STMicroelectronics M74HC245TTR

Overview

M74HC245TTR from STMicroelectronics is an octal non-inverting bus transceiver with 3-state outputs, designed for bidirectional asynchronous data bus communication between two independent systems. It features directional control (DIR), output enable (G), symmetrical drive strength (|IOH| = IOL ≥ 6 mA), propagation delay of 10 ns (typ. at VCC = 6 V), and operates across 2 V to 6 V supply range. Used in industrial control backplanes and microcontroller peripheral expansion interfaces.

For engineers reviewing the M74HC245TTR datasheet, M74HC245TTR pinout, M74HC245TTR application, or M74HC245TTR equivalent, key selection criteria include 3-state isolation timing (tPZL/tPLZ ≤ 46 ns max), wide VCC range compatibility, high noise immunity (VNIH/VNIL ≥ 28% VCC), and TSSOP-20 package suitability for space-constrained PCB layouts.

Technical Context

The M74HC245TTR implements a dual-bus bidirectional interface using CMOS silicon gate C2MOS technology, with DIR input selecting data flow direction (A→B or B→A) and active-low G enabling/disabling all outputs into high-impedance state. All inputs include ESD and transient voltage protection circuits.

Its balanced propagation delays (tPLH ≅ tPHL) and symmetrical output impedance ensure minimal skew in multi-bit parallel transfers. The device supports operation from -55°C to +125°C with guaranteed DC parameters including VIH ≥ 3.15 V (at VCC = 4.5 V) and VOL ≤ 0.40 V (at IO = 6.0 mA).

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5 mm × 4.4 mm body, 0.65 mm pitch, 1.2 mm 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 74VHC245MTCX, the M74HC245TTR delivers the fastest propagation (10 ns typ.), highest drive strength (6 mA min.), and widest operating voltage (2–6 V), making it optimal for mixed-voltage industrial backplanes demanding timing precision and robustness.

Availability

M74HC245TTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, microcontroller peripheral expansion, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HC245TTR 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 management ICs with vertical manufacturing capabilities.

The M74HC245TTR belongs to ST's high-speed CMOS logic family, engineered for reliable bidirectional bus interfacing in harsh environments where timing accuracy, noise resilience, and long-term supply stability are critical.

FAQ

What is the maximum clock frequency supported by M74HC245TTR?

The M74HC245TTR is not a clocked device and has no internal clock; its usable data rate depends on propagation delay and system setup/hold timing. With tPD = 10 ns (typ.) and tPZL/tPLZ ≤ 46 ns, it supports reliable bus toggling up to approximately 50 MHz in well-designed synchronous interfaces using external clocking.

Can M74HC245TTR operate at 3.3 V supply?

Yes - the M74HC245TTR is fully specified from VCC = 2 V to 6 V, including 3.3 V. At 3.3 V, VIH = 2.31 V (min.), VOL ≤ 0.33 V (at 6 mA), and tPD ≈ 18 ns (max.), making it compatible with standard 3.3 V CMOS logic families without level translation.

Is the TSSOP-20 package of M74HC245TTR lead-free and RoHS compliant?

Yes - the M74HC245TTR in TSSOP-20 packaging is manufactured per STMicroelectronics' ECOPACK® standards, meeting RoHS Directive 2011/65/EU and being lead-free, halogen-free, and compliant with JEDEC J-STD-020 moisture sensitivity level 1 (MSL1) for unlimited floor life.

How does the DIR pin interact with the G (enable) pin?

The DIR pin controls data direction only when G is asserted LOW; when G is HIGH, both A and B ports enter high-impedance state regardless of DIR state. This prioritized enable logic ensures safe bus isolation before direction changes, preventing momentary contention during mode transitions.