Texas Instruments CY74FCT2543ATSOCT

Overview

CY74FCT2543ATSOCT from Texas Instruments is an octal latched transceiver with independent A-to-B and B-to-A data paths, 3-state outputs, edge-rate control, 25-Ω output series resistors, and I_off support for partial-power-down operation. It operates at 4.75–5.25 V, delivers ±12 mA/±15 mA drive strength, and achieves 6.5 ns max propagation delay across –40°C to +85°C. Used in bidirectional bus isolation and level translation between TTL-compatible subsystems.

For engineers reviewing the CY74FCT2543ATSOCT datasheet, CY74FCT2543ATSOCT pinout, CY74FCT2543ATSOCT application, or CY74FCT2543ATSOCT equivalent, key selection criteria include latch-enable timing (2 ns setup/hold), 3-state enable/disable times (≤9 ns), matched rise/fall times, and SOIC-24 package compatibility with legacy FCT logic designs.

Technical Context

This device integrates two independent 8-bit D-type latch sets - one for A-to-B and one for B-to-A data flow - each controlled by dedicated latch-enable (LEAB/LEBA) and output-enable (OEAB/OEBA) inputs. Directional control is further refined via separate CEAB and CEBA enable inputs that gate data entry into respective latches.

On-die 25-Ω series termination resistors suppress transmission-line reflections, while edge-rate control circuitry ensures clean signal transitions without overshoot. The I_off feature disables outputs when V_CC = 0 V, limiting backflow current to ±1 µA and enabling safe partial-power-down in mixed-voltage systems.

Key Specifications

Pinout & Package

Package: SOIC-24 (DW), 7.5 mm × 15.4 mm body, 1.27 mm lead pitch, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY74FCT2543CTSOCT, the CY74FCT2543ATSOCT trades 1 ns of propagation delay for improved noise immunity and lower dynamic power; versus SN74FCT2543ATSOCT, it is the same silicon die with identical timing, drive, and thermal behavior - differing only in prefix branding.

Availability

CY74FCT2543ATSOCT is available at Aetrix Electronics and suitable for industrial backplane interfaces, PCI expansion modules, memory bus buffers, and TTL-to-microcontroller bridging requiring stable component supply and long-term lifecycle support.

Supply support for CY74FCT2543ATSOCT 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 development.

The CY74FCT2543ATSOCT belongs to the 74FCT family of advanced CMOS logic devices designed specifically for noise-sensitive, high-density 5-V digital systems requiring TTL compatibility and robust bus interfacing.

FAQ

What is the maximum operating temperature range for CY74FCT2543ATSOCT?

The CY74FCT2543ATSOCT is rated for continuous operation from –40°C to +85°C ambient temperature. This range is validated per JEDEC JESD78 and applies to all electrical specifications including propagation delay, drive strength, and I_off performance. Thermal derating is not required within this envelope, and the SOIC-24 package exhibits 46°C/W θ_JA under standard JEDEC test conditions.

Does CY74FCT2543ATSOCT support true bidirectional data flow without external control logic?

Yes, CY74FCT2543ATSOCT supports fully independent bidirectional data flow using its dual-latch architecture. CEAB and CEBA enable inputs gate data entry into respective A or B latches, while OEAB and OEBA separately control 3-state output drivers. This allows concurrent A→B latching and B→A output driving - no external logic is needed to coordinate direction or timing.

Can CY74FCT2543ATSOCT replace CY74FCT543T in existing designs?

Yes, CY74FCT2543ATSOCT is explicitly documented as a drop-in replacement for CY74FCT543T to reduce noise in existing designs. Both share identical pinout, function table, and SOIC-24 package. The CY74FCT2543ATSOCT adds edge-rate control and on-die 25-Ω termination - enhancements that improve signal integrity without requiring layout changes.

What is the purpose of the CEAB and CEBA pins on CY74FCT2543ATSOCT?

The CEAB (A-to-B Enable) and CEBA (B-to-A Enable) pins on CY74FCT2543ATSOCT act as directional gate controls: CEAB must be low to load data from A inputs into the A latches or enable B outputs; CEBA must be low for B-to-A operation. They decouple data entry timing from latch strobing, enabling precise control of bus arbitration and handshake protocols.

Is CY74FCT2543ATSOCT compatible with 3.3-V logic inputs?

No, CY74FCT2543ATSOCT is not 3.3-V input-tolerant. Its input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) and recommended V_CC range (4.75–5.25 V) are optimized for TTL and 5-V CMOS systems. Driving it directly from 3.3-V logic may result in marginal or non-compliant switching; level-shifting circuitry is required for reliable interoperability.