Texas Instruments SN74BCT245DW

Overview

SN74BCT245DW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in industrial control and memory address buffering applications. It operates at 4.5–5.5 V, supports 64 mA sink current on B-port outputs, and features direction (DIR) and output-enable (OE) control logic with propagation delays as low as 1 ns.

For engineers reviewing the SN74BCT245DW datasheet, SN74BCT245DW pinout, SN74BCT245DW application, or SN74BCT245DW equivalent, key selection criteria include 3-state isolation capability, TTL-compatible input thresholds, high-current B-port drive strength, thermal performance in SOIC-DW package (θ_JA = 58°C/W), and compatibility with legacy 5-V bus systems requiring robust noise immunity and ESD protection exceeding 2000-V HBM.

Technical Context

The SN74BCT245DW implements dual 8-bit bidirectional data paths controlled by DIR to select A→B or B→A flow, while OE independently enables or disables all outputs into high-impedance state. Its BCT (Bipolar-CMOS-TTL) process delivers TTL-level input compatibility and CMOS-level power efficiency.

It supports mixed-voltage interfacing only within 5-V domain: inputs tolerate –0.5 V to 7 V, but I/O ports are rated for –0.5 V to 5.5 V. Absolute maximum ratings prohibit operation outside 4.5–5.5 V supply range during normal use, and unused inputs must be tied to V_CC or GND per TI SCBA004 guidance.

Key Specifications

Pinout & Package

SN74BCT245DW uses a 20-pin SOIC (DW) package measuring 7.5 mm × 12.8 mm × 2.65 mm (max height), with 1.27 mm lead pitch and gull-wing terminations compatible with standard reflow profiles (MSL Level-1).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74BCT245DW, SN74LVC245A offers lower power but lacks 5-V tolerance and drive strength, while SN74ABT245 delivers superior speed and noise rejection in the same 5-V domain-making it a drop-in performance upgrade where available.

Availability

SN74BCT245DW is available at Aetrix Electronics and suitable for industrial control backplanes, legacy memory subsystems, and parallel interface designs requiring stable component supply and long-term obsolescence management.

Supply support for SN74BCT245DW 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

Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74BCT245DW belongs to TI's legacy BCT logic family, engineered specifically for robust 5-V bus interfacing in industrial automation and retro-compatibility applications where TTL signal integrity and high-current drive are essential.

FAQ

What is the operating temperature range for SN74BCT245DW?

The SN74BCT245DW is specified for commercial operation from 0°C to +70°C. This range aligns with its SOIC-DW packaging and intended use in non-military, non-automotive industrial and computing applications. It is not rated for extended temperature ranges like the SN54BCT245 (–55°C to +125°C), and operation outside 0–70°C may result in parametric failure or reduced reliability.

Can SN74BCT245DW interface directly with 3.3-V logic?

No, SN74BCT245DW is not 3.3-V tolerant. Its inputs are TTL-compatible (V_IH = 2.0 V min), but outputs swing rail-to-rail at 5 V, and I/O ports are rated only to 5.5 V. Direct connection to 3.3-V CMOS inputs risks overvoltage damage or excessive input leakage. Level-shifting circuitry or a 3.3-V–compatible transceiver such as SN74LVC245A is required for mixed-voltage systems.

Is SN74BCT245DW pin-compatible with SN74ABT245?

Yes, SN74BCT245DW and SN74ABT245 share identical SOIC-DW packaging, pinout, and functional logic (DIR/OE control, 3-state outputs). The ABT variant improves propagation delay and noise immunity while maintaining full electrical and mechanical compatibility - making it a validated drop-in upgrade for new designs where enhanced timing or EMC performance is needed.

What is the maximum capacitive load SN74BCT245DW can drive reliably?

SN74BCT245DW is characterized with CL = 50 pF in switching tests, and typical power dissipation curves extend to 150 pF. For reliable operation at full speed (≤7 ns propagation), total load per output should remain ≤50 pF. At higher capacitance (e.g., 100–150 pF), propagation delay increases and edge rates degrade - requiring derating of maximum frequency or addition of series termination resistors.

Does SN74BCT245DW require external pull-up or pull-down resistors on DIR or OE?

Yes - per TI application report SCBA004, all unused inputs including DIR and OE must be actively held at V_CC or GND. Floating control inputs cause undefined output states, increased ICC, and potential oscillation. A 10-kΩ pull-up to V_CC is recommended for OE (to ensure default isolation) and for DIR if fixed-direction operation is required; values must be verified against board leakage and noise margins.