Texas Instruments CD54HCT273F

Overview

CD54HCT273F from Texas Instruments is a high-speed CMOS octal D-type flip-flop with asynchronous active-low reset, designed for synchronous data latching in 8-bit bus systems. It operates at 4.5V–5.5V, features positive-edge clock triggering, supports –55°C to +125°C operation, and delivers 30 ns typical propagation delay (CL = 50 pF) with TTL-compatible inputs (VIH ≥ 2 V, VIL ≤ 0.8 V).

For engineers reviewing the CD54HCT273F datasheet, CD54HCT273F pinout, CD54HCT273F application, or CD54HCT273F equivalent, this device serves as a radiation-tolerant, military-grade register for data synchronization, bus isolation, and temporary 8-bit storage in avionics, test equipment, and ruggedized control systems where wide temperature range and LSTTL interoperability are critical.

Technical Context

The CD54HCT273F integrates eight identical D-type flip-flops sharing one common clock (CLK) and one active-low asynchronous clear (CLR), enabling simultaneous latching or resetting of all eight Q outputs. Its HCT logic family ensures direct compatibility with legacy LSTTL drivers while maintaining CMOS power efficiency.

Each flip-flop captures D-input data on the rising edge of CLK; CLR overrides clocking and forces all Q outputs low regardless of CLK state. Input leakage is ≤1 μA at VCC = 5.5 V, and output drive capability meets 4 mA sink/source under TTL loads - verified across –55°C to +125°C.

Key Specifications

Pinout & Package

J-lead Ceramic Dual In-line Package (CDIP), 20-pin, 26.92 mm × 6.92 mm body size with hermetic seal - suitable for high-reliability, high-temperature, and radiation-prone applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal D-type flip-flop applications.

Compared with CD74HCT273M and SN74HCT273N, the CD54HCT273F provides guaranteed operation across –55°C to +125°C, hermetic J-package construction, and compliance with MIL-PRF-38535 screening - making it the sole option for flight-critical, downhole, or long-life embedded systems where reliability cannot be compromised.

Availability

CD54HCT273F is available at Aetrix Electronics and suitable for avionics data acquisition, industrial PLC I/O modules, test equipment pattern generators, and ruggedized communication interfaces requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD54HCT273F 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 and aerospace component design.

The CD54HCT273F belongs to TI's CD54HCT logic family - engineered specifically for high-reliability applications demanding extended temperature operation, radiation tolerance, and MIL-qualified packaging.

FAQ

What is the maximum clock frequency supported by the CD54HCT273F?

The CD54HCT273F supports a maximum clock frequency of 25 MHz at 25°C, derating to 20 MHz over –40°C to +85°C and 16 MHz across its full –55°C to +125°C operating range. This is determined by the 45 ns maximum propagation delay (tPLH/tPHL) and minimum pulse width requirements for both CLK and CLR signals as specified in the official TI datasheet SCHS174D.

Does the CD54HCT273F require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs on the CD54HCT273F, including D, CLK, and CLR, must be terminated to either VCC or GND to prevent floating states that cause excessive current draw, oscillation, or undefined output behavior. A 10 kΩ resistor is recommended for pull-up/pull-down; direct connection is acceptable if the input remains permanently inactive.

Can the CD54HCT273F drive standard LSTTL loads directly?

Yes - the CD54HCT273F is explicitly designed for direct LSTTL compatibility. Its VIH(min) = 2.0 V and VIL(max) = 0.8 V match LSTTL input thresholds, and its outputs deliver ±4 mA drive strength into TTL loads - sufficient to drive up to 10 LSTTL inputs per output without external buffers.

What package type does the CD54HCT273F use, and why is it significant?

The CD54HCT273F uses a 20-pin J-lead Ceramic Dual In-line Package (CDIP). This hermetically sealed ceramic package provides superior moisture resistance, thermal stability, and radiation hardness - essential for aerospace, defense, and downhole applications where plastic packages would fail under thermal cycling or ionizing radiation exposure.

How does the asynchronous CLR function interact with the clock signal in the CD54HCT273F?

The CLR input on the CD54HCT273F is asynchronous and active-low: when pulled low, it forces all eight Q outputs immediately to logic 0 - regardless of CLK state, edge, or timing. This override behavior occurs independently of clock edges and takes priority over data capture, enabling instantaneous system reset without waiting for the next clock cycle.