Texas Instruments CY74FCT157ATSOCT

Overview

CY74FCT157ATSOCT from Texas Instruments is a quad 2-input multiplexer with 3-state outputs, designed for data routing and function generation in TTL- and FCT-compatible digital systems. It features 5 ns propagation delay (max), ±32 mA output drive, Ioff partial-power-down support, and operates across –40°C to +85°C. Used in bus multiplexing, register selection, and logic synthesis in industrial control and instrumentation.

For engineers reviewing the CY74FCT157ATSOCT datasheet, CY74FCT157ATSOCT pinout, CY74FCT157ATSOCT application, or CY74FCT157ATSOCT equivalent, key selection criteria include 3-state output timing, Ioff-enabled power-down isolation, TTL-level input compatibility, and SOIC-16 package thermal performance (θJA = 57°C/W).

Technical Context

The CY74FCT157ATSOCT implements four independent 2:1 multiplexers sharing one common select (S) and active-low enable (E) input. Each Y output reflects I0a–I0d or I1a–I1d based on S state when E is low; all outputs go high-impedance when E is high.

Its edge-rate control circuitry ensures matched rise/fall times and reduced switching noise, while Ioff protection limits backflow current during partial power-down. Input thresholds (VIH = 2 V min, VIL = 0.8 V max) and output levels (VOH = 2.4 V min at –32 mA, VOL = 0.55 V max at 64 mA) guarantee robust interoperability with TTL and FCT families.

Key Specifications

Pinout & Package

Package: SOIC-16 (DW), 10.75 mm × 10.7 mm body, 1.27 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2-input multiplexer applications.

Compared with CY74FCT157ATSOCT, CY74FCT157CTSOCT trades 1.7 ns speed for reduced IOL (32 mA → 12 mA), while SN74FCT157ATSOCT offers identical performance with enhanced supply-chain traceability and TI's extended product lifecycle support.

Availability

CY74FCT157ATSOCT is available at Aetrix Electronics and suitable for industrial bus multiplexing, register file selection, and logic function generation requiring stable component supply, long-lifecycle assurance, and RoHS-compliant SOIC packaging.

Supply support for CY74FCT157ATSOCT 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 industrial and automotive ICs.

The CY74FCT157ATSOCT belongs to TI's FCT logic family-designed for noise-immune, high-drive 5 V digital interfacing in harsh industrial environments with strict power sequencing requirements.

FAQ

What is the maximum propagation delay of the CY74FCT157ATSOCT?

The CY74FCT157ATSOCT has a maximum propagation delay of 5 ns for tPLH/tPHL (input-to-output), measured under recommended operating conditions (VCC = 4.75–5.25 V, TA = –40°C to +85°C). This applies to transitions at S, E, or data inputs (I0/I1) to corresponding Y outputs, ensuring predictable timing in synchronous 200 MHz bus systems.

Does the CY74FCT157ATSOCT support partial power-down operation?

Yes, the CY74FCT157ATSOCT includes Ioff circuitry that disables outputs and limits reverse current to ±1 µA when VCC = 0 V and outputs are biased to 4.5 V. This feature enables safe use in hot-swap backplanes and multi-rail systems where power domains sequence independently, protecting both CY74FCT157ATSOCT and downstream components.

What are the input voltage thresholds for the CY74FCT157ATSOCT?

The CY74FCT157ATSOCT specifies VIH(min) = 2.0 V and VIL(max) = 0.8 V across its operating temperature range, making it fully compatible with standard TTL logic levels. These thresholds ensure reliable recognition of high/low states from legacy 5 V TTL drivers without external biasing or level shifting.

Can the CY74FCT157ATSOCT drive multiple TTL loads directly?

Yes, the CY74FCT157ATSOCT delivers ±32 mA per output, sufficient to drive up to 10 standard TTL unit loads (each requiring 0.4 mA high / 1.6 mA low). This eliminates the need for external buffers in typical bus-interface applications, simplifying design and reducing board space and BOM cost.

Is the CY74FCT157ATSOCT pin-compatible with other FCT multiplexers?

Yes, the CY74FCT157ATSOCT is functionally and pin-compatible with CY74FCT157T-series devices including CY74FCT157CTSOCT and CY74FCT157ATSOC. Its SOIC-16 (DW) footprint, pin assignments, and logic behavior match the FCT family standard, enabling drop-in replacement without PCB or firmware modifications.