Texas Instruments CY74FCT543CTQCT

Overview

CY74FCT543CTQCT from Texas Instruments is an 8-bit latched registered transceiver with 3-state outputs, designed for bidirectional data flow control in TTL- and FCT-compatible bus systems. It features independent A-to-B and B-to-A latch-enable (LEAB/LEBA) and output-enable (OEAB/OEBA) controls, 5.3 ns max propagation delay, 64 mA sink / 32 mA source drive strength, and Ioff support for partial-power-down operation in industrial backplane and memory interface applications.

For engineers reviewing the CY74FCT543CTQCT datasheet, CY74FCT543CTQCT pinout, CY74FCT543CTQCT application, or CY74FCT543CTQCT equivalent, key selection considerations include its QSOP-24 package, 4.75–5.25 V supply range, matched rise/fall times, edge-rate controlled noise immunity, and dual-latch architecture enabling simultaneous storage and direction-controlled buffering.

Technical Context

The CY74FCT543CTQCT implements two independent 8-bit latch banks-A-to-B and B-to-A-each with dedicated enable inputs (CEAB/CEBA), latch-enable inputs (LEAB/LEBA), and output-enable inputs (OEAB/OEBA). Its dual-latch structure allows transparent capture followed by storage on LEAB/LEBA low-to-high transitions, while 3-state outputs are activated only when both CE and OE are low.

It integrates Ioff circuitry to disable outputs during power-down, preventing backflow current, and uses edge-rate control to reduce switching noise. Fully compatible with TTL input thresholds (VIH = 2 V, VIL = 0.8 V) and FCT logic levels, it operates across –40°C to +85°C with 5.3 ns max tPLH/tPHL at VCC = 5 V.

Key Specifications

Pinout & Package

QSOP-24 (DBQ) package: 3.9 mm × 8.7 mm body, 0.635 mm pitch, gull-wing leads, moisture sensitivity level 2. Thermal resistance θJA = 61°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY74FCT543CTQCT, the CY74FCT543ATQCT trades 1.2 ns of speed for lower cost, while SN74FCT543CTSOCT offers identical performance in a larger SOIC package-enabling layout flexibility without functional compromise.

Availability

CY74FCT543CTQCT is available at Aetrix Electronics and suitable for industrial backplane routing, FPGA memory interfacing, legacy bus extension, and automated test equipment requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for CY74FCT543CTQCT 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 5 V logic families including FCT, ABT, and LVT.

The CY74FCT543CTQCT belongs to TI's military- and industrial-grade FCT logic family, engineered for robust noise immunity, precise timing control, and seamless interoperability with legacy TTL systems in mission-critical infrastructure.

FAQ

What is the maximum operating frequency supported by CY74FCT543CTQCT?

CY74FCT543CTQCT does not specify a maximum clock frequency but delivers 5.3 ns typical propagation delay (tPLH/tPHL), supporting reliable operation in systems with setup/hold timing budgets down to ~100 MHz effective data rates. Its 2 ns minimum pulse width (tw) on LEAB/LEBA and 2 ns setup/hold times enable use with fast microcontroller buses and FPGA I/O interfaces. Actual system frequency depends on board layout, load capacitance, and timing margins.

Does CY74FCT543CTQCT support hot-swap or partial-power-down operation?

Yes, CY74FCT543CTQCT includes Ioff circuitry that actively disables outputs when VCC = 0 V, preventing damaging current backflow from live bus lines into unpowered circuit sections. This makes CY74FCT543CTQCT suitable for hot-pluggable modules, modular backplanes, and systems requiring graceful power sequencing-provided all unused inputs are tied to VCC or GND per datasheet recommendations.

What are the key differences between CY74FCT543CTQCT and CY74FCT543ATQCT?

CY74FCT543CTQCT and CY74FCT543ATQCT share identical pinout, package (QSOP-24), drive strength (64 mA sink / 32 mA source), and feature set-including Ioff, edge-rate control, and TTL compatibility. The sole difference is speed grade: CY74FCT543CTQCT guarantees ≤5.3 ns max propagation delay, while CY74FCT543ATQCT is rated ≤6.5 ns. Both operate over –40°C to +85°C.

Can CY74FCT543CTQCT be used with 3.3 V logic systems?

No-CY74FCT543CTQCT is a 5 V-only device with recommended VCC = 4.75–5.25 V and TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max). It lacks 3.3 V tolerance and will not reliably interface with 3.3 V CMOS or LVT logic without level translation. For mixed-voltage systems, use dedicated level translators or select TI's ALVC or AUC families instead of CY74FCT543CTQCT.

Is there a drop-in replacement for CY74FCT543CTQCT in SOIC package?

Yes-CY74FCT543CTSOCT is a pin-compatible, functionally identical variant in SOIC-24 package, with matching 5.3 ns speed grade, drive strength, and electrical specifications. It differs only in package dimensions (SOIC vs. QSOP), thermal resistance (46°C/W vs. 61°C/W), and reel packaging (2000 pcs vs. 2500 pcs). No PCB redesign is needed beyond footprint adaptation.