Texas Instruments SN74AC245DGSR

Overview

SN74AC245DGSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data bus communication between A and B ports. It operates across 2V–6V VCC, accepts inputs up to 6V, delivers ≤7ns propagation delay at 5V, and supports industrial temperature range (–40°C to +85°C). It enables isolated bus control in mixed-voltage system interconnects.

For engineers reviewing the SN74AC245DGSR datasheet, SN74AC245DGSR pinout, SN74AC245DGSR application, or SN74AC245DGSR equivalent, key selection criteria include voltage-level translation capability, direction-control logic behavior, 3-state output isolation timing, and VSSOP-20 package compatibility with high-density PCB layouts.

Technical Context

The SN74AC245DGSR implements dual 8-bit bidirectional data paths controlled by DIR (direction) and OE (output enable) inputs. Its CMOS design ensures balanced drive strength and slow edge rates to suppress output ringing-critical for noise-sensitive audio/video interfaces.

It functions in three modes: A→B data flow (DIR = HIGH), B→A data flow (DIR = LOW), or high-impedance isolation (OE = HIGH). All I/O pins are 6V-tolerant regardless of VCC, enabling safe interfacing with higher-voltage logic domains without level shifters.

Key Specifications

Pinout & Package

VSSOP-20 (DGS) package: 5.1 mm × 4.9 mm body size, 0.5 mm pitch, exposed thermal pad optional, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245A and SN74ALVC245, the SN74AC245DGSR uniquely supports true 5 V ↔ 3.3 V bidirectional translation without external components, making it optimal for retrofitting legacy industrial hardware with modern low-voltage controllers.

Availability

SN74AC245DGSR is available at Aetrix Electronics and suitable for pro audio digital bus interface, video signage data bridging, and smart appliance control hub applications requiring stable component supply across extended product lifecycles.

Supply support for SN74AC245DGSR 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 connectivity technologies with over 90 years of innovation in industrial and automotive electronics.

The SN74AC245DGSR belongs to TI's AC-series logic family, engineered for robust mixed-voltage interoperability in noise-sensitive real-time control and media infrastructure systems.

FAQ

What is the maximum operating voltage for SN74AC245DGSR I/O pins?

The SN74AC245DGSR I/O pins (A1–A8, B1–B8, DIR, OE) tolerate up to 6 V regardless of VCC level, enabling safe interfacing with 5 V buses even when powered from 3.3 V. This eliminates external clamping diodes in mixed-voltage designs and is confirmed in Section 5.3 Recommended Operating Conditions and Absolute Maximum Ratings of the official datasheet.

Does SN74AC245DGSR support bidirectional data flow on the same pins?

Yes, SN74AC245DGSR supports true bidirectional data flow: A1–A8 and B1–B8 are fully bidirectional I/Os. Direction is controlled solely by the DIR pin-HIGH enables A→B transfer, LOW enables B→A transfer. This behavior is defined in Table 7-1 (Function Table) and verified in Figure 4-1 pin configuration diagrams for the DGS package.

What is the propagation delay of SN74AC245DGSR at 3.3 V supply?

At VCC = 3.3 V, the SN74AC245DGSR exhibits typical propagation delay of 5 ns (tPLH/tPHL) with maximum 9 ns, as specified in Section 5.6 Switching Characteristics. This performance is measured under standard load conditions (CL = 50 pF) and ensures reliable timing margin in 3.3 V system backplanes operating below 100 MHz.

How does the OE pin function in SN74AC245DGSR?

The OE (output enable) pin on SN74AC245DGSR is active-low: when OE = LOW, the transceiver operates normally; when OE = HIGH, all A and B port pins enter high-impedance (3-state) mode, effectively isolating both buses. This isolation is critical during power sequencing and hot-swap operations, and is explicitly detailed in Section 7.1 Overview and Table 7-1.

Is SN74AC245DGSR compatible with VSSOP-20 PCB footprints from other manufacturers?

Yes, SN74AC245DGSR uses the industry-standard VSSOP-20 (DGS) package with 0.5 mm pitch and 5.1 mm × 4.9 mm body dimensions, matching JEDEC MO-178AC specifications. Its pinout (Figure 4-1) and thermal pad configuration align with common VSSOP-20 land patterns, enabling drop-in replacement in existing designs using compatible VSSOP logic devices.