Texas Instruments PCA9545ARGYR

Overview

PCA9545ARGYR from Texas Instruments is a low-voltage 4-channel I²C and SMBus switch with interrupt logic and active-low reset. It functions as a bidirectional translating multiplexer, enabling one master to selectively route SCL/SDA signals to four independent downstream I²C buses (SC0/SD0–SC3/SD3), supports voltage-level translation across 1.8-V, 2.5-V, 3.3-V, and 5-V domains, and operates from 2.3 V to 5.5 V supply. It is used in server backplanes to resolve I²C slave address conflicts among identical temperature sensors.

For engineers reviewing the PCA9545ARGYR datasheet, PCA9545ARGYR pinout, PCA9545ARGYR application, or PCA9545ARGYR equivalent, key selection criteria include channel-selectable I²C routing, 400-kHz Fast-Mode support, integrated interrupt aggregation (INT0–INT3 → INT), active-low RESET recovery, and TSSOP-20 package compatibility with 6.5 mm × 4.4 mm footprint.

Technical Context

The PCA9545ARGYR implements four independent bidirectional pass-gate switches controlled via an 8-bit I²C-accessible control register. Channel selection is performed by writing to bits B0–B3; interrupt status from each downstream bus is read from bits B4–B7. The device uses no internal pull-ups on A0/A1, requiring external termination for address configuration (up to four devices per bus).

Its interrupt logic performs a wired-AND of INT0–INT3 onto open-drain INT output, while RESET asynchronously clears the control register and deselects all channels. Switch R_ON is 5 Ω (typ) at 2.3 V–2.7 V and 11 Ω (max) at 3 V–3.6 V, enabling low-loss signal translation without level-shifter ICs. All I/O pins are 5.5-V tolerant.

Key Specifications

Pinout & Package

TSSOP-20 (RGY) package with 0.65 mm lead pitch, 6.50 mm × 4.40 mm body size, and exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9544ARGYR, PCA9545ARGYR adds essential interrupt handling for fault-aware systems; compared with TCA9548ARGYR, it offers lower R_ON and tighter timing margins for 4-channel deployments where pin count and thermal performance are critical.

Availability

PCA9545ARGYR is available at Aetrix Electronics and suitable for server backplane management, telecom switching equipment, and factory automation PLC modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for PCA9545ARGYR 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, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The PCA9545ARGYR belongs to TI's I²C switch and multiplexer product line, designed specifically to resolve slave address conflicts and enable scalable, modular I²C system architectures in space-constrained embedded platforms.

FAQ

What is the function of the RESET pin on the PCA9545ARGYR?

The RESET pin on the PCA9545ARGYR is an active-low asynchronous input that forces the device into a known state: it clears the control register to zero and deselects all four I²C channels. This recovers the device if any downstream bus becomes stuck low. A minimum 6 ns low pulse is required, and RESET must be pulled up externally to VCC. The PCA9545ARGYR also features a power-on reset that activates when VCC rises above 1.6 V.

How does the PCA9545ARGYR handle I²C slave address conflicts?

The PCA9545ARGYR resolves I²C slave address conflicts by isolating identical slave devices onto separate downstream channels (SC0/SD0–SC3/SD3). The master communicates with only one channel at a time via software-controlled bit writes to the 8-bit control register. Since each channel is electrically isolated, multiple slaves with identical addresses can coexist without collision - the PCA9545ARGYR ensures only the selected channel is visible to the master during each transaction.

Can the PCA9545ARGYR perform voltage-level translation between different I²C buses?

Yes, the PCA9545ARGYR supports voltage-level translation between I²C buses operating at different voltages (e.g., 1.8-V, 2.5-V, 3.3-V, and 5-V). Its pass-gate switch architecture uses VCC as the voltage reference, allowing each SCn/SDn pair to interface with slaves at a different voltage level - provided external pull-up resistors are connected to the appropriate rail. All I/O pins are 5.5-V tolerant, ensuring robustness across mixed-supply systems.

What is the maximum I²C clock frequency supported by the PCA9545ARGYR?

The PCA9545ARGYR supports I²C clock frequencies up to 400 kHz, fully compliant with Fast-Mode I²C specifications. Electrical characteristics confirm timing parameters (t_BUF, t_SCL, t_SCH) meet Fast-Mode requirements across the full 2.3 V–5.5 V supply range and –40°C to +85°C temperature range. Propagation delay is ≤1 ns (typ) with 15 pF load, preserving signal integrity at maximum speed.

How are the A0 and A1 pins used on the PCA9545ARGYR?

The A0 and A1 pins on the PCA9545ARGYR are hardware-configurable address inputs that set the two LSBs of the device's 7-bit I²C slave address. Each pin must be tied to either VCC or GND - floating connections are not allowed. This allows up to four PCA9545ARGYR devices to share the same I²C bus with unique addresses (0x70, 0x71, 0x72, or 0x73), enabling hierarchical bus expansion without address conflicts.