Texas Instruments CY74FCT2646ATQCT

Overview

CY74FCT2646ATQCT from Texas Instruments is an 8-bit registered transceiver with 3-state outputs, dual independent registers (A and B), edge-rate control, 25-Ω output series resistors, and I_off support for partial-power-down operation. It operates at 5 V, delivers ±15 mA drive strength, and enables bidirectional data multiplexing in bus-isolation and real-time transfer applications.

For engineers reviewing the CY74FCT2646ATQCT datasheet, CY74FCT2646ATQCT pinout, CY74FCT2646ATQCT application, or CY74FCT2646ATQCT equivalent, key selection criteria include its 6.3 ns propagation delay (max), QSOP-24 package, TTL-compatible I/O levels, register-controlled data storage, and integrated output termination for reflection-noise suppression in high-speed digital backplanes.

Technical Context

The CY74FCT2646ATQCT implements two independent 8-bit D-type flip-flop registers-one per bus-with separate clock inputs (CPAB, CPBA) and select controls (SAB, SBA) enabling multiplexed sourcing of stored vs. transparent data. Its 3-state outputs are managed by G (output enable) and DIR (direction control), supporting isolation, real-time transfer, and stored-data transfer modes.

Edge-rate control circuitry and on-die 25-Ω series resistors reduce transmission-line reflections without external components. The I_off feature disables outputs when V_CC = 0 V, preventing backflow current during partial power-down-critical for hot-swap and mixed-voltage system designs.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY74FCT2646CTQCT, the CY74FCT2646ATQCT trades 0.9 ns of propagation delay for broader voltage tolerance margin and identical noise-suppression features; versus SN74FCT2646ATQCTG4, it shares identical silicon and timing but differs only in packaging logistics and marking-making both viable drop-in alternatives depending on supply chain constraints.

Availability

CY74FCT2646ATQCT is available at Aetrix Electronics and suitable for industrial backplane isolation, legacy system data multiplexing, high-speed test equipment, PLC I/O expansion, and embedded bus arbitration requiring stable component supply and long-term lifecycle support.

Supply support for CY74FCT2646ATQCT 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.

The CY74FCT2646ATQCT belongs to TI's FCT logic family, designed specifically for noise-immune, high-speed bus interfacing in industrial, telecom, and computing systems where TTL compatibility, low skew, and robust ESD performance are mandatory.

FAQ

What is the maximum propagation delay of the CY74FCT2646ATQCT?

The CY74FCT2646ATQCT has a maximum propagation delay (t_PD) of 6.3 ns under recommended operating conditions (V_CC = 4.75 V to 5.25 V, T_A = –40°C to +85°C). This value applies to A↔B or B↔A data paths and is measured from clock or control input to output transition, ensuring predictable timing in synchronous bus systems. The CY74FCT2646ATQCT meets this spec across its full industrial temperature range without derating.

Does the CY74FCT2646ATQCT support partial-power-down operation?

Yes, the CY74FCT2646ATQCT supports partial-power-down operation via its I_off circuitry. When V_CC = 0 V, the outputs are disabled and leakage current is limited to ±1 µA, preventing damaging backflow current from live buses into the unpowered device. This feature is explicitly verified in the datasheet and enables safe use in hot-swap backplanes and mixed-power-domain systems where the CY74FCT2646ATQCT may be powered independently of connected buses.

What package type and footprint does the CY74FCT2646ATQCT use?

The CY74FCT2646ATQCT uses a QSOP-24 (DBQ) package: 24-pin, 3.9 mm × 8.7 mm body size, 0.635 mm lead pitch, with gull-wing leads and RoHS-compliant CU-NiPdAu surface finish. Its MSL rating is Level-2-260°C-1 year, and it ships in tape-and-reel format (2500 units per reel). The pinout matches industry-standard 24-pin QSOP layouts, allowing direct placement in existing designs qualified for FCT-family transceivers.

How does the CY74FCT2646ATQCT handle bus noise and signal integrity?

The CY74FCT2646ATQCT improves bus noise immunity through three integrated features: (1) edge-rate control circuitry that limits slew rate without compromising speed; (2) 25-Ω on-die series output resistors that dampen transmission-line reflections; and (3) matched rise/fall times that minimize ground bounce and crosstalk. These features collectively reduce EMI, overshoot, and timing jitter-verified by TI's characterization across temperature and voltage ranges-and allow the CY74FCT2646ATQCT to replace older transceivers like CY74FCT646T without adding external termination.

Can the CY74FCT2646ATQCT be used in place of the CY74FCT2646CTQCT?

Yes, the CY74FCT2646ATQCT is functionally and pin-compatible with the CY74FCT2646CTQCT, differing only in maximum propagation delay (6.3 ns vs. 5.4 ns) and minor process variations. Both share identical pinout, register architecture, I/O voltage levels, drive strength, and thermal characteristics. The CY74FCT2646ATQCT may be substituted where timing裕度 allows; however, designs requiring the tightest possible t_PD should retain the 'C' speed grade. No PCB or firmware changes are needed for either part.