in mission-critical systems where failure is not an option.

FAQ

What is the maximum clock frequency supported by CD54HC245F3A in a data bus application?

The CD54HC245F3A does not operate on a clock; it is a combinational transceiver. Its usable data rate depends on propagation delay and bus loading. With 19 ns max tpd at VCC = 6 V and CL = 50 pF, it supports reliable 8-bit parallel transfers up to approximately 26 MHz (1/2 × tpd) in point-to-point configurations. For longer buses or higher capacitance, derating is required - the CD54HC245F3A datasheet specifies timing under defined load conditions, not clocked operation.

Is CD54HC245F3A compatible with 3.3 V microcontroller I/O pins?

Yes, CD54HC245F3A is fully compatible with 3.3 V microcontrollers. Its HC-family input thresholds (VIH = 2.1 V min at VCC = 3.3 V) exceed typical 3.3 V logic high levels (~2.4–3.3 V), and its outputs swing rail-to-rail - delivering >3.0 V high and <0.1 V low when powered at 3.3 V. The CD54HC245F3A also tolerates VCC as low as 2 V, enabling direct interface without level-shifting circuitry.

Does CD54HC245F3A require external pull-up or pull-down resistors on DIR or OE pins?

No, CD54HC245F3A does not require external biasing on DIR or OE. Its CMOS inputs have ≤1 µA leakage current and defined VIH/VIL thresholds across the full supply range. Leaving DIR or OE floating risks undefined behavior - TI explicitly warns against unconnected inputs in Section 9.1. The CD54HC245F3A must be driven actively high or low; internal pull-ups/pull-downs are not integrated.

Can CD54HC245F3A be used in place of CD74HC245E in an existing design?

CD54HC245F3A can replace CD74HC245E electrically and functionally, but mechanical and process differences apply: CD54HC245F3A uses hermetic CDIP with SNPB leads (not RoHS), while CD74HC245E uses plastic PDIP with NiPdAu leads. Substitution requires verification of board-level soldering method (wave vs. reflow), environmental sealing needs, and compliance requirements - the CD54HC245F3A is not a drop-in replacement for RoHS or reflow-processed assemblies.

What is the thermal resistance (RθJA) of CD54HC245F3A in its CDIP package?

The CD54HC245F3A in CDIP (J) package does not specify RθJA in the datasheet because its hermetic ceramic construction and lead-frame geometry differ significantly from plastic packages. TI provides thermal data only for PDIP (N) and SOIC (DW) variants (69°C/W and 58°C/W respectively). For CD54HC245F3A, junction temperature must be estimated using power dissipation (ICC × VCC + dynamic Cpd × f × VCC²) and system-level thermal modeling - no published RθJA value exists for the J-body.