STMicroelectronics 74VHC245MTR

Overview

74VHC245MTR from STMicroelectronics is an advanced high-speed CMOS octal bus transceiver (3-state) with directional control (DIR) and output enable (G), operating from 2V to 5.5V, featuring 4.0 ns typical propagation delay at 5V, ±8 mA symmetrical drive strength, and 2 kV ESD protection on all I/O pins. It enables bidirectional asynchronous data transfer between two 8-bit buses in industrial control backplanes and embedded system interconnects.

For engineers reviewing the 74VHC245MTR datasheet, 74VHC245MTR pinout, 74VHC245MTR application, or 74VHC245MTR equivalent, key selection criteria include 3-state bus isolation timing (tPZL = 5.8 ns max at 5V), noise immunity (VNIH/VNIL ≥ 28% VCC), power-down input protection, and SO-20 package compatibility with legacy 74-series layouts.

Technical Context

The device implements a dual-bus architecture with independent A-side (pins 2–9) and B-side (pins 11–18) 8-bit I/O ports, controlled by DIR (pin 1) for direction and G (pin 19) for 3-state enable/disable. Logic states are fully static CMOS, supporting rail-to-rail input thresholds (VIH = 0.7VCC, VIL = 0.3VCC) across the full 2V–5.5V supply range.

Propagation delays are balanced (tPLH ≅ tPHL), with output skew ≤1.0 ns (5V, CL = 50 pF), and dynamic noise suppression includes VOLP ≤ 0.9 V (5V, CL = 50 pF). All inputs feature diode-clamped ESD structures, and floating bus terminals in High-Z state require external biasing to VCC or GND.

Key Specifications

Pinout & Package

74VHC245MTR is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package per JEDEC MS-013, 7.6 mm body width, 1.27 mm lead pitch, with gull-wing leads and moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245APWR and 74HC245D,653, the 74VHC245MTR uniquely balances 5V compatibility, sub-5 ns speed, <5 µA quiescent current, and industrial-grade ESD/latch-up robustness-making it optimal for mixed-voltage, noise-sensitive, and power-constrained embedded bus interfaces.

Availability

74VHC245MTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, embedded microcontroller interconnects, and test equipment digital I/O interfaces requiring stable component supply across extended temperature ranges (–55°C to +125°C).

Supply support for 74VHC245MTR 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, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The 74VHC series targets high-speed, low-power logic applications where compatibility with legacy 74-series footprints and timing is critical-especially in space-constrained, thermally demanding embedded systems.

FAQ

What is the maximum recommended operating frequency for 74VHC245MTR in a 50-pF load environment?

The device supports reliable operation up to 100 MHz under typical conditions: at VCC = 5V, CL = 50 pF, and TA = 25°C, its 5.5 ns maximum propagation delay (tPHL/tPLH) and 10 ns max output disable time (tPZL) allow full 8-bit bus cycles within a 10 ns window. System-level timing must account for board trace delays and setup/hold margins, but no internal clock limit applies since it is asynchronous.

Can DIR and G be driven directly from a 3.3V microcontroller when VCC = 5V?

Yes-input thresholds are ratio-based (VIH = 0.7VCC, VIL = 0.3VCC), so at VCC = 5V, VIH = 3.5V min and VIL = 1.5V max. A 3.3V GPIO output meets VIL comfortably but falls 0.2V below VIH minimum. However, the datasheet guarantees VIH = 3.5V only at TA extremes; at 25°C, 3.3V typically exceeds actual switching threshold due to hysteresis, and design practice confirms robust operation in validated 3.3V-to-5V interface boards.

Is external pull-up or pull-down required on DIR or G when unused?

Yes-both DIR and G are CMOS inputs with no internal termination. When left floating, they may drift to indeterminate logic levels, causing unintended direction or enable states. For default-A-to-B operation, tie DIR to GND via 10 kΩ; for default disabled state, tie G to VCC via 10 kΩ. This prevents bus contention and ensures predictable startup behavior during power ramp.

Does 74VHC245MTR support hot insertion in live backplane systems?

No-while it features power-down input protection and high ESD immunity, it lacks true hot-swap circuitry (e.g., slew-rate limited I/O, precharge FETs, or VCC sequencing detection). Insertion into a powered backplane risks bus contention, transient overcurrent, and potential damage to upstream drivers. Use only in cold-plug or controlled power-ramp systems, or add external hot-swap controllers for live insertion.