STMicroelectronics 74LCX245MTR

Overview

74LCX245MTR from STMicroelectronics is a low-voltage CMOS octal bus transceiver (3-state) with 5V-tolerant inputs and outputs, operating from 2.0V to 3.6V. It supports bidirectional asynchronous data transfer between buses, features DIR-controlled direction and G-enabled 3-state isolation, delivers 7.0 ns max propagation delay at 3V, ±24 mA output drive, and meets PCI bus levels at 24 mA.

For engineers reviewing the 74LCX245MTR datasheet, 74LCX245MTR pinout, 74LCX245MTR application, or 74LCX245MTR equivalent, key selection criteria include 5V-tolerant I/O compatibility with 3.3V core logic, symmetrical 24 mA drive strength, latch-up immunity >500 mA, ESD robustness (HBM >2 kV), and SO-20 package footprint for legacy 74-series board upgrades.

Technical Context

The device implements dual-bus bidirectional communication via a single DIR input that selects data flow direction (A→B or B→A), while the active-low G input enables or disables all outputs into high-impedance state. Its C2MOS process ensures rail-to-rail 5V-tolerant I/O operation even when VCC = 3.3V, eliminating level-shifter requirements in mixed-voltage systems.

Propagation delays are balanced (tPLH ≅ tPHL), skew is limited to 1.0 ns across outputs, and power-down protection prevents current backflow during VCC = 0V conditions. Input leakage remains ≤±5 µA over full voltage range, and output impedance is symmetrical (|IOH| = IOL ≥24 mA at VCC = 3.0–3.6V).

Key Specifications

Pinout & Package

74LCX245MTR is housed in a 20-pin SOIC (SO-20) package per JEDEC MS-013, with 0.300" body width and 1.27 mm pitch. Pin 1 is marked by a beveled corner or dot; pin 10 is GND, pin 20 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LVC245APW and SN74ALVC245PWR, the 74LCX245MTR uniquely combines guaranteed 5V I/O tolerance, JESD17 latch-up immunity, and PCI-compliant drive at 3.3V-making it the only choice for industrial backplane and hot-swap applications requiring both robustness and interoperability.

Availability

74LCX245MTR is available at Aetrix Electronics and suitable for PCI add-in card design, 3.3V/5V bus bridging, and hot-swappable module backplane applications requiring stable component supply and long-term lifecycle support.

Supply support for 74LCX245MTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering silicon solutions for automotive, industrial, and consumer markets since 1987.

The 74LCX series was engineered specifically for low-voltage, high-speed interoperability between 3.3V logic and legacy 5V systems-targeting PCI, ISA, and mixed-supply embedded interfaces where reliability and pin compatibility are critical.

FAQ

Can 74LCX245MTR operate with VCC = 1.8V?

No. The recommended operating VCC range is 2.0V to 3.6V per datasheet Section 4. While data retention is specified down to 1.5V, functional operation-including guaranteed propagation delay, drive strength, and logic thresholds-is not supported below 2.0V. Operating at 1.8V may result in undefined outputs or timing violations.

Is the 74LCX245MTR pin-compatible with standard 74HC245?

Yes-pinout and function are identical to 74 series 245 devices including 74HC245 and 74LS245. All 20 pins match in position and role (DIR, G, A1–A8, B1–B8, GND, VCC). However, VCC must be 2.0–3.6V, and inputs tolerate up to 5.5V-enabling drop-in replacement in existing layouts with appropriate supply adjustment.

What happens if DIR and G are both left floating?

Both DIR and G have internal pull-downs (per datasheet truth table and input leakage specs), so floating inputs default to LOW. This causes continuous A→B data flow with outputs enabled-potentially causing bus contention if A and B buses drive conflicting values. Always tie unused control inputs to defined logic levels via external resistors or firmware initialization.

Does 74LCX245MTR support hot-plug operation with VCC = 0V applied?

Yes-power-down protection ensures no current flows into VCC when unpowered. Inputs and outputs remain high-impedance and immune to damage from 5V signals applied during insertion. However, G must be held HIGH (via external pull-up) to maintain high-Z state until VCC stabilizes; otherwise, transient enable may occur during power ramp.