STMicroelectronics 74VHC245TTR

Overview

74VHC245TTR from STMicroelectronics is an advanced high-speed CMOS octal bus transceiver (3-state) with directional control and output enable, operating from 2V to 5.5V supply. It provides bidirectional data flow between two 8-bit buses, features 4.0 ns typical propagation delay at 5V, ±8 mA symmetrical drive strength, and 2 kV ESD protection on all I/O pins. Used in level-shifting and bus-isolation applications within industrial microcontroller interfaces.

For engineers reviewing the 74VHC245TTR datasheet, 74VHC245TTR pinout, 74VHC245TTR application, or 74VHC245TTR equivalent, key selection criteria include directional control logic (DIR), 3-state enable timing (tPZL/tPLZ), VCC operating range (2–5.5 V), symmetrical output drive (|IOH| = IOL ≥ 8 mA), and TSSOP-20 package compatibility with space-constrained PCB layouts.

Technical Context

The 74VHC245TTR implements a dual-bus, directionally controlled transceiver architecture where DIR selects data flow direction (A→B or B→A), while G enables or disables all outputs into high-impedance state. Its sub-micron C2MOS process ensures low dynamic power and latch-up immunity.

It supports asynchronous bidirectional communication without internal clocking or handshaking. All inputs tolerate overvoltage up to VCC + 0.5 V, and outputs maintain rail-to-rail voltage compliance under load, enabling robust interfacing across mixed-voltage domains (e.g., 3.3 V MCU ↔ 5 V peripheral bus).

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5 mm × 4.4 mm body, 0.65 mm pitch, exposed pad not present, JEDEC MO-153 compliant.

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 74VHC245TTR uniquely balances wide VCC range (2–5.5 V), extended temperature support (-55°C to +125°C), and sub-5 ns speed-making it optimal for industrial and automotive bus isolation where voltage flexibility and ruggedness are prioritized over absolute minimum propagation delay.

Availability

74VHC245TTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, embedded memory expansion subsystems, and automotive body control modules requiring stable component supply across extended temperature ranges and mixed-voltage interfaces.

Supply support for 74VHC245TTR 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 with emphasis on reliability, longevity, and automotive-grade qualification.

The 74VHC series targets high-speed, low-power CMOS logic replacement for legacy TTL, emphasizing robustness in harsh environments and seamless integration into mixed-voltage digital systems.

FAQ

What is the maximum recommended operating frequency for 74VHC245TTR in a 5 V system?

The 74VHC245TTR has a typical propagation delay of 4.0 ns at VCC = 5 V, supporting reliable operation up to approximately 25 MHz in worst-case bus timing (accounting for setup/hold and enable/disable delays). System-level frequency is constrained by board trace length, load capacitance, and driver strength-not by internal clocking, as it is asynchronous.

Can 74VHC245TTR safely interface a 3.3 V microcontroller with a 5 V peripheral without level shifters?

Yes-its inputs tolerate VI up to VCC + 0.5 V, and outputs swing rail-to-rail. When powered at 5 V, it accepts 3.3 V logic-high inputs (VIH = 0.7×5 = 3.5 V min, so 3.3 V is marginal but functional with noise margin); when powered at 3.3 V, outputs meet 5 V TTL thresholds only if peripheral inputs are 3.3 V tolerant. For guaranteed 5 V peripheral drive, use 5 V VCC with appropriate input clamping.

Is the TSSOP-20 package of 74VHC245TTR RoHS-compliant and lead-free?

Yes-the 74VHC245TTR is manufactured in a RoHS-compliant, lead-free TSSOP-20 package per STMicroelectronics' ECOPACK2 specifications. The device carries the "E" suffix in ordering codes indicating lead-free finish, and its JEDEC MO-153 mechanical drawing confirms Pb-free terminal plating (matte tin).

How does the DIR and G pin interaction affect bus contention risk?

Bus contention is prevented by strict priority: G is dominant-when G = HIGH, all A and B pins enter high-impedance regardless of DIR state. Only when G = LOW does DIR determine direction. This ensures no simultaneous drive from both buses, eliminating shoot-through current. External pull-downs on G are recommended in systems where power sequencing may leave G floating during startup.