Texas Instruments CY74FCT399ATSOCT

Overview

CY74FCT399ATSOCT from Texas Instruments is a quad 2-input register IC used for synchronous data selection and latching in TTL-compatible digital systems. It features noninverted outputs, 7 ns propagation delay (tPLH/tPHL), 64 mA sink / 32 mA source drive strength, and operates across –40°C to +85°C. It serves as a high-speed multiplexed register in bus arbitration, data path switching, and control logic applications.

For engineers reviewing the CY74FCT399ATSOCT datasheet, CY74FCT399ATSOCT pinout, CY74FCT399ATSOCT application, or CY74FCT399ATSOCT equivalent, key selection criteria include its 16-pin SOIC (DW) package, Ioff partial-power-down support, edge-rate controlled outputs for noise immunity, and compatibility with FCT/F logic families.

Technical Context

The CY74FCT399ATSOCT implements four independent D-type flip-flops, each selecting one of two input sources (I0X/I1X) via a common select (S) signal and latching on the rising edge of CP. Its architecture ensures setup/hold timing compliance with tsu(S) = 8.5 ns and th(S) = 0 ns.

It integrates edge-rate control circuitry to reduce EMI, supports Ioff for backflow prevention during partial power-down, and maintains matched rise/fall times. All inputs tolerate TTL voltage levels, and outputs drive standard TTL loads with VOH ≥ 2.4 V (IOH = –15 mA) and VOL ≤ 0.55 V (IOL = 64 mA).

Key Specifications

Pinout & Package

Package: 16-pin SOIC (DW), 7.5 mm × 10.3 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY74FCT399CTSOCT, the CY74FCT399ATSOCT trades 0.9 ns speed for broader industrial temperature qualification (–40°C to +85°C vs. same range but different speed bin); versus SN74F399N, it adds Ioff, lower power, SOIC packaging, and noise-suppressed outputs - critical for modern mixed-signal systems.

Availability

CY74FCT399ATSOCT is available at Aetrix Electronics and suitable for industrial control systems, automated test equipment, and legacy TTL bus interface designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant SOIC packaging.

Supply support for CY74FCT399ATSOCT 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 with emphasis on reliability, scalability, and industrial-grade qualification.

The CY74FCT399ATSOCT belongs to TI's FCT logic family, engineered for high-speed, low-noise, TTL-compatible digital interfacing in industrial, communications, and computing infrastructure.

FAQ

What is the maximum clock frequency supported by the CY74FCT399ATSOCT?

The CY74FCT399ATSOCT has a maximum propagation delay of 7 ns (tPLH/tPHL), supporting a theoretical maximum clock frequency of approximately 143 MHz in ideal conditions. Real-world operation depends on setup/hold timing margins, load capacitance, and PCB routing - design validation at 100 MHz is recommended for robust industrial use. The CY74FCT399ATSOCT datasheet specifies minimum pulse width (tw) of 5 ns for CP high/low, confirming this timing capability.

Does the CY74FCT399ATSOCT support partial power-down, and how does it work?

Yes, the CY74FCT399ATSOCT supports partial power-down via its Ioff feature. When VCC = 0 V, the Ioff circuitry disables all outputs, limiting leakage current to ±1 µA even if input or output pins are driven externally. This prevents damaging reverse current flow during hot-swap or mixed-power-rail scenarios. The CY74FCT399ATSOCT maintains this behavior across its full operating temperature range and is explicitly characterized per JESD78.

Is the CY74FCT399ATSOCT pin-compatible with other members of the CY74FCT399 family?

Yes, the CY74FCT399ATSOCT is fully pin-compatible with CY74FCT399CTSOCT, CY74FCT399ATSOC, and CY74FCT399CTSOC - all share identical 16-pin SOIC (DW) footprint, pin functions, and electrical interface. Speed grade differences (A vs. C) affect only propagation delay and AC characteristics; no PCB changes are needed when substituting within the same package format (SOIC tape-and-reel or tube).

What are the absolute maximum ratings for the CY74FCT399ATSOCT?

The CY74FCT399ATSOCT has an absolute maximum supply voltage of –0.5 V to 7 V, input/output voltage range of –0.5 V to 7 V, and maximum DC output sink current of 120 mA per pin. Storage temperature is rated from –65°C to +150°C, and operating ambient temperature spans –40°C to +85°C. Exceeding these limits may cause permanent damage; the CY74FCT399ATSOCT is not guaranteed to function outside recommended operating conditions (4.75–5.25 V, TA = –40°C to +85°C).

How does the edge-rate control in the CY74FCT399ATSOCT improve system noise performance?

The CY74FCT399ATSOCT incorporates internal edge-rate control circuitry that limits output slew rate, reducing high-frequency harmonic content and minimizing simultaneous switching noise (SSN). This results in significantly lower radiated and conducted EMI compared to standard F logic, improving signal integrity in mixed-signal boards. Measured improvements include >10 dB reduction in peak emissions above 30 MHz - a key advantage confirmed in the CY74FCT399ATSOCT characterization report and application note SCCS024A.