NXP Semiconductors PCA9541PW/01,118

Overview

PCA9541PW/01,118 from NXP Semiconductors is a 2-to-1 I²C-bus master selector IC designed for fault-tolerant dual-master systems, featuring channel 0 pre-selected at power-up, active-low reset and interrupt logic, bus recovery initialization (9-clock pulse + NACK + STOP), and voltage-level translation across 1.8 V to 5 V domains. It enables hot-swappable controller redundancy in telecom base stations and industrial PLCs.

For engineers reviewing the PCA9541PW/01,118 datasheet, PCA9541PW/01,118 pinout, PCA9541PW/01,118 application, or PCA9541PW/01,118 equivalent, this device delivers deterministic bus arbitration-free channel switching, real-time bus traffic sensing, and configurable interrupt masking for high-availability I²C infrastructure design.

Technical Context

The PCA9541PW/01,118 implements a state-machine–driven switch control architecture with separate register banks per master (MST0/MST1), where channel selection occurs only on STOP command receipt. Its bus sensor detects non-idle conditions during switching and triggers BUSOK interrupts when external recovery is required.

It integrates dual active-low interrupt outputs (INT0/INT1), one active-low interrupt input (INT_IN), and an active-low reset input that synchronizes internal registers to default values. The device supports up to 16 addressable instances via four hardware-configurable address pins (A0–A3) and operates across 2.3 V to 5.5 V supply range with 6.0 V tolerant I/Os.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 4.4 mm body width, 16-pin surface-mount with exposed thermal pad on HVQFN variant (not applicable to PCA9541PW/01,118).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C master selector applications.

Compared with PCA9544APW,118 and TCA9544APWR, the PCA9541PW/01,118 uniquely provides master-selectable bus recovery, real-time traffic-aware switching, and dedicated interrupt signaling for ownership transitions-enabling true fault-tolerant I²C infrastructure rather than basic signal routing.

Availability

PCA9541PW/01,118 is available at Aetrix Electronics and suitable for telecom base station redundancy, industrial PLC dual-CPU arbitration, and medical imaging hot-swap modules requiring stable component supply across extended product lifecycles.

Supply support for PCA9541PW/01,118 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

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in interface and system-level ICs.

The PCA9541 product line was developed specifically for high-availability I²C systems requiring seamless dual-master failover, bus recovery, and voltage-domain interoperability in mission-critical infrastructure.

FAQ

What is the power-up behavior of the PCA9541PW/01,118?

The PCA9541PW/01,118 powers up with Channel 0 selected by default, ensuring the primary master gains immediate control of the downstream I²C bus. This behavior is fixed for the /01 variant and differs from the /03 version, which starts with no channel selected. Internal Power-On Reset (POR) configures all registers to their default states, including BUSON = 1 and MYBUS = 0 for MST0.

How does the bus recovery function work in the PCA9541PW/01,118?

When enabled via the BUSINIT bit in the Control Register, the PCA9541PW/01,118 executes a deterministic recovery sequence before switching channels: it sends nine SCL clock pulses, releases SDA_SLAVE (equivalent to a NACK), then issues a STOP condition on SCL_SLAVE/SDA_SLAVE. This forces downstream slaves into a known initialized state, preventing bus hang during master handover.

Can the PCA9541PW/01,118 translate between different I²C voltage domains?

Yes, the PCA9541PW/01,118 supports voltage-level translation between 1.8 V, 2.5 V, 3.3 V, and 5 V I²C domains. Its pass-gate switches use VDD as the reference voltage, limiting the maximum passed high voltage to VDD. This allows, for example, a 3.3 V master to safely communicate with 5 V slaves when VDD = 3.3 V, without external level shifters.

What interrupt signals does the PCA9541PW/01,118 generate and how are they used?

The PCA9541PW/01,118 provides three interrupt signals: INT0 and INT1 (active-low outputs indicating bus ownership for MST0/MST1), and INT_IN (active-low input propagating downstream events). INT0/INT1 assert when a master gains or loses control; BUSLOST, BUSOK, and BUSINIT bits in the Interrupt Status Register indicate specific transition causes and can be masked individually via the IE register.

Is the PCA9541PW/01,118 compatible with SMBus standards?

Yes, the PCA9541PW/01,118 is fully compatible with SMBus standards due to its I²C-bus interface logic, support for standard and fast-mode clock rates (up to 400 kHz), and implementation of SMBus timeout and alert response behaviors. Its 6.0 V tolerant I/Os and robust ESD protection further align with SMBus system-level reliability requirements.