Texas Instruments SN74ACT245DWR

Overview

SN74ACT245DWR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data bus communication between 5-V logic domains. It operates from 4.5 V to 5.5 V, supports TTL-compatible inputs up to 5.5 V, delivers ≤8 ns propagation delay at 5 V, and features independent direction (DIR) and output-enable (OE) controls - enabling use in industrial I/O expansion and legacy bus bridging applications.

For engineers reviewing the SN74ACT245DWR datasheet, SN74ACT245DWR pinout, SN74ACT245DWR application, or SN74ACT245DWR equivalent, key selection criteria include its SOIC-20 package, 24 mA output drive capability, 3.7 V VOH minimum at 4.5 V VCC, 0.44 V VOL maximum under 24 mA load, and guaranteed operation across –40°C to +85°C industrial temperature range.

Technical Context

The SN74ACT245DWR implements a dual-bus transceiver architecture with noninverting data flow controlled by DIR and OE pins. Its function table defines three operational states: A→B transfer (DIR = H, OE = L), B→A transfer (DIR = L, OE = L), and high-impedance isolation (OE = H). The device uses ACT (Advanced CMOS TTL-compatible) logic, ensuring compatibility with both CMOS and TTL input thresholds while maintaining low power consumption.

It features overvoltage-tolerant inputs (up to 5.5 V regardless of VCC), balanced output drive (±24 mA), and slow edge rates to suppress output ringing - critical for noise-sensitive industrial and pro-audio signal routing. Thermal resistance (RθJA) is 98.6°C/W in the DW (SOIC-20) package, supporting reliable operation without forced airflow in typical PCB layouts.

Key Specifications

Pinout & Package

SN74ACT245DWR is housed in a 20-pin SOIC (DW) package measuring 12.8 mm × 10.3 mm (body: 12.8 mm × 7.5 mm), RoHS-compliant with NIPDAU lead finish and MSL Level-1 rating (260°C reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245A and SN74AHCT245, the SN74ACT245DWR uniquely balances 5-V robustness, overvoltage-tolerant inputs, and industrial temperature support - making it the preferred choice for legacy-system upgrades and mixed-voltage industrial interfaces where reliability trumps raw speed.

Availability

SN74ACT245DWR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, pro audio digital bus interface, and factory automation backplane applications requiring stable component supply and long-term lifecycle assurance.

Supply support for SN74ACT245DWR 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 specializing in analog, embedded processing, and logic solutions, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74ACT245DWR belongs to TI's legacy ACT logic family, engineered for robust 5-V bus interfacing in harsh industrial environments - emphasizing noise immunity, voltage tolerance, and thermal stability over ultra-high speed.

FAQ

What is the maximum output current per pin for SN74ACT245DWR?

The SN74ACT245DWR supports ±24 mA DC output current per pin at VCC = 4.5 V or 5.5 V, as specified in Section 5.3 Recommended Operating Conditions. This rating ensures reliable driving of multiple TTL loads or moderate-capacitance buses. Exceeding this value risks exceeding absolute maximum ratings and may cause output voltage degradation or thermal stress. Always verify total package current limits (±200 mA continuous through VCC/GND) in high-utilization scenarios.

Does SN74ACT245DWR support mixed-voltage operation between A and B ports?

No - the SN74ACT245DWR does not support true mixed-voltage operation. Both A and B ports share the same VCC supply and operate at identical logic thresholds. However, its inputs tolerate up to 5.5 V regardless of VCC (e.g., VCC = 4.5 V), enabling safe connection to 5-V sources in systems with regulated 4.5–5.5 V rails. Separate voltage domains require external level-shifting circuitry.

What is the recommended bypass capacitor for SN74ACT245DWR?

Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible (<3 mm) to the VCC pin (pin 20) of the SN74ACT245DWR. This provides effective high-frequency decoupling for transient current demands during simultaneous switching of all eight outputs. For systems with multiple logic devices, paralleling a 1 µF tantalum or aluminum electrolytic capacitor nearby improves low-frequency stability.

Can SN74ACT245DWR be used in hot-swap applications?

The SN74ACT245DWR is not specifically qualified for hot-swap operation. While its overvoltage-tolerant inputs (up to 5.5 V) and high-impedance state on OE = H provide partial protection, it lacks built-in current limiting, slew-rate control for insertion transients, or rail-to-rail fault detection. For hot-swap systems, add series current-limiting resistors and TVS diodes on all I/O lines, and ensure OE is held high until power stabilization is confirmed.

What is the thermal resistance (RθJA) of SN74ACT245DWR in its SOIC package?

The SN74ACT245DWR in the DW (SOIC-20) package has a junction-to-ambient thermal resistance (RθJA) of 98.6°C/W, as documented in Section 5.4 Thermal Information. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad). Actual thermal performance improves with additional copper pour, thermal vias, or heatsinking - critical for sustained 24 mA loading across all channels at +85°C ambient.