onsemi 74F543PC

Overview

74F543PC from Fairchild Semiconductor is an octal registered transceiver with dual-directional 8-bit data flow control, featuring separate A-to-B and B-to-A latch enable (LEAB/LEBA) and output enable (OEAB/OEBA) inputs, A outputs rated for 24 mA sink current, B outputs rated for 64 mA sink current, and operation across 0°C to +70°C ambient temperature. It serves in bidirectional bus interfacing between microprocessor data buses and peripheral subsystems.

For engineers reviewing the 74F543PC datasheet, pinout, applications, or equivalent options, key selection criteria include independent latch/output control per direction, asymmetric drive strength (24 mA vs. 64 mA), 3-STATE B-side outputs, propagation delays under 12.5 ns, and PDIP-24 package compatibility with legacy through-hole layouts.

Technical Context

The 74F543PC integrates two independent sets of eight D-type latches-one for A-to-B and one for B-to-A data paths-with dedicated CEAB/CEBA (enable), LEAB/LEBA (latch), and OEAB/OEBA (output enable) control signals. Each register operates in transparent mode when its latch enable is LOW and stores data on the LOW-to-HIGH transition.

Its 3-STATE outputs support bidirectional bus sharing: A0–A7 function as inputs or high-impedance outputs during B-to-A transfer, while B0–B7 serve as inputs or high-impedance outputs during A-to-B transfer. Output drive capability differs-B-side sinks up to 64 mA, A-side up to 24 mA-enabling optimized loading for asymmetrical bus topologies.

Key Specifications

Pinout & Package

74F543PC is housed in a 24-lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-011, 0.600" wide, with through-hole mounting and standard 0.1" pin pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74F543PC, the 74ACT543PC offers superior speed and power efficiency but sacrifices asymmetric drive strength, while the 74F541PC reduces functionality to unidirectional flow-making it a partial substitute only when B-to-A transfer is absent in the target design.

Availability

74F543PC is available at Aetrix Electronics and suitable for microprocessor bus interface, memory expansion subsystem, and industrial I/O module backplane applications requiring stable component supply and long-term obsolescence management.

Supply support for 74F543PC 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in analog and discrete power products, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and legacy systems.

The 74F543PC belongs to the Fast TTL (74F) logic family, designed for high-speed, robust bidirectional data transfer in commercial-grade embedded control and instrumentation systems where timing predictability and through-hole assembly are required.

FAQ

What is the maximum operating frequency supported by the 74F543PC?

The 74F543PC does not specify a clock frequency, as it is an asynchronous registered transceiver. Its usable data rate depends on propagation delay and system timing margins: with max t_PLH/t_PHL = 12.5 ns and t_PZL/t_PLZ = 9.0/8.0 ns, it supports reliable bidirectional bus toggling up to approximately 40 MHz in well-designed layouts. The 74F543PC's performance is governed by setup/hold times (t_S/t_H = 3.5 ns) and latch pulse width (t_W(L) = 9.0 ns), not a clock signal.

Can the 74F543PC be used with a 3.3 V system?

No, the 74F543PC is specified only for 4.5 V to 5.5 V operation and is not 3.3 V tolerant. Its input thresholds (V_IL = 0.8 V, V_IH = 2.0 V) and output drive characteristics assume a 5 V rail; applying 3.3 V to V_CC results in undefined logic behavior and insufficient output voltage swing. For 3.3 V systems, consider logic-level translators or 3.3 V–compatible transceivers-not the 74F543PC.

Does the 74F543PC support hot insertion or live bus swapping?

No, the 74F543PC is not designed for hot insertion. Its absolute maximum ratings do not include powered-insertion stress testing, and its 3-STATE outputs lack bus-fault protection or current-limiting during transitional states. Applying V_CC or signals while other devices on the bus are active may cause latch-up or excessive current flow. System-level hot-swap capability requires external protection circuitry-not inherent to the 74F543PC.

What is the purpose of the CEAB and CEBA pins on the 74F543PC?

The CEAB (A-to-B Enable) and CEBA (B-to-A Enable) pins on the 74F543PC are active-LOW inputs that gate access to their respective latch registers. When CEAB is LOW, the A-to-B latches accept data from A0–A7 or allow LEAB to control latching; when HIGH, the A latches are isolated from A inputs. Similarly, CEBA controls access to the B-to-A latches. These enables provide architectural isolation-preventing unintended data capture during bus arbitration-and are distinct from OEAB/OEBA, which control only output driver activation. This separation is fundamental to the 74F543PC's dual-control architecture.

Is the 74F543PC pin-compatible with the 74LS543?

Yes, the 74F543PC is pin-compatible with the 74LS543 in the PDIP-24 package (N24A), sharing identical pin assignments for all signals (OEAB, A0–A7, GND, CEAB, LEAB, V_CC, B0–B7, LEBA, CEBA, OEBA). However, the 74F543PC delivers faster propagation (≤12.5 ns vs. ≤25 ns for LS), higher output drive (64 mA vs. 24 mA on B-side), and greater power supply current (ICCL up to 125 mA vs. ~60 mA for LS). System designers may directly replace 74LS543 with 74F543PC where timing and drive upgrades are beneficial-but must verify power delivery and thermal margins due to higher ICC.