Texas Instruments CY74FCT2240TSOCT

Overview

CY74FCT2240TSOCT from Texas Instruments is an octal 3-state buffer/line driver with integrated 25-Ω output series resistors, TTL-compatible input/output levels, 8 ns max propagation delay, ±15 mA output drive, and Ioff support for partial-power-down operation. It serves as a memory address driver, clock driver, or bus transmitter/receiver in industrial control and embedded systems.

For engineers reviewing the CY74FCT2240TSOCT datasheet, CY74FCT2240TSOCT pinout, CY74FCT2240TSOCT application, or CY74FCT2240TSOCT equivalent, key selection criteria include 3-state control timing (tPZH/tPLZ ≤ 9.5 ns), on-die termination for reflection suppression, Ioff-enabled backflow protection during power sequencing, and SOIC-20 compatibility with legacy FCT logic families.

Technical Context

This device 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 reduce EMI and transmission-line ringing without external components.

The 25-Ω on-chip series resistors are placed between internal output transistors and pins, enabling direct connection to 50-Ω PCB traces while maintaining TTL-level VOH ≥ 2.4 V and VOL ≤ 0.55 V at full load. Ioff functionality ensures outputs enter high-impedance state when VCC = 0 V, preventing current backflow during hot-insertion or partial system shutdown.

Key Specifications

Pinout & Package

Package: SOIC-20 (SO) with 0.300-inch body width, RoHS-compliant NiPdAu lead finish, MSL Level-2-260°C-1 year rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74FCT240NSR and 74ACT240SCX, CY74FCT2240TSOCT uniquely combines on-die 25-Ω termination, Ioff protection, and industrial temperature range in a drop-in SOIC-20 package-reducing BOM count and improving system robustness during power sequencing.

Availability

CY74FCT2240TSOCT is available at Aetrix Electronics and suitable for industrial automation, test equipment, and legacy system upgrades requiring stable component supply, long-lifecycle support, and guaranteed SOIC-20 packaging.

Supply support for CY74FCT2240TSOCT 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 company headquartered in Dallas, Texas, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

CY74FCT2240TSOCT belongs to TI's FCT logic family, engineered for high-speed, low-noise 5-V TTL-compatible interfacing with integrated signal integrity features like on-die termination and Ioff.

FAQ

What is the maximum operating frequency supported by CY74FCT2240TSOCT in a bus application?

CY74FCT2240TSOCT supports reliable operation up to 125 MHz in well-terminated 50-Ω environments, based on its 8 ns maximum propagation delay and controlled edge-rate design. Real-world bus timing must account for trace length, loading, and enable signal skew; for 25-MHz clock distribution or 10-MHz address/data buses, CY74FCT2240TSOCT provides ample timing margin and noise immunity without additional termination components.

Does CY74FCT2240TSOCT require external pull-up or pull-down resistors on its control inputs?

No, CY74FCT2240TSOCT does not require external pull-up or pull-down resistors on OEA or OEB inputs. Its TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and low input leakage (±1 µA) allow direct connection to microcontroller GPIOs or other logic outputs. However, per TI's recommended operating conditions, all unused inputs must be tied to VCC or GND to prevent floating states and ensure predictable 3-state behavior.

How does the 25-Ω on-die resistor in CY74FCT2240TSOCT improve signal integrity?

The 25-Ω on-die resistor in CY74FCT2240TSOCT is placed in series with each output driver, forming a source-termination network with typical 50-Ω PCB traces. This reduces signal reflections caused by impedance mismatches at the driver end, suppressing ringing and overshoot. Measured results show >90% reduction in reflected energy compared to unterminated drivers, enabling cleaner edges and improved timing margins in high-speed digital interconnects without adding discrete components.

Can CY74FCT2240TSOCT be used in mixed-voltage systems where VCC = 3.3 V?

No, CY74FCT2240TSOCT is specified only for 4.75 V to 5.25 V operation and must not be operated at 3.3 V. Its TTL-compatible input thresholds, output drive strength, and internal logic thresholds are designed for 5-V rail operation. Attempting to run CY74FCT2240TSOCT at 3.3 V will result in undefined logic states, insufficient VOH, and potential latch-up. For 3.3-V systems, TI recommends the LVC or AHC logic families instead.

What is the thermal performance of CY74FCT2240TSOCT in SOIC-20 package under full-load conditions?

CY74FCT2240TSOCT in SOIC-20 has a junction-to-ambient thermal resistance (θJA) of 58°C/W. Under worst-case conditions-VCC = 5.25 V, all eight outputs sinking 12 mA each, and ambient temperature at 85°C-the estimated junction temperature reaches ~115°C, remaining within the absolute maximum rating of 135°C. Adequate PCB copper area (≥1 in² per side) and moderate airflow ensure reliable long-term operation without derating.