NXP Semiconductors 74HC243DB,118

Overview

74HC243DB,118 from NXP Semiconductors (formerly Philips) is a quad non-inverting 3-state bus transceiver for asynchronous bidirectional data transfer between two 4-bit buses. It features dual independent output-enable inputs (OEA and OEB), operates from 2.0 V to 6.0 V, delivers 6 ns typical propagation delay at 5 V/15 pF, and supports −40 °C to +125 °C ambient operation in SSOP14 packaging. It enables isolated bus communication in industrial control backplanes.

For engineers reviewing the 74HC243DB,118 datasheet, 74HC243DB,118 pinout, 74HC243DB,118 application, or 74HC243DB,118 equivalent, key selection considerations include its true (non-inverting) output logic, 3-state bus isolation capability, JEDEC 7A compliance, and SSOP14 thermal/power performance versus DIP/SO alternatives.

Technical Context

The 74HC243DB,118 implements four independent bidirectional data paths with separate active-low enable controls per direction (OEA for A→B, OEB for B→A). Each path passes signals without inversion and enters high-impedance state when its respective enable is deasserted.

Its CMOS silicon-gate architecture ensures LSTTL pin compatibility while delivering low static current (≤160 µA at 6 V/125 °C) and dynamic power dissipation governed by CPD = 26 pF. The device meets HBM ESD >2000 V and MM ESD >200 V per JESD22 standards.

Key Specifications

Pinout & Package

74HC243DB,118 is housed in a plastic shrink small outline package (SSOP14) with 14 leads, 5.3 mm body width, and 0.65 mm lead pitch per SOT337-1 standard. This compact surface-mount package supports high-density PCB layouts and offers improved thermal resistance over SO14.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC243DB,118, the 74HC242DB,118 requires system-level polarity correction, while SN74HC243PWR offers identical functionality with alternate branding and sourcing-making it suitable for second-source assurance without layout or firmware changes.

Availability

74HC243DB,118 is available at Aetrix Electronics and suitable for industrial backplane interfaces, automotive sensor hubs, legacy bus extensions, and ATE signal routing requiring stable component supply across extended temperature ranges.

Supply support for 74HC243DB,118 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

NXP Semiconductors, formerly Philips Semiconductors, is a global leader in high-performance mixed-signal ICs for automotive, industrial, and IoT applications.

The 74HC243DB,118 belongs to NXP's 74HC logic family, designed specifically for robust, low-power, pin-compatible replacements of legacy TTL bus interface components in harsh-environment systems.

FAQ

What is the maximum clock frequency supported by the 74HC243DB,118 in a bidirectional data path?

The 74HC243DB,118 does not operate on a clock signal-it is an asynchronous transceiver. Its usable data rate depends on propagation delay and load conditions. With 6 ns typical t_PHL/t_PLH at 5 V/15 pF and 13 ns max output transition time, it supports reliable point-to-point data transfer up to approximately 83 MHz in well-terminated, low-capacitance configurations. System-level timing must account for board trace delays and setup/hold margins for connected devices.

Can the 74HC243DB,118 be used with a 3.3 V supply voltage?

Yes, the 74HC243DB,118 is fully specified for operation from 2.0 V to 6.0 V, including 3.3 V nominal supplies. At V_CC = 3.3 V, VIH is guaranteed ≥2.1 V and VIL ≤1.35 V, ensuring compatibility with standard 3.3 V CMOS logic families. Output drive strength remains sufficient for typical 3.3 V bus loads, with VOH ≥3.1 V and VOL ≤0.33 V at 6 mA sink/source.

How does the 74HC243DB,118 differ from the 74HC243D in terms of package and thermal performance?

The 74HC243DB,118 uses SSOP14 (SOT337-1), while 74HC243D uses SO14 (SOT108-1). Both have 14 leads and 0.65 mm pitch, but SSOP14 has a wider 5.3 mm body versus SO14's 3.9 mm-improving heat spreading. Power dissipation is rated at 500 mW for both packages above 70 °C, though SSOP14's larger footprint provides marginally better thermal resistance in high-density layouts.

Is the 74HC243DB,118 pin-compatible with 74LS243 or other TTL transceivers?

Yes-the 74HC243DB,118 is explicitly designed to be pin compatible with low-power Schottky TTL (LSTTL) devices such as 74LS243, per JEDEC Standard No. 7A. Pin functions, numbering, and DC/AC electrical behavior (including input thresholds and output drive) are aligned to enable direct replacement in existing LSTTL-based designs without PCB modification.

What is the purpose of the two no-connect (n.c.) pins on the 74HC243DB,118?

Pins 2 and 12 of the 74HC243DB,118 are designated as no-connect (n.c.) per the official Philips/NXP datasheet. These correspond to internal die pads not bonded to package leads. They must remain unconnected on the PCB-neither tied to GND, V_CC, nor routed-to prevent unintended coupling, noise injection, or mechanical stress on bond wires. Leaving them floating is electrically and mechanically safe.