STMicroelectronics M74HC245RM13TR

Overview

M74HC245RM13TR from STMicroelectronics is an octal non-inverting bus transceiver with 3-state outputs, designed for bidirectional asynchronous data bus communication. It operates across 2V–6V supply, delivers 10ns typical propagation delay at 6V, supports ±6mA symmetrical drive strength, and features pin- and function-compatibility with standard 74-series 245 devices in industrial temperature range (−55°C to +125°C).

For engineers reviewing the M74HC245RM13TR datasheet, M74HC245RM13TR pinout, M74HC245RM13TR application, or M74HC245RM13TR equivalent, key selection criteria include directional control (DIR), output enable (G), high-noise immunity (28% VCC), 3-state isolation timing (tPZL/tPLZ ≤23ns at 6V), and TSSOP-20 package compatibility with space-constrained PCB layouts.

Technical Context

The M74HC245RM13TR implements a dual-bus interface with DIR-controlled data flow direction and active-low G-enabled 3-state output control. Its C2MOS silicon gate process ensures low static current (ICC ≤4µA at 25°C) and robust ESD protection on all inputs.

It supports true bidirectional operation: when G = LOW and DIR = LOW, data flows A→B; when G = LOW and DIR = HIGH, data flows B→A. All eight channels operate simultaneously with balanced tPLH ≅ tPHL propagation delays and matched output impedance (|IOH| = |IOL| ≥6mA).

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5mm × 4.4mm body, 0.65mm pitch, 1.05mm max height, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC245PWR and 74VHC245M, the M74HC245RM13TR offers superior extended temperature performance (−55°C to +125°C), lower quiescent current (4µA vs. 8µA), and STMicroelectronics' industrial-grade reliability-making it optimal for harsh-environment embedded control.

Availability

M74HC245RM13TR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, automated test equipment, and medical imaging subsystems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for M74HC245RM13TR 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, specializing in automotive, industrial, and power discrete solutions with vertical manufacturing and broad analog/mixed-signal IP.

The M74HC245RM13TR belongs to ST's high-speed CMOS logic family, engineered for robust bidirectional bus interfacing in mission-critical industrial and transportation systems where reliability, wide voltage tolerance, and extended temperature operation are essential.

FAQ

What is the maximum capacitive load the M74HC245RM13TR can drive while maintaining specified timing?

The device is characterized for CL = 50pF and 150pF loads in AC testing. At 6V supply, it sustains tPLH/tPHL ≤23ns and tPZL/tPLZ ≤38ns into 150pF. Driving >150pF requires verifying setup/hold margins in the target system, as increased load raises transition time and may affect timing closure in high-speed buses.

Can the M74HC245RM13TR operate reliably at 2.0V supply with full functionality?

Yes - the M74HC245RM13TR is fully specified from 2.0V to 6.0V. At 2.0V, VIH = 1.5V (min), VOL = 0.1V (max at 20µA), and tPLH/tPHL ≤135ns. It retains all logic functions, 3-state control, and noise immunity, making it suitable for ultra-low-voltage battery-powered systems.

Is there a risk of bus contention if both DIR and G are changed simultaneously?

No bus contention occurs because G has priority over DIR: when G = HIGH, all outputs enter high-impedance regardless of DIR state. The truth table confirms that output enable is independent of direction control, eliminating race conditions during mode transitions in real-time systems.

Does the M74HC245RM13TR require external pull-up or pull-down resistors on floating bus lines?

Yes - the datasheet explicitly states: "All floating bus terminals during High Z State must be held HIGH or LOW." Unbiased floating lines risk undefined logic states, increased power consumption, and potential shoot-through current. Use 10kΩ–100kΩ bias resistors tied to VCC or GND based on system default bus state requirements.