onsemi 74LCXH2245WMX

Overview

74LCXH2245WMX from Fairchild Semiconductor is a low-voltage bidirectional transceiver with bushold inputs and integrated 26 Ω series resistors on B-port outputs, designed for 2.3–3.6 V bus interfacing. It features 8-bit non-inverting data flow control via T/R input, 3-STATE outputs enabled/disabled by OE, and supports A↔B bidirectional data transfer in systems requiring voltage-level translation between 2.5 V/3.3 V domains.

For engineers reviewing the 74LCXH2245WMX datasheet, pinout, applications, or equivalent options, key selection criteria include bushold-enabled floating-input immunity, B-port output overshoot suppression, 7.0 ns max propagation delay at 3.3 V, ±12 mA B-port drive capability, and 5 V-tolerant control inputs (OE, T/R) for mixed-voltage system integration.

Technical Context

The 74LCXH2245WMX implements a dual-bus bidirectional interface where direction is controlled by the T/R signal and output enable/disable is managed by OE - both inputs are 5 V tolerant and feature bushold circuitry to maintain valid logic states without external pull resistors. Its A and B ports each support 8 I/Os with independent 3-STATE control, and all inputs include active bushold with minimum hold current of 45 µA at 2.3 V.

B-port outputs integrate patented 26 Ω series resistors to reduce EMI and suppress overshoot/undershoot during switching, while A-port outputs provide higher drive strength (±24 mA at 3.0 V). The device operates across –40°C to +85°C with quiescent ICC ≤ 10 µA and latch-up immunity exceeding 500 mA per JEDEC JESD78.

Key Specifications

Pinout & Package

74LCXH2245WMX is packaged in a 20-lead SOIC (JEDEC MS-013, 0.300" wide), package number M20B, with standard pin spacing and thermal profile suitable for reflow soldering and industrial PCB assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LCXH2245WMX, the Nexperia part reduces component count only if external pull resistors are already present, while the TI part eliminates direction-control logic overhead but forfeits the targeted B-port EMI mitigation that defines the Fairchild device's value in noise-sensitive routing.

Availability

74LCXH2245WMX is available at Aetrix Electronics and suitable for industrial backplane interfaces, low-power microcontroller bus extensions, hot-pluggable module communication, and EMI-sensitive medical data acquisition requiring stable component supply and long-term lifecycle support.

Supply support for 74LCXH2245WMX 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 power management, signal conditioning, and logic ICs before its acquisition by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and communications infrastructure.

The 74LCXH2245WMX belongs to the LCXH family of low-voltage, high-speed CMOS transceivers engineered specifically for robust bidirectional bus interfacing in mixed-voltage systems with stringent EMI and floating-input constraints.

FAQ

What is the function of the bushold circuitry in the 74LCXH2245WMX?

The bushold circuitry in the 74LCXH2245WMX actively maintains valid logic states (HIGH or LOW) on all A0–A7 and B0–B7 inputs when they are left unconnected or floating, eliminating the need for external pull-up or pull-down resistors. This feature ensures reliable operation during hot-swap events, power sequencing, or partial system initialization - a key advantage in modular and field-upgradeable equipment where I/Os may be temporarily disconnected. The 74LCXH2245WMX specifies minimum bushold current of 45 µA at 2.3 V VCC.

Does the 74LCXH2245WMX support true 5 V operation on its power supply pin?

No, the 74LCXH2245WMX does not operate from a 5 V VCC supply - its absolute maximum VCC rating is 7.0 V, but its recommended operating range is strictly 2.3 V to 3.6 V. However, its OE and T/R control inputs are 5 V tolerant, meaning they safely accept 0–5.5 V logic signals even when VCC is 2.5 V or 3.3 V. This allows the 74LCXH2245WMX to interface directly with legacy 5 V controllers without level-shifting circuitry, while maintaining low-voltage core operation for power efficiency and compatibility with modern logic families.

How does the 26 Ω series resistor on the B outputs of the 74LCXH2245WMX improve signal integrity?

The integrated 26 Ω series resistor on each B-port output (B0–B7) of the 74LCXH2245WMX acts as a source termination to dampen signal reflections caused by impedance mismatches on PCB traces, thereby reducing overshoot and undershoot. Measured dynamic performance shows quiet-output peak VOL ≤ 0.8 V under 50 pF load at 3.3 V, confirming effective suppression. This built-in termination eliminates the need for 8 discrete resistors, saves board space, and ensures consistent damping across all B-side signals - particularly valuable in compact layouts or when routing to multiple peripherals with varying trace lengths. The 74LCXH2245WMX achieves this without compromising propagation delay (7.0 ns max).

Can the 74LCXH2245WMX be used for unidirectional data transfer?

Yes, the 74LCXH2245WMX can be configured for unidirectional operation by holding the T/R input at a fixed logic level (HIGH for A→B, LOW for B→A) while using OE to enable/disable the entire transceiver. In this mode, it functions as an octal non-inverting buffer with 3-STATE capability - for example, driving a 3.3 V data bus from a 2.5 V source (A→B) or vice versa (B→A). The 74LCXH2245WMX retains all its key features in unidirectional use, including bushold on all I/Os, 5 V-tolerant controls, and B-port damping, making it suitable for fixed-path interconnects where bidirectional flexibility is not required.

What is the thermal and reliability qualification of the 74LCXH2245WMX package?

The 74LCXH2245WMX in SOIC package (M20B) is qualified per JEDEC standards for industrial temperature operation (–40°C to +85°C), with latch-up immunity exceeding 500 mA per JESD78 Class II. Its SOIC construction uses Pb-free terminations compliant with JEDEC J-STD-020B, supporting standard reflow profiles. Thermal resistance (θJA) is typical for 20-lead SOIC (~120°C/W), and the device exhibits ≤10 µA quiescent ICC, minimizing self-heating. The 74LCXH2245WMX has demonstrated field reliability in telecom backplanes and industrial controllers for over two decades, with no known early-life failure modes reported in Aetrix's supply chain history.