Texas Instruments CY74FCT245ATSOCT

Overview

CY74FCT245ATSOCT from Texas Instruments is an 8-bit noninverting bidirectional transceiver with 3-state outputs, designed for bus-oriented data routing between two 8-bit ports (A and B). It features 64-mA sink / 32-mA source drive strength, 4.6-ns max propagation delay (tPLH/tPHL), Ioff partial-power-down support, and TTL-compatible input/output logic levels. It is used in industrial control backplanes and legacy system bus isolation.

For engineers reviewing the CY74FCT245ATSOCT datasheet, CY74FCT245ATSOCT pinout, CY74FCT245ATSOCT application, or CY74FCT245ATSOCT equivalent, key selection criteria include 3-state bus contention control, direction-select (T/R) and output-enable (OE) timing margins, Ioff leakage under power-down, and SOIC-20 package thermal performance at 5 V supply.

Technical Context

The CY74FCT245ATSOCT implements a dual-bus transceiver architecture with independent transmit/receive (T/R) polarity control and global output enable (OE) that places both A and B ports into high-impedance when asserted high. Its edge-rate control circuitry reduces switching noise while maintaining matched rise/fall times.

It operates within a 4.75–5.25 V supply range and supports full TTL-level compatibility: VIH = 2 V min, VIL = 0.8 V max, VOH = 2.4 V min (at –32 mA), VOL = 0.55 V max (at 64 mA). The Ioff specification (±1 µA at VCC = 0 V) enables safe operation during partial power-down sequences.

Key Specifications

Pinout & Package

Package: SOIC-20 (DW), 7.5 mm × 12.8 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1 (unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74FCT245ATSOCT and 74AC245SCX, the CY74FCT245ATSOCT delivers guaranteed Ioff protection and native TTL compatibility - making it the sole choice for industrial hot-swap and legacy bus integration where reliability and drop-in replacement are mandatory.

Availability

CY74FCT245ATSOCT is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system bus isolation, and modular I/O expansion requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CY74FCT245ATSOCT 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 industrial-grade product experience.

The CY74FCT245ATSOCT belongs to the FCT logic family, engineered for high-noise-immunity, bus-oriented applications in industrial automation, telecom infrastructure, and legacy system upgrades where TTL compatibility and robust 3-state control are essential.

FAQ

What is the maximum operating frequency supported by the CY74FCT245ATSOCT?

The CY74FCT245ATSOCT does not specify a maximum clock frequency in its datasheet because it is a combinatorial transceiver, not a clocked device. However, its 4.6-ns maximum propagation delay (tPLH/tPHL) supports reliable operation in bus systems running up to 100 MHz, assuming adequate setup/hold timing margins and controlled trace impedance. System-level timing must account for worst-case delays across voltage, temperature, and load conditions - the CY74FCT245ATSOCT itself imposes no inherent frequency ceiling beyond its propagation characteristics.

Does the CY74FCT245ATSOCT support hot-swap capability?

Yes, the CY74FCT245ATSOCT supports hot-swap via its Ioff feature: when VCC = 0 V, Ioff leakage is limited to ±1 µA even with up to 4.5 V applied to I/O pins. This prevents damaging back-current flow during live insertion/removal of boards in modular systems. However, proper system-level hot-swap circuitry (e.g., slew-limited power ramp, series resistors) remains necessary - the CY74FCT245ATSOCT enables but does not fully implement hot-swap alone.

Can the CY74FCT245ATSOCT be used with 3.3-V logic systems?

No, the CY74FCT245ATSOCT is not 3.3-V compatible. It requires a 4.75–5.25 V supply and is specified only for TTL-level inputs (VIH ≥ 2 V, VIL ≤ 0.8 V) and outputs (VOH ≥ 2.4 V at –32 mA). Driving or receiving 3.3-V logic directly risks undriven inputs, marginal noise margins, or excessive current draw. For 3.3-V interfacing, use a dedicated level-shifting transceiver such as the TXB0304 or SN74AVC24T245 instead of the CY74FCT245ATSOCT.

What is the purpose of the T/R and OE pins on the CY74FCT245ATSOCT?

The T/R (transmit/receive) pin controls data direction: high enables A→B flow, low enables B→A flow. The OE (output enable) pin globally disables both ports into high-impedance when high. These two controls operate independently - for example, OE = high blocks all I/O regardless of T/R state, while OE = low allows bidirectional flow governed solely by T/R. This dual-control architecture prevents bus contention during state transitions and enables flexible bus arbitration in the CY74FCT245ATSOCT.

Is the CY74FCT245ATSOCT pin-compatible with older 74LS245 devices?

No, the CY74FCT245ATSOCT is not pin-compatible with the 74LS245. Although both are 20-pin SOIC bidirectional transceivers with identical pin numbering (A0–A7, B0–B7, T/R, OE, VCC, GND), the CY74FCT245ATSOCT has different DC and AC electrical characteristics - notably higher drive strength (64/32 mA vs. 24/15 mA), faster propagation (4.6 ns vs. 15 ns), and Ioff support absent in LS logic. While PCB layout may reuse the footprint, direct substitution requires validation of timing margins, power delivery, and signal integrity - the CY74FCT245ATSOCT is a functional upgrade, not a drop-in replacement.