Texas Instruments PCA9545ARGYRG4

Overview

PCA9545ARGYRG4 from Texas Instruments is a low-voltage, quad-channel I²C and SMBus switch with interrupt logic and active-low reset. It functions as a bidirectional translating multiplexer that routes one upstream SCL/SDA pair to any combination of four downstream SCn/SDn channels (0–3), supports voltage-level translation across 1.8-V, 2.5-V, 3.3-V, and 5-V domains, and features four active-low interrupt inputs (INT0–INT3) with a shared open-drain INT output - used in server motherboard I/O expansion and multi-sensor systems where slave address conflicts occur.

For engineers reviewing the PCA9545ARGYRG4 datasheet, PCA9545ARGYRG4 pinout, PCA9545ARGYRG4 application, or PCA9545ARGYRG4 equivalent, this device is selected for designs requiring dynamic I²C bus segmentation, fault-tolerant interrupt aggregation, hot-insertion support, and robust reset recovery without PCB layout changes.

Technical Context

The PCA9545ARGYRG4 implements a register-controlled, 4-channel analog switch matrix with independent channel enable/disable via its 8-bit control register (bits B0–B3). Its interrupt logic performs a wired-AND of INT0–INT3 onto the open-drain INT pin, while preserving interrupt status in bits 4–7 of the same register for master-side polling.

Its reset architecture includes both an external active-low RESET input (t_WL = 6 ns min) and internal power-on reset (VPOR = 1.6 V to 2.1 V), both forcing all channels deselected and clearing the control register. Switch pass-gates are constructed to limit maximum passed voltage by VCC, enabling safe level translation without external clamping.

Key Specifications

Pinout & Package

TSSOP-20 (RGY) package: 6.50 mm × 4.40 mm body, 0.65 mm pitch, thermally enhanced with θ_JA = 47 °C/W - suitable for dense PCB layouts with thermal constraints.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9545A, PCA9545ARGYRG4 offers identical electrical performance but lacks extended temperature qualification; compared with PCA9544A, it adds full 4-channel capability and interrupt support for the fourth channel - making it the only option for scalable multi-sensor I²C architectures requiring four independent domains.

Availability

PCA9545ARGYRG4 is available at Aetrix Electronics and suitable for server baseboard management, telecom router line-card control, and medical multi-sensor patient monitors requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for PCA9545ARGYRG4 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 headquartered in Dallas, Texas, designing and manufacturing analog and embedded processing chips for industrial, automotive, and communications markets.

The PCA9545ARGYRG4 belongs to TI's I²C switch and multiplexer product line, engineered specifically for reliable bus segmentation, interrupt consolidation, and voltage-domain bridging in high-density embedded systems with mixed-voltage peripherals.

FAQ

What is the primary function of the PCA9545ARGYRG4 in an I²C system?

The PCA9545ARGYRG4 functions as a quad-channel bidirectional I²C bus switch that routes a single upstream master SCL/SDA pair to any combination of four downstream slave buses (SC0/SD0 through SC3/SD3). It resolves slave address conflicts, enables voltage-level translation between different I²C domains (1.8 V to 5 V), and aggregates interrupts from all four channels onto a single INT output - simplifying master-side interrupt handling and bus resource management in complex embedded systems.

How does the PCA9545ARGYRG4 handle bus faults such as a stuck-low SCL line?

The PCA9545ARGYRG4 recovers from stuck-bus conditions via its active-low RESET input: asserting RESET for ≥6 ns forces the internal I²C state machine and control register to reset, deselecting all channels and releasing all downstream SDA/SCn lines. This hardware reset avoids requiring a full power cycle. Additionally, an internal power-on reset (VPOR = 1.6–2.1 V) performs the same recovery when VCC ramps up, ensuring clean initialization during power-up sequences.

Can the PCA9545ARGYRG4 translate between different I²C voltage domains, and how is this implemented?

Yes, the PCA9545ARGYRG4 supports voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V I²C buses. Its pass-gate architecture uses VCC as the maximum allowable output voltage, so each downstream channel (SCn/SDn) can be pulled up to its own domain voltage using external resistors - e.g., 1.8-V pull-ups on SD0/SC0 and 5-V pull-ups on SD3/SC3. All I/O pins are 5.5-V tolerant, enabling safe interfacing without additional level-shifting components.

What is the role of the A0 and A1 pins on the PCA9545ARGYRG4?

The A0 and A1 pins on the PCA9545ARGYRG4 are hardware-configurable address inputs that set the device's 7-bit I²C slave address. They determine the two LSBs of the fixed base address 11100xx, allowing up to four PCA9545ARGYRG4 devices to coexist on the same I²C bus without address collision. Each pin must be hard-wired to either VCC or GND - no internal pull-ups exist, so external termination is mandatory for stable operation.

How does the interrupt logic work on the PCA9545ARGYRG4, and how does a system master identify which channel triggered it?

The PCA9545ARGYRG4 features four active-low interrupt inputs (INT0–INT3), one per downstream channel, whose signals are logically ANDed onto the open-drain INT output. When any INTn is asserted, INT goes low. To identify the source, the master reads the PCA9545ARGYRG4's 8-bit control register: bits 4–7 reflect the current state of INT0–INT3, respectively. A '1' in bit 4 indicates INT0 is active; the master then selects that channel to communicate with the triggering slave and clear the condition.