Texas Instruments SN74F543DWE4

Overview

SN74F543DWE4 from Texas Instruments is an octal registered transceiver with 3-state outputs, implementing dual-directional data flow control via independent A-to-B and B-to-A latch-enable and output-enable inputs. It features A-side outputs rated for 24 mA sink current and B-side outputs rated for 64 mA sink current, operates over 0°C to 70°C, and supports TTL-compatible logic levels (V_IL = 0.8 V, V_IH = 2.0 V) at 4.5–5.5 V supply. It is used in bidirectional bus interface applications such as memory expansion and microprocessor system data buses.

For engineers reviewing the SN74F543DWE4 datasheet, SN74F543DWE4 pinout, SN74F543DWE4 application, or SN74F543DWE4 equivalent, key selection considerations include its dual-latch architecture, asymmetric output drive strength (A: 24 mA / B: 64 mA), 3-state output control per direction, timing parameters (t_PLH/t_PHL ≤ 12.5 ns), and SOIC-24 package compatibility with legacy TTL systems.

Technical Context

The SN74F543DWE4 implements two independent sets of D-type latches-one for A-to-B and one for B-to-A data paths-each controlled by dedicated CE, LE, and OE inputs. Its back-to-back register structure enables simultaneous storage and direction-selective output gating without bus contention.

It uses standard TTL input thresholds and delivers guaranteed low-level output voltages (V_OL ≤ 0.55 V at I_OL = 64 mA on B-side) and high-level output voltages (V_OH ≥ 2.0 V at I_OH = –15 mA on B-side), ensuring robust noise margins in mixed-logic environments.

Key Specifications

Pinout & Package

SN74F543DWE4 is packaged in a 24-pin SOIC (DW) body measuring 15.4 mm × 7.5 mm with 1.27 mm pitch, compliant with JEDEC MS-013 and RoHS standards. The package supports surface-mount reflow (MSL Level-1, 260°C peak).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F543DWE4, SN74F245N omits latching and reduces drive asymmetry, making it unsuitable for registered bus interfaces; SN74ACT543DW improves speed and power but sacrifices native TTL input threshold matching, requiring level-shifting in mixed-technology systems.

Availability

SN74F543DWE4 is available at Aetrix Electronics and suitable for memory expansion interfaces, microprocessor system buses, legacy TTL upgrades, and industrial I/O modules requiring stable component supply and long-term obsolescence management.

Supply support for SN74F543DWE4 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 solutions for industrial, automotive, and communications markets.

The SN74F logic family was designed for high-speed TTL-compatible digital systems requiring robust noise immunity, predictable timing, and interoperability with legacy 5 V logic infrastructure.

FAQ

What is the maximum sink current supported by the B-side outputs of SN74F543DWE4?

The B-side outputs (B1–B8) of SN74F543DWE4 are characterized to sink up to 64 mA each under recommended operating conditions (V_CC = 4.5 V, T_A = 25°C). This rating ensures reliable drive into multiple TTL inputs or moderate-capacitance PCB traces without external buffering. Exceeding this current risks exceeding absolute maximum ratings and may degrade output voltage compliance.

Does SN74F543DWE4 support true bidirectional data flow with independent control?

Yes, SN74F543DWE4 supports true independent bidirectional data flow using separate control inputs: CEAB/LEAB/OEAB govern A-to-B operation, while CEBA/LEBA/OEBA manage B-to-A flow. This architecture allows simultaneous latching on one path while outputting from the other, eliminating bus contention and enabling pipelined data transfer in systems like memory-mapped peripherals.

What package type and dimensions does SN74F543DWE4 use?

SN74F543DWE4 uses a 24-pin SOIC (DW) package per JEDEC MS-013, with body dimensions of 15.4 mm × 7.5 mm and 1.27 mm lead pitch. It is RoHS-compliant, MSL Level-1 rated for 260°C reflow, and marked "F543" on the top surface. This footprint matches legacy 74F/74LS SOIC-24 devices for drop-in replacement in existing layouts.

Can SN74F543DWE4 operate reliably at 4.5 V supply voltage?

Yes, SN74F543DWE4 is fully specified to operate at V_CC = 4.5 V minimum, with guaranteed performance across all recommended parameters including output drive (I_OL = 64 mA on B-side), propagation delay (t_PLH/t_PHL ≤ 12.5 ns), and input thresholds (V_IH ≥ 2.0 V). This makes it suitable for systems with nominal 5 V rails that may dip during transient load conditions.

How does the latch-enable logic work for A-to-B data flow in SN74F543DWE4?

In SN74F543DWE4, A-to-B data flow requires CEAB low to activate the path. With CEAB low and LEAB low, the A-to-B latches are transparent - A inputs appear immediately at the B outputs. A low-to-high transition on LEAB captures and stores the A data; subsequent changes to A inputs no longer affect the B outputs until LEAB is pulsed again. This enables precise, clock-edge-aligned data capture synchronized to system control signals.