Diodes Incorporated PI74FCT543ATQ

Overview

PI74FCT543ATQ from Pericom Semiconductor is an 8-bit non-inverting latched transceiver with dual 8-bit D-type latches, 25Ω series output resistors, TTL-compatible I/O, and industrial temperature range (–40°C to +85°C). It enables bidirectional data flow between two 8-bit buses using separate A-to-B and B-to-A control logic, and is used in backplane interface and bus isolation applications.

For engineers reviewing the PI74FCT543ATQ datasheet, PI74FCT543ATQ pinout, PI74FCT543ATQ application, or PI74FCT543ATQ equivalent, key selection criteria include latch enable timing (tW = 3.0 ns min), output disable time (tPZL = 4.3 ns max), 25Ω integrated termination, low ground bounce, and compatibility with FAST™-series pinouts at higher speed and lower power.

Technical Context

The PI74FCT543ATQ implements two independent 8-bit transparent/latched data paths with separate CE/LE/OE controls per direction. Each path uses edge-triggered latch enable (LEAB/LEBA active-low) to capture data on LOW-to-HIGH transition, while CEAB/CEBA enable input sampling and OEAB/OEBA control 3-state output drivers.

Its 25Ω series output resistors suppress transmission-line reflections without external termination, and hysteresis on all inputs (200 mV) improves noise immunity. The device operates at 5.0 V ±5% and draws ≤7.3 mA total supply current under full 8-bit toggle at 2.5 MHz.

Key Specifications

Pinout & Package

PI74FCT543ATQ is housed in a 24-pin plastic TQSOP (Thin Quad Small Outline Package) with 0.65 mm pitch and 3.9 mm body width, optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74F543PC and SN74F543N, the PI74FCT543ATQ delivers 3× lower static power, eliminates external termination, and supports surface-mount manufacturing - making it optimal for new industrial designs prioritizing density, noise control, and efficiency.

Availability

PI74FCT543ATQ is available at Aetrix Electronics and suitable for industrial bus interface, backplane isolation, and legacy system upgrade applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for PI74FCT543ATQ 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

Pericom Semiconductor was a fabless provider of high-speed interface and timing solutions, acquired by Diodes Incorporated in 2016; its logic portfolio remains widely deployed in industrial and communications infrastructure.

The PI74FCT series targets 5V logic upgrades, delivering FAST™-compatible pinouts with CMOS efficiency, integrated termination, and robust noise immunity for backplane, bus, and control-plane applications.

FAQ

What is the function of the LEAB and LEBA pins?

LEAB and LEBA are active-low latch enable inputs that control data capture timing. When pulled LOW, they allow transparent data flow from A0–A7 or B0–B7 into their respective latches; a LOW-to-HIGH transition stores the current input state. This edge-triggered behavior ensures synchronous data registration independent of CEAB/CEBA status.

Does PI74FCT543ATQ require external pull-up or pull-down resistors on control inputs?

No external biasing is required. All control inputs (CEAB, CEBA, LEAB, LEBA, OEAB, OEBA) have TTL-compatible thresholds and exhibit hysteresis (200 mV), enabling direct connection to microcontroller GPIOs or other logic outputs without pull resistors - provided driving sources meet VIH ≥ 2.0 V and VIL ≤ 0.8 V.

Can PI74FCT543ATQ operate at 3.3V supply voltage?

No. The device is specified only for 5.0 V ±5% operation. Its input thresholds, output drive strength, and internal 25Ω resistors are calibrated for 5V logic levels. Operating at 3.3V violates absolute maximum ratings and will result in undefined logic states, excessive VOL, and potential damage due to insufficient VCC margin for internal circuitry.

How does the 25Ω series output resistor affect signal integrity?

The integrated 25Ω resistor matches typical PCB trace impedance (50Ω single-ended), reducing reflections at the driver end. This minimizes overshoot, undershoot, and ringing on traces up to ~10 cm, improving eye diagram margins and eliminating the need for 24 discrete SMT resistors - directly lowering BOM cost and layout complexity.