onsemi 74LCXR2245MSA

Overview

74LCXR2245MSA from Fairchild Semiconductor is a low-voltage bidirectional transceiver with 5V-tolerant I/O, 26Ω integrated series resistors on all A/B ports, 8.0ns max propagation delay at 3.3V, ±12mA drive strength at 3.0V, and 3-STATE control via OE/T/R inputs-designed for voltage-level translation between 2.3–3.6V buses and legacy 5V systems in embedded interface applications.

For engineers reviewing the 74LCXR2245MSA datasheet, pinout, applications, or equivalent options, key selection criteria include 5V tolerance without external clamping, built-in 26Ω termination to suppress overshoot/undershoot, live-insertion support, power-down high-impedance behavior, and SSOP-20 packaging for space-constrained board layouts.

Technical Context

The 74LCXR2245MSA implements eight non-inverting bidirectional buffers with independent direction control (T/R) and global 3-STATE enable (OE), enabling dynamic bus arbitration in mixed-voltage systems. Its advanced CMOS process delivers high-speed operation while maintaining sub-10µA quiescent current.

All I/O pins tolerate 0–5.5V input voltage regardless of VCC (2.3–3.6V), and internal 26Ω series resistors are present on both A0–A7 and B0–B7 terminals-reducing EMI and signal integrity issues without requiring external termination components.

Key Specifications

Pinout & Package

74LCXR2245MSA is housed in a 20-lead Shrink Small Outline Package (SSOP), JEDEC MO-150 compliant, 5.3mm body width, 0.65mm lead pitch, with exposed pad not present. Pin 1 marked by notch or dot; pin numbering follows standard counter-clockwise convention from top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC2245APW and 74AVC2245PW, the 74LCXR2245MSA uniquely combines 5V tolerance, integrated 26Ω termination, and industrial temperature support - making it the only option that eliminates both external level-shifting and series-resistor components in mixed-voltage bus designs.

Availability

74LCXR2245MSA is available at Aetrix Electronics and suitable for industrial PLC backplanes, embedded microcontroller expansion buses, automotive body control modules, and test equipment digital I/O cards requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74LCXR2245MSA 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, analog, and interface ICs before its acquisition by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and automotive systems.

The 74LCXR2245MSA belongs to the LCXR family of low-voltage, 5V-tolerant transceivers designed specifically for seamless integration between next-generation low-power logic and legacy 5V infrastructure - emphasizing robustness, signal integrity, and design simplicity.

FAQ

What is the maximum data rate supported by the 74LCXR2245MSA?

The 74LCXR2245MSA supports reliable operation up to approximately 125MHz under typical conditions (VCC = 3.3V, CL = 50pF), derived from its 8.0ns maximum propagation delay and matched rise/fall times. Actual achievable data rate depends on bus loading, trace length, and noise margin; for sustained 100MHz operation, the integrated 26Ω series resistors help maintain clean edges without external damping.

Does the 74LCXR2245MSA require external pull-up resistors on OE or T/R inputs?

Yes - the OE input must be tied to VCC through a pull-up resistor during power-up/down to guarantee high-impedance state; Fairchild specifies minimum resistor value based on driver sourcing capability. The T/R input does not require a pull-up but must be actively driven to avoid undefined direction; floating T/R may cause bus contention or metastability.

Can the 74LCXR2245MSA operate with a 2.5V supply while interfacing to 5V signals?

Yes - the 74LCXR2245MSA is fully specified for VCC = 2.3–3.6V and maintains 0–5.5V input/output voltage tolerance across that entire range. At 2.5V supply, it delivers ±4mA output drive and retains full 5V tolerance, enabling safe, robust interfacing between 2.5V SoCs and 5V peripherals without level-shifting circuitry.

How does the 26Ω series resistor affect signal integrity in the 74LCXR2245MSA?

The 26Ω series resistor on each A/B port output damps high-frequency ringing caused by transmission-line effects, reducing overshoot and undershoot by limiting slew rate and matching typical PCB trace impedance. This improves eye diagram margin in point-to-point or short-bus configurations up to ~15cm, eliminating need for discrete 27Ω resistors and associated layout complexity.

Is the 74LCXR2245MSA pin-compatible with other 20-pin SSOP transceivers like the 74LVC2245?

No - although both use 20-pin SSOP packages, the 74LCXR2245MSA has distinct pin assignments: OE is on pin 1 (active-low), T/R on pin 2, A0–A7 on pins 3–10, GND on pin 11, B0–B7 on pins 12–19, and VCC on pin 20. The 74LVC2245 uses different pinout ordering and lacks integrated series resistors, so PCB layout and firmware initialization differ significantly.