Texas Instruments CD54HC273F

Overview

CD54HC273F 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 digital systems. It operates from 2V to 6V, features positive-edge clock triggering, and delivers propagation delay as low as 26 ns (at VCC = 6V, CL = 50 pF), enabling reliable operation in military-grade temperature ranges (–55°C to +125°C). Its primary role is edge-triggered data capture and storage in bus interface, control logic, and register file applications.

For engineers reviewing the CD54HC273F datasheet, CD54HC273F pinout, CD54HC273F application, or CD54HC273F equivalent, this device serves as a radiation-tolerant, wide-temperature latch for deterministic timing alignment-especially where LSTTL compatibility is not required but low power, noise immunity (NIL/NIH = 30% at VCC = 5V), and robust DC specs are critical.

Technical Context

The CD54HC273F implements eight independent D-type flip-flops sharing one common clock (CLK) and one asynchronous clear (CLR) input, all fabricated using silicon-gate CMOS technology. Its architecture enforces strict setup (tSU = 10 ns min at VCC = 6V) and hold (tH = 3 ns) timing relative to CLK's rising edge, with CLR asserting Q outputs to logic 0 independently of clock state.

It uses standard CMOS inputs (not TTL-compatible), supports fanout of 10 LSTTL loads, and exhibits balanced push-pull output drive (±25 mA per pin, VOH = 5.9 V, VOL = 0.1 V at VCC = 6V). Quiescent current remains below 160 μA over full temperature range, and input capacitance is fixed at 10 pF-key for high-frequency stability in synchronous designs.

Key Specifications

Pinout & Package

J-lead Ceramic Dual In-line Package (CDIP), 20-pin, 26.92 mm × 6.92 mm body size with through-hole mounting. Hermetically sealed for high-reliability mil-spec applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD54HC273F, CD74HC273E trades temperature range and package robustness for lower cost and wider availability, while SNJ54HC273FK adds process controls and test rigor for mission-critical deployment - all three share identical logic behavior and pinout.

Availability

CD54HC273F is available at Aetrix Electronics and suitable for industrial control bus interface, aerospace avionics data capture, and military embedded system bootloader applications requiring stable component supply across extended temperature and long lifecycle commitments.

Supply support for CD54HC273F 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 decades of heritage in high-reliability military and aerospace components.

The CD54HC273F belongs to TI's CDx4HC(T)273 family of high-speed CMOS octal D flip-flops, engineered specifically for deterministic data synchronization in extreme-temperature, low-power, and noise-immune digital systems.

FAQ

What is the maximum clock frequency supported by the CD54HC273F?

The CD54HC273F supports a maximum clock frequency of 35 MHz at VCC = 6V and TA = 25°C, dropping to 23 MHz at –55°C to +125°C. This is derived from its guaranteed propagation delay (tPLH/tPHL ≤ 38 ns at VCC = 4.5V, full temperature range) and minimum clock pulse width (tW ≥ 15 ns). The CD54HC273F achieves this performance while maintaining full functionality across its entire military temperature range - a key differentiator versus commercial-grade alternatives.

Does the CD54HC273F support TTL-level input signals?

No, the CD54HC273F does not support direct TTL-level inputs. As an HC-type device, it requires VIH ≥ 3.15 V (at VCC = 4.5V) and VIL ≤ 1.35 V - incompatible with standard TTL's 2.0 V VIH min and 0.8 V VIL max. For TTL-compatible operation, the HCT variant (e.g., CD54HCT273F) must be used. Using TTL outputs directly with CD54HC273F risks invalid logic states and increased power consumption due to input stage contention.

How is the CD54HC273F reset function implemented, and what timing constraints apply?

The CD54HC273F uses an asynchronous active-low CLR input that forces all eight Q outputs to logic 0 immediately, independent of CLK. Its minimum pulse width is 15 ns at VCC = 6V over full temperature range. Critical timing includes tREM (removal time from CLR deassertion to next CLK edge) of 13 ns max - violating this may cause metastability. The CD54HC273F's CLR is fully static; no minimum high-time requirement exists once asserted.

Can unused inputs on the CD54HC273F be left floating?

No, unused inputs on the CD54HC273F must never be left floating. As a CMOS device, floating inputs cause excessive current draw, oscillation, and potential device damage. All unused D inputs and CLK/CLR must be tied to VCC or GND via hard connection or 10 kΩ pull-up/down resistors. This requirement is explicitly stated in TI's datasheet Section 7.3.2 and applies equally to all eight D inputs, even if only some channels are used in a given design.

What decoupling capacitance is recommended for the CD54HC273F?

Texas Instruments recommends a 0.1 μF ceramic capacitor placed as close as possible between VCC (pin 20) and GND (pin 10) for each CD54HC273F. For improved high-frequency noise rejection, a parallel 1 μF capacitor is advised. This local decoupling prevents supply droop during simultaneous output switching - essential given the CD54HC273F's ±25 mA per-output drive strength and fast edge rates. Layout guidelines specify short, wide traces and shared ground plane beneath the device.