NXP Semiconductors N74F243D,623

Overview

N74F243D,623 from Philips Semiconductors is a quad non-inverting 3-state transceiver IC used for bidirectional data bus interfacing in TTL-compatible systems. It features 4-bit bidirectional data paths, dual active-low output enables (OEA, OEB), propagation delay of 4.0 ns (typ), supply current of 66 mA (typ), and operates at VCC = 5.0 V ±10% over 0°C to +70°C.

For engineers reviewing the N74F243D,623 datasheet, N74F243D,623 pinout, N74F243D,623 application, or N74F243D,623 equivalent, key selection criteria include 3-state bus driving capability, non-inverting logic direction, dual enable control timing, and SO14 package compatibility with legacy 74F logic designs.

Technical Context

The N74F243D,623 implements two independent 4-bit bidirectional data channels with separate active-low output enables (OEA for A→B path, OEB for B→A path). Its non-inverting architecture ensures signal polarity preservation across both directions, distinguishing it from the inverting 74F242 variant.

It supports TTL-level input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), delivers ±15 mA high-level and 64 mA low-level output drive, and meets AC timing specs including tPLH/tPHL ≤ 6.5 ns (max), tPZH/tPZL ≤ 8.5 ns (max), and tPHZ/tPLZ ≤ 7.0 ns (max) under CL = 50 pF, RL = 500 Ω conditions.

Key Specifications

Pinout & Package

Package: Plastic small outline (SO14), 14-lead, 3.9 mm body width (SOT108-1), RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F243N and 74ACT243SCX, the N74F243D,623 provides optimal drop-in compatibility with existing 74F-based designs in SO14 footprint, balancing speed, drive strength, and legacy interface fidelity without requiring layout or logic-level changes.

Availability

N74F243D,623 is available at Aetrix Electronics and suitable for microprocessor bus interface, memory expansion module, and industrial PLC backplane applications requiring stable component supply and long-term obsolescence management.

Supply support for N74F243D,623 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

Philips Semiconductors (now NXP Semiconductors) is a global semiconductor innovator founded in the Netherlands, known for pioneering TTL, CMOS, and mixed-signal ICs across computing, industrial, and consumer markets.

The 74F logic family - including N74F243D,623 - was engineered for high-speed, low-power bipolar TTL performance in mid-1980s to early-1990s computing and instrumentation systems, targeting board-level bus interfacing with robust noise immunity and predictable timing.

FAQ

What is the function of OEA and OEB on the N74F243D,623?

OEA (pin 2) and OEB (pin 12) are active-low output enable inputs controlling direction and 3-state behavior. When OEA is low and OEB is high, data flows from A0–A3 to B0–B3; when OEB is low and OEA is high, data flows from B0–B3 to A0–A3. Both high places all outputs in high-impedance state. This dual-enable architecture is intrinsic to the N74F243D,623 design and enables flexible bus arbitration.

Is the N74F243D,623 pin-compatible with the 74F242?

Yes, the N74F243D,623 shares identical pinout and package with the 74F242, including all 14 pins (A0–A3, B0–B3, OEA, OEB, VCC, GND). However, the N74F243D,623 implements non-inverting logic, whereas the 74F242 is inverting - this functional difference must be accounted for in circuit design and cannot be treated as a blind replacement.

What is the maximum capacitive load the N74F243D,623 can drive reliably?

The N74F243D,623 is characterized for CL = 50 pF in AC specifications, with propagation delays and enable/disable times guaranteed under that condition. While it can drive higher capacitance, timing margins degrade beyond 50 pF; for loads >75 pF, series termination or buffer staging is recommended. This 50 pF limit is explicitly defined in the N74F243D,623 datasheet AC test conditions.

Does the N74F243D,623 support mixed-voltage operation (e.g., 3.3 V inputs)?

No - the N74F243D,623 is specified only for VCC = 4.5 V to 5.5 V and TTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V). It does not tolerate 3.3 V logic levels on inputs without external level translation, as its input structure is optimized for 5 V bipolar operation and lacks 5 V-tolerant CMOS input circuitry.

What is the short-circuit current rating for the N74F243D,623 outputs?

The N74F243D,623 has a short-circuit output current (IOS) rating of –100 mA to –225 mA (min to max) under VCC = MAX, with the datasheet specifying that no more than one output should be shorted at a time. This rating is measured per-output and reflects the bipolar output stage's inherent current-limiting behavior - a key reliability parameter documented for the N74F243D,623 in its Absolute Maximum Ratings table.