Texas Instruments CY74FCT244DTQCT

Overview

CY74FCT244DTQCT from Texas Instruments is an octal 3-state buffer/line driver designed for memory address, clock, and bus transceiver applications in TTL- and CMOS-compatible systems. It delivers 3.6 ns propagation delay (max), 64 mA sink / 32 mA source output drive, Ioff partial-power-down support, edge-rate control for noise reduction, and operates from 4.75 V to 5.25 V.

For engineers reviewing the CY74FCT244DTQCT datasheet, CY74FCT244DTQCT pinout, CY74FCT244DTQCT application, or CY74FCT244DTQCT equivalent, this page provides verified functional specifications, package mapping to QSOP-20, real-world timing behavior, Ioff-enabled power-down operation, and direct TTL/CMOS interface capability without level-shifting components.

Technical Context

The CY74FCT244DTQCT implements dual 4-bit noninverting buffers with independent 3-state enable controls (OEA and OEB), supporting bidirectional bus isolation. Its FCT-family architecture ensures TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and CMOS-level output swing (VOH = 2.4 V min at –32 mA, VOL = 0.3 V max at 64 mA).

Edge-rate control circuitry limits slew rate to suppress simultaneous switching noise, while the Ioff feature disables outputs and limits leakage to ±1 µA when VCC = 0 V - enabling safe back-drive prevention during partial power-down in mixed-voltage systems.

Key Specifications

Pinout & Package

Package: QSOP-20 (DBQ), 0.15 mm pitch, 4.4 mm width, 7.2 mm length, 1.75 mm height - optimized for high-density PCB layouts with improved thermal resistance (θJA = 68°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state buffer applications.

Compared with SN74FCT244N and 74ACT244SCX, the CY74FCT244DTQCT offers superior speed (3.6 ns vs. ≥4.1 ns), higher drive (64 mA vs. ≤48 mA), and unique system-level features - Ioff for safe power sequencing and edge-rate control for EMI reduction - making it optimal for modern 5-V bus interfaces demanding reliability and signal fidelity.

Availability

CY74FCT244DTQCT is available at Aetrix Electronics and suitable for memory address buffering, clock distribution, and parallel bus transceiver applications requiring stable component supply, long-term industrial availability, and RoHS-compliant packaging.

Supply support for CY74FCT244DTQCT 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 over 50 years of innovation in high-reliability interface ICs.

The CY74FCT244DTQCT belongs to TI's FCT logic family, engineered for high-speed, low-noise 5-V digital interfacing in industrial, computing, and communications equipment where signal integrity and power sequencing robustness are critical.

FAQ

What is the maximum operating frequency supported by the CY74FCT244DTQCT?

The CY74FCT244DTQCT does not specify a maximum clock frequency in its datasheet, but its 3.6 ns maximum propagation delay (tPLH/tPHL) supports reliable operation in systems with data rates up to approximately 270 MHz under ideal loading conditions. Real-world usable frequency depends on bus capacitance, termination, and layout - for 50-pF loads, sustained operation above 100 MHz is achievable with proper design practices.

Does the CY74FCT244DTQCT support partial power-down mode?

Yes, the CY74FCT244DTQCT supports partial power-down mode via its Ioff feature. When VCC = 0 V, the outputs enter a high-impedance state with leakage limited to ±1 µA, preventing damaging current backflow from live bus lines into the unpowered device - essential for hot-plug and mixed-rail system architectures.

Can the CY74FCT244DTQCT interface directly with 3.3-V logic inputs?

No, the CY74FCT244DTQCT is a 5-V-only device with TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max). While 3.3-V logic high outputs may exceed VIH in some cases, they lack guaranteed noise margin and violate recommended operating conditions. A level-shifter or 3.3-V–tolerant buffer such as the TXB0108 is required for reliable 3.3-V to 5-V interfacing.

What is the thermal resistance (θJA) of the CY74FCT244DTQCT in its QSOP-20 package?

The CY74FCT244DTQCT in QSOP-20 (DBQ) package has a junction-to-ambient thermal resistance (θJA) of 68°C/W, as specified in the Texas Instruments datasheet SCCS071. This value assumes standard JEDEC 2-layer board conditions; actual performance improves with enhanced copper pour and thermal vias.

How are the enable pins OEA and OEB used in practical circuit design?

OEA and OEB are independent active-low 3-state enables for Group A (OA0–OA3) and Group B (OB0–OB3). In practice, they are tied to system control signals - e.g., OEA to address-enable and OEB to data-enable - allowing selective activation of bus segments. Both must be low for outputs to drive; either high places its group in high-Z, enabling bidirectional bus arbitration without external logic.