onsemi 74LCXH2245SJX

Overview

74LCXH2245SJX 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 direction control via T/R, delivers ≤7.0 ns propagation delay at 3.3 V, supports ±12 mA B-port drive, and eliminates external pull-ups on floating inputs.

For engineers reviewing the 74LCXH2245SJX datasheet, pinout, applications, or equivalent options, key selection criteria include bidirectional voltage-level translation capability, bushold-enabled input stability without external biasing, B-port EMI-reducing series termination, and compatibility with 2.5 V/3.3 V system buses requiring low-skew, high-drive transceivers.

Technical Context

The 74LCXH2245SJX implements a non-inverting bidirectional buffer architecture with independent 3-STATE control (OE) and data flow direction control (T/R), enabling dynamic bus arbitration in shared-memory or peripheral interface applications. Its bushold circuitry actively maintains valid logic states on A0–A7 and B0–B7 inputs when un-driven, eliminating reliance on PCB-level pull resistors.

B-port outputs integrate patented 26 Ω series resistors to suppress overshoot/undershoot during fast switching, while A-port outputs provide higher drive strength (±24 mA at 3.0 V). The device operates across 2.3–3.6 V V_CC, tolerates 5 V on control inputs (OE, T/R), and meets JEDEC J-STD-020B Pb-free requirements in its SOP package.

Key Specifications

Pinout & Package

Pb-Free 20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3 mm wide - RoHS-compliant surface-mount package with standard 0.65 mm lead pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LCXH2245SJX, the 74LVC245APW offers symmetric high-drive but adds BOM complexity, while the SN74AVC245DGVR extends voltage range downward at the cost of EMI mitigation and floating-input resilience - making 74LCXH2245SJX optimal for stable, noise-sensitive 2.5 V/3.3 V bus bridging.

Availability

74LCXH2245SJX is available at Aetrix Electronics and suitable for PCI bus interfacing, memory expansion modules, industrial I/O expansion, and legacy system upgrades requiring stable component supply and long-term obsolescence management.

Supply support for 74LCXH2245SJX 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 of high-performance analog and mixed-signal ICs, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and communications infrastructure.

The 74LCXH2245SJX belongs to the LCXH family of low-voltage CMOS transceivers engineered specifically for robust, low-noise bidirectional bus interfacing in mixed-voltage embedded systems - emphasizing bushold stability, EMI reduction, and 5 V-tolerant control.

FAQ

What is the function of the bushold circuitry in the 74LCXH2245SJX?

The bushold circuitry in the 74LCXH2245SJX actively maintains valid logic states on all 16 I/O pins (A0–A7 and B0–B7) when inputs are floating or un-driven, eliminating the need for external pull-up or pull-down resistors. This reduces BOM cost and PCB space while preventing undefined logic states that could cause system instability. The 74LCXH2245SJX specifies minimum bushold drive current of 45 µA at VIN = 0.7 V, ensuring reliable hold behavior across its 2.3–3.6 V operating range.

Does the 74LCXH2245SJX support true bidirectional data flow without external direction logic?

Yes, the 74LCXH2245SJX supports true bidirectional data flow using its dedicated T/R (Transmit/Receive) input pin: when T/R is LOW, data flows from B-side to A-side; when HIGH, data flows from A-side to B-side. This internal direction control eliminates the need for external multiplexers or discrete logic to manage bus arbitration. The 74LCXH2245SJX integrates this functionality within a single 20-pin SOP package, enabling compact, low-latency bidirectional interfacing.

What is the purpose of the 26 Ω series resistors on the B outputs of the 74LCXH2245SJX?

The 26 Ω series resistors integrated into all B-port outputs of the 74LCXH2245SJX suppress output overshoot and undershoot during fast switching transitions, thereby reducing EMI emissions and improving signal integrity on high-speed traces. These resistors are factory-trimmed and do not require external components. Unlike A-port outputs, which prioritize maximum drive strength (±24 mA), the B-port's 26 Ω termination makes the 74LCXH2245SJX especially suitable for driving longer or more capacitive bus segments where ringing is a concern.

Can the 74LCXH2245SJX be used with a 5 V microcontroller for control signaling?

Yes, the 74LCXH2245SJX accepts 5 V logic levels on its OE and T/R control inputs while operating from a 2.3–3.6 V V_CC supply - a feature explicitly specified in its DC Electrical Characteristics table. This 5 V tolerance allows direct connection to legacy 5 V microcontrollers or FPGAs without level-shifting circuitry. However, the 74LCXH2245SJX's I/O ports (A0–A7, B0–B7) are not 5 V tolerant and must interface only with 2.5 V or 3.3 V logic domains.

What package type does the 74LCXH2245SJX use, and is it RoHS-compliant?

The 74LCXH2245SJX uses a Pb-Free 20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3 mm wide (Package Number M20D), and complies with JEDEC J-STD-020B for lead-free manufacturing. Its gull-wing lead configuration supports standard reflow soldering processes. This package is distinct from the SOIC (M20B), SSOP (MSA20), and TSSOP (MTC20) variants - the "SJ" suffix in 74LCXH2245SJX explicitly denotes the SOP variant, and the "X" indicates tape-and-reel packaging.