Texas Instruments CY74FCT652ATQCT

Overview

CY74FCT652ATQCT from Texas Instruments is an 8-bit registered transceiver with 3-state outputs, designed for bidirectional data routing between A and B buses in TTL/CMOS mixed-signal systems. It features independent D-type flip-flop registers per bus, real-time/stored-data multiplexing, 6.3 ns propagation delay (tPLH/tPHL), ±32 mA output drive, and Ioff support for partial-power-down operation.

For engineers reviewing the CY74FCT652ATQCT datasheet, CY74FCT652ATQCT pinout, CY74FCT652ATQCT application, or CY74FCT652ATQCT equivalent, key selection criteria include registered bus isolation timing, simultaneous clock-edge storage capability, 5 V supply compatibility, and QSOP-24 package suitability for high-density board layouts.

Technical Context

The CY74FCT652ATQCT implements dual 8-bit bidirectional transceivers with separate CPAB/CPBA clocks and SAB/SBA select controls, enabling glitch-free switching between real-time and stored-bus data paths. Its edge-rate control circuitry ensures matched rise/fall times and reduced noise coupling in high-speed digital backplanes.

Each bus side includes dedicated 3-state enable (GAB/GBA) and register clock inputs, allowing independent latching of A- or B-side data on low-to-high clock transitions - even while GAB/GBA are inactive. The device maintains full TTL input/output level compatibility and supports Ioff protection when VCC = 0 V.

Key Specifications

Pinout & Package

Package: 24-pin QSOP (DBQ), RoHS-compliant, moisture sensitivity level 2 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY74FCT652CTQCT, the CY74FCT652ATQCT trades 0.9 ns of speed for broader voltage margin tolerance; compared with SN74FCT652ATQCT, it shares identical silicon and qualification but differs only in branding and ordering channel traceability.

Availability

CY74FCT652ATQCT is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy bus extenders, and automated test fixture controllers requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for CY74FCT652ATQCT 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 for industrial, automotive, and communications markets.

The CY74FCT652ATQCT belongs to the FCT logic family, engineered for high-speed, low-noise, 5 V TTL-compatible bus interfacing in mission-critical industrial control and instrumentation systems.

FAQ

What is the maximum clock frequency supported by CY74FCT652ATQCT for reliable register storage?

CY74FCT652ATQCT does not specify a maximum clock frequency; instead, it defines minimum pulse width (6 ns) and setup/hold times (2 ns/1.5 ns). For stable operation, the maximum usable clock frequency is determined by the longest timing path - typically 1/(2 × tPLH_max) ≈ 79 MHz - assuming clean edges and proper load termination. CY74FCT652ATQCT must be used within its recommended operating conditions, including VCC = 4.75–5.25 V and TA = –40°C to +85°C.

Does CY74FCT652ATQCT support hot-swap or live-insertion in powered-backplane systems?

Yes, CY74FCT652ATQCT supports partial-power-down operation via its Ioff circuitry, which disables outputs and blocks reverse current flow when VCC = 0 V. This allows safe insertion into live 5 V backplanes, provided that all I/O pins are within –0.5 V to 7 V absolute maximum ratings and that GND is established before VCC. CY74FCT652ATQCT is explicitly characterized for this use case in TI's production data sheet.

Can CY74FCT652ATQCT operate with mixed 3.3 V and 5 V logic interfaces?

CY74FCT652ATQCT is a 5 V-only device with TTL-compatible inputs (VIH = 2.0 V min, VIL = 0.8 V max) and CMOS-like outputs (VOH ≈ 3.3 V typ at –32 mA). It accepts 3.3 V logic highs directly but requires level translation for 3.3 V outputs driving its inputs, due to its 5 V VCC dependency and lack of dual-supply operation. CY74FCT652ATQCT is not rated for 3.3 V supply operation.

How does the real-time vs. stored-data transfer mode work in CY74FCT652ATQCT?

In CY74FCT652ATQCT, SAB/SBA inputs determine data source: low selects real-time (direct pass-through), high selects stored (registered) data. When both GAB and GBA are enabled simultaneously in real-time mode, outputs reinforce inputs - holding bus states even when other drivers go high-Z. CY74FCT652ATQCT uses dedicated control logic to eliminate glitches during mode transitions, unlike discrete mux+register implementations.

Is CY74FCT652ATQCT pin-compatible with earlier CY74FCT652T variants?

Yes, CY74FCT652ATQCT is fully pin-compatible with all CY74FCT652x variants in the same package (QSOP-24), including CY74FCT652T, CY74FCT652CTQCT, and CY74FCT652TQCT. All share identical pin functions, electrical specifications, and timing architecture - differing only in propagation delay grade (6.3 ns vs. 5.4 ns vs. 9 ns) and top-side marking (FCT652A vs. FCT652C vs. FCT652).