Texas Instruments CY74FCT823CTQCT

Overview

CY74FCT823CTQCT from Texas Instruments is a 9-bit positive-edge-triggered bus-interface register with 3-state outputs, buffered clock-enable (EN) and asynchronous clear (CLR), 64-mA sink / 32-mA source drive capability, and Ioff support for partial-power-down operation. It serves as a high-drive output port in parity bus interfacing for microprogrammed systems.

For engineers reviewing the CY74FCT823CTQCT datasheet, CY74FCT823CTQCT pinout, CY74FCT823CTQCT application, or CY74FCT823CTQCT equivalent, key selection criteria include its 6 ns propagation delay (tPLH/tPHL at CL = 50 pF), TTL-compatible input/output logic levels, matched rise/fall times, edge-rate control for noise suppression, and QSOP-24 package with Ioff-enabled power-down safety.

Technical Context

This device implements nine D-type flip-flops synchronized to the low-to-high transition of CP, with independent EN gating and active-low CLR overriding register state. Output enable (OE) controls 3-state Y0–Y8 outputs independently of clock or data flow.

Its FCT-family architecture features edge-rate controlled outputs to reduce simultaneous switching noise, Ioff circuitry that disables outputs when VCC = 0 V to prevent backflow current, and full compatibility with TTL voltage thresholds (VIH = 2 V min, VIL = 0.8 V max) while operating from 4.75–5.25 V.

Key Specifications

Pinout & Package

Package: QSOP-24 (DBQ), 3.9 mm × 8.7 mm body, 0.635 mm pitch, RoHS-compliant NIPDAU finish, MSL Level-2-260°C-1 year.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY74FCT823ATQCT, CY74FCT823CTQCT delivers tighter timing control for faster bus cycles; versus SN74FCT823CTSOCT, it offers smaller board area and improved high-frequency noise immunity via QSOP's shorter lead inductance-critical in compact embedded designs.

Availability

CY74FCT823CTQCT is available at Aetrix Electronics and suitable for industrial backplane interfaces, microprocessor parity expansion, and high-drive output port applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CY74FCT823CTQCT 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 interface and timing products.

CY74FCT823CTQCT belongs to TI's FCT logic family-designed specifically for robust, high-speed 5-V bus interfacing with noise resilience, power-down safety, and TTL compatibility in industrial and computing systems.

FAQ

What is the maximum clock frequency supported by CY74FCT823CTQCT?

CY74FCT823CTQCT does not specify a maximum clock frequency in its datasheet; instead, it defines timing via minimum pulse widths and setup/hold requirements. With t_w(CP) = 6 ns min and t_su/t_h ≤ 4 ns, it supports reliable operation up to approximately 83 MHz in ideal conditions. Real-world frequency depends on board layout, load capacitance, and signal integrity-designers should verify timing margins using worst-case propagation delays (6 ns) and skew.

Does CY74FCT823CTQCT support hot insertion or live insertion?

Yes, CY74FCT823CTQCT supports partial-power-down operation via its Ioff feature: when VCC = 0 V, output leakage is limited to ±1 µA, preventing damaging back-current from live buses into the unpowered device. This enables safe hot insertion in systems with controlled power sequencing, provided OE is held high during insertion to maintain outputs in high-Z state until VCC stabilizes.

How does the edge-rate control in CY74FCT823CTQCT improve system noise performance?

CY74FCT823CTQCT incorporates internal edge-rate control circuitry that limits the slew rate of output transitions, significantly reducing simultaneous switching noise (SSN) and ground bounce. Measured against non-controlled FCT variants, this results in lower peak current transients and cleaner power rail stability-especially critical in high-pin-count packages driving >50-pF loads, where unchecked dV/dt can induce crosstalk or false triggering in adjacent signals.

Can CY74FCT823CTQCT be used with 3.3-V logic systems?

No-CY74FCT823CTQCT is a 5-V-only device requiring VCC = 4.75–5.25 V and is not 3.3-V tolerant. Its inputs are TTL-compatible (VIH = 2.0 V min), so 3.3-V logic may not reliably drive it high; its outputs swing to ~3.3 V (VOH typ) but are designed to drive 5-V TTL loads. For 3.3-V systems, use TI's ALVC or LVC families instead-CY74FCT823CTQCT must be isolated via level translators or used only in pure 5-V domains.

What is the purpose of the CLR and EN inputs in CY74FCT823CTQCT, and how do they interact?

In CY74FCT823CTQCT, CLR is asynchronous and overrides all other controls: when low, it forces all Q and Y outputs low immediately, regardless of CP, EN, or OE state. EN is synchronous and gates the clock-only when EN is low does CP↑ transfer D inputs to Q outputs; when EN is high, Q retains its previous value. OE operates independently to place Y outputs in high-Z. Their interaction enables flexible control: CLR resets state, EN freezes updates, and OE isolates the bus-all without affecting internal register integrity.