Texas Instruments CD74FCT824AEN

Overview

CD74FCT824AEN from Texas Instruments is a 9-bit, positive-edge-triggered D-type flip-flop with 3-state outputs, BiCMOS process technology, inverted outputs, and buffered inputs. It delivers 48-mA sink current per output, limits output voltage swing to 3.7 V, and operates across 0°C to 70°C - designed for high-capacitance bus interfacing in microprogrammed systems.

For engineers reviewing the CD74FCT824AEN datasheet, CD74FCT824AEN pinout, CD74FCT824AEN application, or CD74FCT824AEN equivalent, key selection criteria include 3-state bus isolation, clock-enable and asynchronous clear control, low-EMI output swing, and compatibility with 5-V TTL-level logic systems.

Technical Context

The CD74FCT824AEN implements nine independent D-type flip-flops sharing common CLK, CLKEN, CLR, and OE signals. Its BiCMOS output stage combines bipolar pull-down and CMOS pull-up transistors to limit VOH to ~3.7 V at VCC = 5 V, reducing simultaneous switching noise and ground bounce.

Operation requires strict timing: minimum 4 ns setup/hold for data and CLKEN relative to CLK↑, 7 ns minimum pulse width on CLK and CLR, and supports up to 70 MHz clock frequency. The device features input/output isolation from VCC and SCR latch-up resistance.

Key Specifications

Pinout & Package

Packaged in 24-pin plastic dual in-line package (PDIP), with through-hole mounting and industry-standard pin spacing (0.3 inch width).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 9-bit bus-interface flip-flop applications.

Compared with CD74FCT824AEN, SN74FCT244N offers simpler buffering but no storage, while CD74ACT273E provides registered logic at lower ICC yet lacks integrated bus control - making CD74FCT824AEN uniquely suited for parity-aware, clock-gated, high-drive bus interfaces.

Availability

CD74FCT824AEN is available at Aetrix Electronics and suitable for parity bus interfacing, I/O port expansion, working register banks, and high-capacitance bus driver applications requiring stable component supply and legacy 5-V TTL compatibility.

Supply support for CD74FCT824AEN 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 logic families.

The CD74FCT824AEN belongs to the FCT-series BiCMOS logic product line, engineered for high-speed, low-noise 5-V bus interfacing in commercial and industrial systems where EMI control and drive strength are critical.

FAQ

What is the maximum clock frequency supported by the CD74FCT824AEN?

The CD74FCT824AEN supports a maximum clock frequency of 70 MHz under recommended operating conditions (VCC = 4.75 V to 5.25 V, TA = 0°C to 70°C). This rating is validated by timing parameters including 7 ns minimum CLK pulse width and 7.5 ns typical CLK-to-Q propagation delay, ensuring reliable setup/hold timing margins in high-speed bus applications.

Does the CD74FCT824AEN have true 3-state outputs, and how is output enable controlled?

Yes, the CD74FCT824AEN features true 3-state outputs controlled by the OE (output enable) pin. When OE is high, all nine Q outputs enter high-impedance state regardless of clock, data, or clear status - enabling clean bus sharing without contention. OE operates asynchronously and independently of register functionality, allowing dynamic bus arbitration without disrupting stored data.

What is the purpose of the CLKEN pin on the CD74FCT824AEN?

The CLKEN (clock enable) pin on the CD74FCT824AEN disables the internal clock buffer when driven high, effectively freezing the Q outputs at their last registered values without resetting the flip-flop state. This allows deterministic pause/resume behavior in synchronous data paths - for example, halting register updates during debug cycles or power-save modes while preserving data integrity in the CD74FCT824AEN.

How does the CD74FCT824AEN reduce electromagnetic interference (EMI)?

The CD74FCT824AEN reduces EMI through two integrated mechanisms: (1) limiting VOH to 3.7 V (two diode drops below VCC), which lowers ΔV/Δt and suppresses power-bus ringing; and (2) controlling output edge rates to minimize simultaneous switching noise. These features are inherent to its BiCMOS output stage and are confirmed in the noise characteristics table (VOL(P) ≤ 1 V, VOH(V) ≥ 0.5 V at CL = 50 pF).

Is the CD74FCT824AEN compatible with standard TTL logic levels?

Yes, the CD74FCT824AEN is fully compatible with standard TTL logic levels: VIH = 2.0 V (minimum) and VIL = 0.8 V (maximum) align with TTL input thresholds, and its 48-mA sink capability and 3.7-V VOH ensure robust driving of TTL loads. This compatibility is explicitly validated in the recommended operating conditions and electrical characteristics tables of the CD74FCT824AEN datasheet.