STMicroelectronics M74HCT245TTR

Overview

M74HCT245TTR from STMicroelectronics is an octal bus transceiver with non-inverting 3-state outputs, designed for bidirectional asynchronous data bus interfacing. It features directional control (DIR), output enable (G), symmetrical drive strength (±6 mA), propagation delay of 13 ns (typ. at VCC = 4.5 V), and TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V). Used in industrial backplane interfaces and legacy system bus isolation.

For engineers reviewing the M74HCT245TTR datasheet, M74HCT245TTR pinout, M74HCT245TTR application, or M74HCT245TTR equivalent, key selection criteria include bidirectional data flow control, 3-state bus isolation timing, high-impedance leakage (<5 µA), and TSSOP-20 package compatibility with space-constrained PCB layouts.

Technical Context

The M74HCT245TTR implements a dual-bus, directionally gated transceiver architecture using silicon gate C2MOS technology. Its DIR input selects A→B or B→A data flow, while G enables/disables all outputs into high-impedance state-critical for bus arbitration in shared-data systems.

It operates across -55°C to +125°C with supply voltage 4.5–5.5 V, delivers balanced tPLH/tPHL delays (≈13 ns typ.), and maintains symmetrical output impedance (|IOH| = |IOL| ≥ 6 mA), ensuring consistent signal integrity during both rising and falling transitions on either bus side.

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5 mm × 4.4 mm body, 0.65 mm pitch, 1.2 mm 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 SN74HCT245PWR and 74VHC245FT, the M74HCT245TTR offers superior quiescent current (4 µA) and extended temperature range (-55°C to +125°C), making it preferred for low-power, high-reliability industrial and automotive bus isolation where timing margin exceeds 13 ns.

Availability

M74HCT245TTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, and legacy microcontroller bus extension requiring stable component supply across extended temperature and long lifecycle programs.

Supply support for M74HCT245TTR 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, designing and manufacturing analog, digital, and mixed-signal ICs for industrial, automotive, and consumer markets.

The M74HCT245TTR belongs to ST's high-speed CMOS logic family, engineered specifically for robust, low-power bus interfacing in harsh-environment embedded systems.

FAQ

What is the maximum capacitive load the M74HCT245TTR can drive reliably?

The M74HCT245TTR is characterized up to 150 pF load capacitance per output, with propagation delay increasing from 13 ns (CL = 50 pF) to 38 ns (CL = 150 pF) at VCC = 4.5 V. Driving beyond 150 pF risks timing violations and increased transition time; external series termination or buffer staging is recommended for heavier loads.

Can the DIR and G inputs be tied together for unidirectional operation?

Yes - tying DIR and G together (e.g., to a single control line) configures the device as a unidirectional buffer with enable, but this eliminates independent direction control. In that mode, logic HIGH enables A→B flow only; logic LOW forces all outputs to high-Z. This simplifies control logic at the cost of bidirectional flexibility.

Does the M74HCT245TTR support hot insertion or live bus swapping?

No - while the high-impedance state isolates buses, the M74HCT245TTR lacks built-in bus-hold or power-up/down protection. Hot insertion may cause transient glitches or latch-up if VCC ramps before control signals stabilize. External sequencing or dedicated hot-swap controllers are required for safe live insertion.

Is there a version of this transceiver with inverted outputs?

No - the M74HCT245TTR provides non-inverting outputs only. STMicroelectronics offers the M74HCT244TTR (octal buffer, non-inverting) and M74HCT240TTR (octal inverter buffer) for unidirectional cases, but no pin-compatible inverted-transceiver variant exists in the M74HCT series.