Texas Instruments PCA9545ADGVRG4

Overview

PCA9545ADGVRG4 from Texas Instruments is a low-voltage, 4-channel bidirectional I²C/SMBus switch with interrupt logic and active-low reset. It routes one upstream SCL/SDA pair to four independently selectable downstream SCn/SDn channels, supports voltage-level translation across 1.8 V, 2.5 V, 3.3 V, and 5 V buses, and operates from 2.3 V to 5.5 V supply. It enables conflict-free communication among multiple identical I²C slaves-e.g., temperature sensors-in server and telecom switching equipment.

For engineers reviewing the PCA9545ADGVRG4 datasheet, PCA9545ADGVRG4 pinout, PCA9545ADGVRG4 application, or PCA9545ADGVRG4 equivalent, key selection considerations include channel-selectable I²C fanout, per-channel interrupt aggregation (INT3–INT0 → INT), active-low hardware reset recovery from bus lockup, 400-kHz Fast-Mode support, and 5.5-V-tolerant I/O with no glitch on power-up.

Technical Context

The PCA9545ADGVRG4 implements four independent analog pass-gate switches controlled by an 8-bit I²C-accessible register, where bits B0–B3 enable/disable channels 0–3. Its interrupt logic performs a wired-AND of four open-drain INTn inputs into a single active-low INT output, with status bits (B4–B7) readable in the same register.

Reset functionality is dual-path: an external active-low RESET signal (t_WL ≥ 6 ns) or internal power-on reset (V_POR = 1.6–2.1 V) forces all channels deselected and clears the control register. Switch R_ON is 5–45 Ω depending on V_CC, enabling low-loss bidirectional signal translation without direction control pins.

Key Specifications

Pinout & Package

TSSOP-20 package (6.50 mm × 4.40 mm), lead pitch 0.65 mm, RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C bus switching applications.

Compared with TCA9544APWR, PCA9545ADGVRG4 adds hardware reset and interrupt aggregation - critical for robust fault handling. Versus PCA9548ARGVR, it offers smaller footprint and lower quiescent current for 4-channel use cases, avoiding unnecessary complexity.

Availability

PCA9545ADGVRG4 is available at Aetrix Electronics and suitable for server baseboard management, telecom router control planes, and factory automation I/O hubs requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9545ADGVRG4 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 company delivering analog and embedded processing solutions, with leadership in interface, power management, and signal chain technologies.

The PCA9545ADGVRG4 belongs to TI's I²C switch and multiplexer product line, designed specifically to resolve I²C slave address conflicts, enable mixed-voltage interoperability, and simplify system-level bus management in dense embedded systems.

FAQ

What is the primary function of the PCA9545ADGVRG4 in an I²C system?

The PCA9545ADGVRG4 functions as a 4-channel bidirectional I²C bus switch that enables a single master to communicate with multiple isolated slave sub-buses. It resolves address conflicts by assigning each group of identical slaves (e.g., temperature sensors) to a dedicated channel, and supports voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V domains without external level shifters. This capability is built into the PCA9545ADGVRG4's pass-gate architecture and programmable control register.

How does the RESET pin on the PCA9545ADGVRG4 improve system reliability?

The active-low RESET pin on the PCA9545ADGVRG4 provides hardware-based recovery from I²C bus lockup conditions - for example, when a downstream slave holds SDA low indefinitely. Asserting RESET for ≥6 ns resets the internal state machine, deselects all channels, and clears the control register, restoring normal operation without cycling main power. This feature is integral to the PCA9545ADGVRG4's design for mission-critical infrastructure like servers and telecom routers.

Can the PCA9545ADGVRG4 translate between different I²C voltage levels, and how is this implemented?

Yes, the PCA9545ADGVRG4 supports voltage-level translation across 1.8 V, 2.5 V, 3.3 V, and 5 V I²C buses. It achieves this through its pass-gate switch architecture: each SCn/SDn channel uses external pull-up resistors tied to its local domain voltage, while the VCC pin sets the maximum pass-through voltage. The PCA9545ADGVRG4's 5.5-V-tolerant I/O ensures signal integrity across domains - no additional level-shifting ICs are needed in the PCA9545ADGVRG4-based design.

How does the interrupt logic of the PCA9545ADGVRG4 reduce software overhead?

The PCA9545ADGVRG4 reduces software overhead by aggregating four per-channel interrupt inputs (INT0–INT3) into a single active-low INT output via wired-AND logic, and mirroring interrupt status in bits B4–B7 of its I²C-accessible control register. When any downstream device asserts INTn, the master receives one interrupt signal and reads the PCA9545ADGVRG4's register to identify the source channel - eliminating the need for polling or GPIO expansion. This behavior is inherent to the PCA9545ADGVRG4's interrupt architecture.

What are the key differences between the PCA9545ADGVRG4 and the TCA9544APWR?

The PCA9545ADGVRG4 includes an active-low RESET pin and aggregated INT output (wired-AND of INT0–INT3), while the TCA9544APWR lacks both features - it offers only individual INT0–INT3 outputs and no hardware reset. As a result, the PCA9545ADGVRG4 enables autonomous bus recovery and faster interrupt source identification, making it superior for fault-resilient applications. Both share identical channel-switching functionality and pin compatibility, but these distinctions are fundamental to the PCA9545ADGVRG4's value proposition.