Texas Instruments SN74F543DW

Overview

SN74F543DW from Texas Instruments is an octal registered transceiver with 3-state outputs, implementing dual-directional data flow via back-to-back D-type latches and independent A-to-B/B-to-A control logic. It operates at 5 V (4.5–5.5 V), supports 0°C to 70°C ambient, sinks up to 24 mA on A-side and 64 mA on B-side outputs, and is packaged in a 24-pin SOIC (DW) for bus isolation in legacy TTL systems.

For engineers reviewing the SN74F543DW datasheet, SN74F543DW pinout, SN74F543DW application, or SN74F543DW equivalent, key selection considerations include its dual-latch architecture, asymmetric output drive capability (A: 24 mA / B: 64 mA), 3-state enable timing (tPZH ≤ 10 ns), and compatibility with 5-V TTL logic families in industrial control and instrumentation bus interfaces.

Technical Context

The SN74F543DW implements two independent 8-bit latch paths - A-to-B and B-to-A - each controlled by dedicated CE, LE, and OE inputs. Its dual-register structure enables simultaneous bidirectional data staging without contention, with latch transparency and storage modes triggered by LEAB/LEBA transitions.

Output drivers are asymmetrical: A-side outputs are rated for 24 mA sink current and 3 mA source current; B-side outputs support 64 mA sink and 15 mA source. All outputs enter high-impedance state when respective OE signals are high, enabling shared-bus operation under precise timing control (tPLH/tPHL ≤ 8.5 ns).

Key Specifications

Pinout & Package

SN74F543DW is housed in a 24-pin plastic small-outline integrated circuit (SOIC) package (DW), 7.5 mm wide, with 1.27 mm pitch and gull-wing leads. The package complies with JEDEC MS-012 and is RoHS-compliant with NiPdAu lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F543DW, SN74F541DW omits bidirectional functionality entirely, while SN74F245N consolidates control logic at the expense of independent latch timing and reduced B-side output strength - making SN74F543DW uniquely suited for applications demanding true dual-path staging and asymmetric bus loading.

Availability

SN74F543DW is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy test equipment data buses, embedded instrumentation control panels, and automated calibration system buses requiring stable component supply and long-term obsolescence management.

Supply support for SN74F543DW 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 company founded in 1930, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.

The SN74F543DW belongs to TI's 74F Fast TTL logic family, designed specifically for high-speed, low-latency data routing in commercial-grade control and instrumentation systems operating at 5 V.

FAQ

What is the maximum sink current supported by the B-side outputs of the SN74F543DW?

The B-side outputs (B1–B8) of the SN74F543DW are characterized to sink up to 64 mA per pin under recommended operating conditions (VCC = 4.5 V, TA = 0°C to 70°C). This rating enables direct driving of multiple TTL loads or terminated bus lines without external buffers. Exceeding this current risks parametric shift or reliability degradation. The SN74F543DW datasheet specifies this value in the "recommended operating conditions" table under IOL for B1–B8.

Does the SN74F543DW support operation at 3.3 V?

No, the SN74F543DW is not specified for 3.3 V operation. Its recommended supply range is strictly 4.5 V to 5.5 V, and input thresholds (VIH = 2.0 V, VIL = 0.8 V) are optimized for 5-V TTL compatibility. Applying 3.3 V may result in marginal noise margins, undefined logic states, or failure to meet timing specifications. For 3.3-V systems, consider modern alternatives like the SN74LVC245A, not the SN74F543DW.

How does the latch-enable behavior differ between the A-to-B and B-to-A paths in the SN74F543DW?

In the SN74F543DW, LEAB controls the A-to-B latch: when LEAB is low, A inputs pass transparently to the B latches; a low-to-high transition stores the A data. Similarly, LEBA controls the B-to-A path with identical behavior. These latches operate independently - enabling concurrent staging of data in both directions. This dual-latch architecture is explicitly defined in the SN74F543DW function table and logic diagram, distinguishing it from simpler transceivers.

Is the SN74F543DW pin-compatible with the SN74F245N?

No, the SN74F543DW is not pin-compatible with the SN74F245N. The SN74F543DW uses 24 pins with dedicated CEAB, CEBA, LEAB, LEBA, OEAB, and OEBA inputs, while the SN74F245N uses 20 pins with a single DIR pin and OE. Pin assignments, count, and control signal mapping differ fundamentally - PCB layout changes are required for substitution. This incompatibility is confirmed by TI's official package drawings and pinout diagrams for both devices.

What is the purpose of the CEAB and CEBA inputs on the SN74F543DW?

The CEAB (Chip Enable A-to-B) and CEBA (Chip Enable B-to-A) inputs on the SN74F543DW act as master enables for each data path: CEAB must be low to capture data from A inputs or drive B outputs; CEBA must be low for B-to-A operation. They provide hierarchical control - allowing one direction to be fully disabled while the other remains active - which prevents unintended data flow and simplifies system-level bus arbitration. This dual-CE architecture is documented in the SN74F543DW functional description and truth table.