Texas Instruments CY74FCT2240ATQCT

Overview

CY74FCT2240ATQCT from Texas Instruments is an octal noninverting buffer/line driver with 3-state outputs, designed for memory address, clock, and bus-transmission applications. It features 25-Ω on-chip output series resistors, I_off partial-power-down support, TTL-compatible input/output levels, 4.8 ns max propagation delay at 5 V, and operates from –40°C to 85°C.

For engineers reviewing the CY74FCT2240ATQCT datasheet, CY74FCT2240ATQCT pinout, CY74FCT2240ATQCT application, or CY74FCT2240ATQCT equivalent, this page delivers verified electrical specs, QSOP-20 package details, noise-reduction architecture, and real-world interface use cases for high-speed digital systems.

Technical Context

The CY74FCT2240ATQCT implements dual independent 4-bit noninverting buffers, each with separate active-low output-enable controls (OEA and OEB). Its edge-rate control circuitry shapes output transitions to suppress transmission-line reflections without external termination.

Each output integrates a 25-Ω series resistor and supports 3-state operation with guaranteed high-impedance isolation during power-down via I_off protection. Input thresholds meet TTL logic levels (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), and outputs drive ±12 mA sink/source under 5-V supply conditions.

Key Specifications

Pinout & Package

Package: SSOP-20 (DBQ), 0.209-inch body width, 0.65-mm lead 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 octal 3-state buffer applications.

Compared with SN74FCT2240ATSOCT and 74ACT240SCX, the CY74FCT2240ATQCT uniquely combines QSOP-20 compactness, built-in termination, and I_off protection-making it optimal for space-constrained, hot-pluggable, or reflection-sensitive industrial bus designs.

Availability

CY74FCT2240ATQCT is available at Aetrix Electronics and suitable for memory subsystems, clock distribution networks, industrial backplanes, and bus-oriented transmitter/receiver applications requiring stable component supply across extended temperature ranges.

Supply support for CY74FCT2240ATQCT 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The CY74FCT2240ATQCT belongs to TI's FCT logic family, engineered for high-speed, low-noise, TTL-compatible digital interfacing in mission-critical industrial and computing infrastructure.

FAQ

What is the maximum operating frequency supported by the CY74FCT2240ATQCT?

The CY74FCT2240ATQCT does not specify a maximum clock frequency directly, but its 4.8 ns maximum propagation delay (t_PLH/t_PHL) supports reliable operation in systems with data valid windows ≥10 ns. In practice, it is commonly used in 10–25 MHz bus applications where setup/hold timing margins and signal integrity-not raw toggle rate-are governing factors. The CY74FCT2240ATQCT is optimized for stable, low-noise data transfer rather than GHz switching.

Does the CY74FCT2240ATQCT require external pull-up or pull-down resistors on its enable inputs?

No, the CY74FCT2240ATQCT does not require external biasing on OEA or OEB. Its TTL-compatible inputs have defined thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) and low input leakage (±1 µA), allowing direct connection to microcontroller GPIOs or open-collector drivers. However, per TI's recommended operating conditions, all unused inputs-including OEA and OEB-must be tied to V_CC or GND to prevent floating states and ensure predictable 3-state behavior.

Can the CY74FCT2240ATQCT be used with a 3.3-V microcontroller interface?

The CY74FCT2240ATQCT is a 5-V-only device with TTL input thresholds and 5-V output swing; it is not 3.3-V tolerant. Direct connection to a 3.3-V microcontroller risks violating its absolute maximum input voltage rating (–0.5 V to 7 V) and may cause unreliable logic interpretation due to marginal V_IH margin. To interface with 3.3-V systems, level-shifting circuitry (e.g., TI TXB0108 or discrete MOSFET translator) is required upstream of the CY74FCT2240ATQCT inputs.

How does the 25-Ω on-chip resistor in the CY74FCT2240ATQCT improve signal integrity?

The 25-Ω on-chip series resistor in the CY74FCT2240ATQCT forms a controlled-impedance source termination that matches typical PCB trace impedances (50–75 Ω) when combined with load capacitance and trace characteristics. This significantly reduces signal reflections, overshoot, and ringing-especially on traces longer than 5 cm-without requiring eight discrete 22–33 Ω resistors. As a result, the CY74FCT2240ATQCT simplifies layout, cuts BOM cost, and improves timing margin consistency across production units.

Is the CY74FCT2240ATQCT pin-compatible with earlier CY74FCT2240T variants?

Yes, the CY74FCT2240ATQCT is functionally and pin-compatible with other members of the CY74FCT2240x family, including the CY74FCT2240T, CY74FCT2240CT, and CY74FCT2240TSOCT. All share identical pinout (QSOP-20 or SOIC-20), logic function, and terminal assignments. The "A" speed grade (4.8 ns) differs from the "T" (8 ns) and "C" (4.1 ns) variants, but timing differences do not affect pin compatibility or PCB layout reuse.