NXP Semiconductors PCA9541APW/01,112

Overview

PCA9541APW/01,112 from NXP Semiconductors is a 2-to-1 I²C-bus master selector IC designed for high-reliability dual-master systems requiring uninterrupted operation during master failure or hot-swap maintenance. It features channel 0 default selection 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 failover control of shared slave devices in telecom base stations.

For engineers reviewing the PCA9541APW/01,112 datasheet, PCA9541APW/01,112 pinout, PCA9541APW/01,112 application, or PCA9541APW/01,112 equivalent, key selection criteria include its TSSOP16 package, 2.3–5.5 V supply range, 400 kHz max clock frequency, 6 V-tolerant I/Os, and dual-interrupt signaling for bus ownership handoff and recovery status.

Technical Context

The PCA9541APW/01,112 implements a deterministic, non-arbitrated bus switching architecture where either upstream master gains exclusive downstream access via I²C register writes to its dedicated CONTROL register (Reg#01), followed by a STOP condition. Its internal bus sensor detects non-idle conditions during channel switch and triggers BUSOK interrupts when external recovery is required.

It integrates independent interrupt enable (IE) and status (ISTAT) registers per master, supports hardware address selection via A0–A3 pins (up to 16 devices on one bus), and performs automatic bus initialization-sending nine SCL pulses, releasing SDA, then issuing STOP-to reset downstream slaves before channel handover.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 16-pin plastic thin shrink small outline, 4.4 mm body width, lead pitch 0.65 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9541AD/01,112 and PCA9541ABS/01,118, the PCA9541APW/01,112 offers the best balance of compactness, manufacturability, and thermal performance for mid-density industrial and telecom boards - its TSSOP16 footprint supports automated assembly while delivering lower profile than SO16 and simpler layout than HVQFN.

Availability

PCA9541APW/01,112 is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and server management systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for PCA9541APW/01,112 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The PCA9541A product line was developed specifically for high-availability I²C systems requiring dual-master redundancy, bus recovery, and voltage-domain bridging - targeting telecom, medical, and industrial control applications where bus continuity is mission-critical.

FAQ

What is the default channel selection behavior of the PCA9541APW/01,112 at power-up?

The PCA9541APW/01,112 powers up with Channel 0 selected by default, as defined by its /01 variant designation. This ensures the primary master gains immediate control of the downstream I²C bus upon system start-up, providing deterministic initialization in redundant controller architectures without requiring initial register writes.

How does the PCA9541APW/01,112 handle bus recovery when switching between masters?

The PCA9541APW/01,112 supports two recovery modes: if BUSINIT is set, it autonomously sends nine SCL pulses, releases SDA (NACK), then issues STOP before connecting the new master; if BUSINIT is clear and the bus is non-idle, it asserts BUSOK interrupt to signal that external recovery is required - both mechanisms prevent slave lockup during handover.

Can the PCA9541APW/01,112 translate voltage levels between different I²C domains?

Yes, the PCA9541APW/01,112 uses VDD-limited pass gates to enable voltage-level translation: setting VDD to 3.3 V allows 3.3 V masters to safely communicate with 5 V slaves, while VDD = 1.8 V supports interfacing with 1.8 V peripherals - no external level shifters are needed, and all I/O pins are 6 V tolerant.

What is the function of the INT_IN pin on the PCA9541APW/01,112?

The INT_IN pin on the PCA9541APW/01,112 is an active-low interrupt input that collects asynchronous interrupt signals from downstream I²C peripherals (e.g., sensor alerts or fault flags) and propagates them to both upstream masters via INT0 and INT1 when enabled - enabling centralized event handling across redundant controllers.

Does the PCA9541APW/01,112 require external pull-up resistors on all I²C lines?

Yes, the PCA9541APW/01,112 requires external pull-up resistors on all I²C lines - including SCL_MST0, SDA_MST0, SCL_MST1, SDA_MST1, SCL_SLAVE, SDA_SLAVE, INT0, INT1, and INT_IN - because it contains no internal pull-ups; resistor values must be selected based on bus capacitance and speed requirements per I²C specification.