Texas Instruments SN74ACT245DWRG4

Overview

SN74ACT245DWRG4 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 at 4.5 V to 5.5 V, supports TTL-compatible inputs up to 5.5 V, delivers 8 ns max propagation delay at 5 V, and features direction control (DIR) and output enable (OE) pins for flexible bus isolation - used in industrial video signage interfaces and factory automation backplanes.

For engineers reviewing the SN74ACT245DWRG4 datasheet, SN74ACT245DWRG4 pinout, SN74ACT245DWRG4 application, or SN74ACT245DWRG4 equivalent, key selection criteria include its SOIC-20 package compatibility, 24 mA output drive capability, 3.7 V min VOH at 4.5 V VCC, thermal resistance of 98.6 °C/W, and functional mode behavior under OE/DIR logic combinations.

Technical Context

The SN74ACT245DWRG4 implements a dual-bus transceiver architecture with noninverting data flow controlled by DIR and enabled/disabled via OE. Its CMOS design provides balanced output drive and slow edge rates to minimize ringing on lightly loaded buses.

It supports bidirectional data transfer between A and B ports with high-impedance isolation when OE is high, and operates across –40°C to +85°C ambient temperature. Input voltage tolerance extends to 5.5 V regardless of VCC level, enabling safe interfacing with mixed-voltage systems.

Key Specifications

Pinout & Package

SN74ACT245DWRG4 uses 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 moisture sensitivity level 1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245APWR and 74ACT245SCX, the SN74ACT245DWRG4 uniquely supports legacy 5-V-only infrastructure without voltage translation, offers proven thermal margin in SOIC packaging, and maintains full pin-and-function compatibility with established TI-based designs.

Availability

SN74ACT245DWRG4 is available at Aetrix Electronics and suitable for factory automation backplanes, video signage controllers, and appliance mainboard communication requiring stable component supply across extended product lifecycles.

Supply support for SN74ACT245DWRG4 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 for industrial, automotive, and communications markets.

The SN74ACT245 series was developed to provide robust, low-ringing bidirectional bus interfacing in noise-sensitive 5-V industrial control systems - emphasizing reliability, wide supply tolerance, and ease of integration.

FAQ

What is the maximum operating temperature for SN74ACT245DWRG4?

The SN74ACT245DWRG4 is rated for operation from –40°C to +85°C ambient temperature. This range is specified in the Recommended Operating Conditions table and validated across all electrical parameters including VOH, VOL, and tpd. The device's 98.6 °C/W junction-to-ambient thermal resistance ensures safe operation within this envelope when power dissipation remains below ~360 mW. Exceeding +85°C ambient may cause parametric drift or latch-up risk.

Does SN74ACT245DWRG4 support mixed-voltage interfacing?

Yes, SN74ACT245DWRG4 supports mixed-voltage interfacing through its overvoltage-tolerant inputs: all A and B port pins accept voltages up to 5.5 V regardless of VCC level (4.5–5.5 V). This allows safe connection to 5-V peripherals even when VCC is at minimum 4.5 V, eliminating external clamping diodes. However, output levels remain referenced to VCC, so driving true 3.3-V logic directly is not supported without level translation.

How should the OE and DIR pins be biased during power-up?

During power-up, OE must be held high (via pullup to VCC) to ensure all A/B ports remain in high-impedance state until firmware initializes direction and enable control. DIR can float or be pulled to either rail depending on default data flow preference, but TI recommends tying OE to VCC through a ≤10-kΩ resistor to guarantee isolation before system initialization. Failure to bias OE correctly risks bus contention and excessive current draw.

What is the recommended bypass capacitor for SN74ACT245DWRG4?

Texas Instruments specifies a 0.1 µF ceramic capacitor placed as close as possible (<3 mm) to the VCC pin (pin 20) and GND (pin 10) to suppress high-frequency supply noise. For systems with multiple VCC-connected devices, parallel placement of 0.1 µF and 1 µF capacitors is recommended to cover broader noise spectra. The capacitor must be X7R or better dielectric with low ESL, mounted directly on the same PCB layer as the SN74ACT245DWRG4 footprint.

Can SN74ACT245DWRG4 replace SN74LS245 in existing designs?

SN74ACT245DWRG4 can replace SN74LS245 in most 5-V systems due to identical pinout, function table, and DC logic thresholds (VIH = 2.0 V, VIL = 0.8 V). Key advantages include lower power consumption (ICC < 40 µA vs. LS's ~30 mA), higher noise immunity, and improved output drive (±24 mA vs. LS's ±20 mA). However, verify layout for reduced ground bounce and ensure OE/DIR timing margins accommodate ACT's faster tpd (8 ns vs. LS's 12–25 ns).