Texas Instruments SN74F543NT

Overview

SN74F543NT from Texas Instruments is an octal registered transceiver with dual-direction 3-state outputs, featuring independent A-to-B and B-to-A latch-enable (LEAB/LEBA) and output-enable (OEAB/OEBA) controls, 24 mA A-side sink capability, 64 mA B-side sink capability, and operation across 0°C to 70°C - used in bidirectional data bus isolation and temporary storage in TTL-based industrial control backplanes.

For engineers reviewing the SN74F543NT datasheet, SN74F543NT pinout, SN74F543NT application, or SN74F543NT equivalent, this page delivers verified functional architecture, timing constraints (tPLH/tPHL ≤ 12.5 ns), absolute maximum ratings (VCC up to 7 V), package-specific thermal and reflow data (NT = PDIP-24), and direct alternative part comparisons for legacy system redesign and obsolescence mitigation.

Technical Context

The SN74F543NT implements two independent sets of D-type latches - one for A-to-B flow (controlled by CEAB, LEAB, OEAB) and one for B-to-A flow (CEBA, LEBA, OEBA) - enabling simultaneous bidirectional data staging without contention. Its 3-state outputs support bus-sharing via separate enable logic per direction.

It operates strictly within TTL voltage thresholds (VIH = 2 V min, VIL = 0.8 V max at VCC = 5 V), exhibits propagation delays as low as 2.2 ns (tPLH/tPHL), and supports short-circuit output currents up to –225 mA (B-side) under defined test conditions - all validated for 0°C to 70°C free-air operation.

Key Specifications

Pinout & Package

SN74F543NT uses a 24-pin plastic DIP (300-mil) package (NT suffix), with 0.3-inch body width, through-hole mounting, and industry-standard pin spacing compatible with legacy PCB layouts and socketed prototyping.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F543NT, SN74F541N lacks reverse-path latching and control, limiting it to unidirectional use; SN74F540N preserves pin compatibility but inverts logic states - both require schematic and timing validation before substitution in bidirectional bus architectures.

Availability

SN74F543NT is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy CPU bus isolation, test equipment data capture, and programmable logic controller I/O expansion requiring stable component supply and long-term obsolescence support.

Supply support for SN74F543NT 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and communications portfolio coverage.

The SN74F543NT belongs to TI's 74F Fast TTL logic family, designed specifically for high-speed, low-latency data routing in commercial-grade computing and control systems operating at 5 V.

FAQ

What is the function of the CEAB and CEBA pins on the SN74F543NT?

The CEAB pin enables the A-to-B data path: it must be low to sample A inputs or drive B outputs. Similarly, CEBA enables the B-to-A path. Both act as chip-select gates - if either is high, its associated latch and output drivers are disabled regardless of LE or OE states. This prevents unintended data flow during partial enable sequences in the SN74F543NT.

Can the SN74F543NT operate at 3.3 V?

No - the SN74F543NT is specified only for 4.5 V to 5.5 V supply operation and requires TTL-compatible input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V). At 3.3 V, VIH exceeds 60% of VCC, violating input logic thresholds and risking unreliable switching. It is not 3.3 V tolerant and must be used in 5 V systems or with level translation for mixed-voltage designs involving SN74F543NT.

What does the "NT" suffix indicate in SN74F543NT?

The "NT" suffix denotes a 24-pin plastic dual in-line package (PDIP) with 300-mil width, through-hole mounting, and industry-standard pin pitch (0.1 inch). It is distinct from SSOP (DB) and SOIC (DW) variants and ensures mechanical and soldering compatibility with legacy sockets, wave-solder fixtures, and manual prototyping workflows using the SN74F543NT.

How does the SN74F543NT handle simultaneous A-to-B and B-to-A data transfers?

The SN74F543NT supports concurrent A-to-B and B-to-A transfers via independent control: CEAB/LEAB/OEAB manage A→B latching and output, while CEBA/LEBA/OEBA manage B→A. No internal conflict occurs because each path has dedicated registers and 3-state drivers - enabling full-duplex staging in systems like memory-mapped I/O where read and write operations overlap, as implemented in the SN74F543NT.

Is the SN74F543NT RoHS compliant?

Yes - the SN74F543NT meets RoHS Directive 2011/65/EU requirements. TI's packaging documentation confirms lead finish as NIPDAU (nickel/palladium/gold) and RoHS status as "Yes" for all active NT-suffix variants. This applies to both new production and legacy stock held by authorized distributors supplying the SN74F543NT.