onsemi 74LCXH2245WM

Overview

74LCXH2245WM from Fairchild Semiconductor is a low-voltage, 8-bit bidirectional transceiver with bushold inputs and integrated 26 Ω series resistors on B-side outputs, designed for 2.3–3.6 V bus interfacing between mixed-voltage domains. It features 3-STATE control via OE and directional control via T/R, delivers ≤7.0 ns propagation delay at 3.3 V, and supports ±12 mA B-port drive at 3.0 V.

For engineers reviewing the 74LCXH2245WM datasheet, pinout, applications, or equivalent options, key selection criteria include bushold-enabled floating-input robustness, B-port EMI-reducing series termination, 5 V-tolerant control pins, and SOIC-20 packaging for legacy board compatibility.

Technical Context

The 74LCXH2245WM implements non-inverting bidirectional data flow controlled by a single T/R signal and disabled globally via OE, placing both A and B ports in high-impedance state. Its bushold circuitry actively holds unused inputs at valid logic levels without external resistors, reducing BOM count and layout complexity.

Each B-port output includes a built-in 26 Ω series resistor to suppress overshoot/undershoot during fast switching, while A-port outputs provide higher drive (±24 mA at 3.0 V). The device operates across 2.3–3.6 V V_CC, with 5 V-tolerant OE and T/R inputs enabling direct interface to 5 V controllers.

Key Specifications

Pinout & Package

74LCXH2245WM is housed in a 20-lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" wide (Package Number M20B), with standard pin spacing of 0.050" (1.27 mm) and body width of 7.5 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LVC245APW and SN74AVC245DBR, the 74LCXH2245WM uniquely combines bushold input retention, B-port integrated 26 Ω termination, and proven industrial reliability - making it optimal for mixed-voltage bus designs where layout simplicity and noise immunity are prioritized over raw speed or minimum V_CC.

Availability

74LCXH2245WM is available at Aetrix Electronics and suitable for PCI bus interface, memory expansion module, and industrial PLC backplane applications requiring stable component supply, long-term lifecycle support, and SOIC-20 footprint compatibility.

Supply support for 74LCXH2245WM 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 leading designer and manufacturer of high-performance analog and power ICs, acquired by ON Semiconductor in 2016. Its legacy logic portfolio remains widely deployed in industrial and computing infrastructure.

The 74LCXH2245WM belongs to the LCXH family of low-voltage, high-speed transceivers engineered for robust mixed-signal bus interfacing in 2.5 V/3.3 V systems with legacy 5 V control compatibility.

FAQ

What is the function of the bushold feature in the 74LCXH2245WM?

The bushold feature in the 74LCXH2245WM actively holds unused or floating inputs at their last valid logic state using internal feedback circuitry. This eliminates the need for external pull-up or pull-down resistors on any of its 16 I/O pins (A0–A7, B0–B7), reducing BOM count and improving reliability in hot-swap or partial-power-down scenarios. The 74LCXH2245WM specifies bushold input current ≥45 µA at VIN = 0.7 V, ensuring stable retention across its full 2.3–3.6 V operating range.

Does the 74LCXH2245WM support 5 V logic levels on its data lines?

No - the 74LCXH2245WM does not support 5 V on its A or B data I/O lines. Only the OE and T/R control inputs are 5 V tolerant; A and B port pins operate strictly within the V_CC range of 2.3–3.6 V. Applying 5 V to A0–A7 or B0–B7 may damage the 74LCXH2245WM. For true 5 V bidirectional translation, external level-shifting circuitry or a different device family is required.

What is the purpose of the 26 Ω series resistors on the B outputs of the 74LCXH2245WM?

The 26 Ω series resistors integrated into each B-port output (B0–B7) of the 74LCXH2245WM serve to dampen signal edge overshoot and undershoot, reducing EMI and improving signal integrity on PCB traces. These resistors are absent on the A outputs, allowing higher drive strength (±24 mA) there. The 74LCXH2245WM's datasheet explicitly confirms "equivalent 26 Ω series resistor on B Port outputs" as a defining feature for noise-sensitive applications.

Can the 74LCXH2245WM be used in place of the standard 74LCX245?

No - the 74LCXH2245WM is not a drop-in replacement for the 74LCX245. While both are 8-bit bidirectional transceivers, the 74LCXH2245WM adds bushold inputs and integrated 26 Ω resistors on B outputs, altering electrical behavior and timing. Its truth table and pinout match the 74LCX245, but the enhanced features require verification of system-level compatibility - especially regarding B-port termination effects and bushold interaction with existing bus protocols. The 74LCXH2245WM must be validated per application.

What package type is used for the 74LCXH2245WM?

The 74LCXH2245WM uses a 20-lead Small Outline Integrated Circuit (SOIC) package, JEDEC MS-013 compliant, 0.300" wide, with Package Number M20B. It has a standard SOIC footprint (7.5 mm body width, 1.27 mm lead pitch), making it compatible with legacy PCB layouts designed for similar 20-pin SOIC logic devices. This package is distinct from the SSOP, TSSOP, or SOP variants offered for other 74LCXH2245 ordering codes.