NXP Semiconductors PCA9541PW/02,118

Overview

PCA9541PW/02,118 from NXP Semiconductors is a 2-to-1 bidirectional I²C-bus master selector IC with interrupt logic and reset, designed for high-reliability dual-master systems where continuous operation must be maintained during master failure or hot-swap maintenance. It supports 2.3 V to 5.5 V supply, 0–400 kHz clock frequency, and voltage-level translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses. It isolates failed masters while enabling controlled bus handover in telecom infrastructure and industrial control systems.

For engineers reviewing the PCA9541PW/02,118 datasheet, PCA9541PW/02,118 pinout, PCA9541PW/02,118 application, or PCA9541PW/02,118 equivalent, key selection criteria include bus recovery timing, interrupt masking flexibility, channel-select register behavior, and TSSOP16 package compatibility with 16-pin I²C routing constraints.

Technical Context

The PCA9541PW/02,118 implements a deterministic, non-arbitrated channel-switching mechanism triggered by STOP-command-locked writes to its dual CONTROL registers (one per master). Its internal bus sensor detects non-idle conditions on SCL_SLAVE/SDA_SLAVE and generates BUSOK interrupts when initialization is disabled.

Bus recovery is hardware-assisted: upon BUSINIT=1, it autonomously issues nine SCL_SLAVE clock pulses, releases SDA_SLAVE for NACK, then asserts STOP - resetting downstream slave state without external intervention. Interrupt propagation (INT0/INT1/INT_IN) is fully configurable via IE register bits including BUSLOSTMSK, BUSOKMSK, and INTINMSK.

Key Specifications

Pinout & Package

TSSOP16 package: 16-lead plastic thin shrink small outline, 0.65 mm pitch, 4.4 mm body width, exposed pad not present (unlike HVQFN16).

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/02,118 uniquely delivers hardware-enforced bus recovery, dual-master-specific interrupt masking, and deterministic ownership handover - critical for systems where I²C bus integrity must survive controller faults without software intervention.

Availability

PCA9541PW/02,118 is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLC redundancy, and medical diagnostic equipment requiring stable component supply across extended product lifecycles.

Supply support for PCA9541PW/02,118 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The PCA9541PW/02,118 belongs to NXP's I²C-bus infrastructure portfolio, engineered specifically for high-availability dual-master systems where bus continuity, fault isolation, and deterministic recovery are mandatory design requirements.

FAQ

What is the function of the BUSINIT bit in the PCA9541PW/02,118 CONTROL register?

The BUSINIT bit (bit 4) in the PCA9541PW/02,118 CONTROL register enables hardware-initiated bus recovery: when set to 1, the device automatically sends nine SCL_SLAVE clock pulses, releases SDA_SLAVE for NACK, and issues a STOP condition before switching channels. This ensures downstream slaves enter a known initialized state, eliminating residual bus contention. The PCA9541PW/02,118 asserts BUSINIT in its own CONTROL register and sets BUSINIT bit in the Interrupt Status Register upon completion.

How does the PCA9541PW/02,118 handle simultaneous channel requests from both masters?

The PCA9541PW/02,118 resolves simultaneous channel requests deterministically: the master whose CONTROL register write occurs immediately before the next STOP command wins the switch. There is no arbitration logic - the device updates the channel connection only on STOP, so timing of the STOP relative to the last CONTROL write determines outcome. This behavior is documented in Table 12 of the PCA9541PW/02,118 datasheet and ensures predictable, race-free handover.

Can the PCA9541PW/02,118 operate with different supply voltages on master and slave sides?

Yes - the PCA9541PW/02,118 uses VDD-limited pass gates to enable voltage-level translation. When VDD = 3.3 V, it safely interfaces 3.3 V masters with 5 V slaves; at VDD = 2.5 V, it connects 2.5 V masters to 3.3 V slaves. All I/O pins are 6.0 V tolerant, and no external level shifters are needed. This capability is intrinsic to the PCA9541PW/02,118 silicon design and confirmed in Section 2 of its product data sheet.

What is the purpose of the BUSOK interrupt in the PCA9541PW/02,118?

The BUSOK interrupt in the PCA9541PW/02,118 signals that a channel switch occurred while the downstream SCL_SLAVE/SDA_SLAVE bus was not idle - indicating potential incomplete transactions. It is generated only when BUSINIT = 0 and the internal bus sensor detects activity. The interrupt alerts the gaining master to perform external recovery (e.g., repeated START/STOP), and can be masked per master using BUSOKMSK in the IE register. This feature is unique to the PCA9541PW/02,118 among NXP's I²C switches.

Does the PCA9541PW/02,118 support hot insertion of controller cards?

Yes - the PCA9541PW/02,118 supports hot insertion due to its active LOW RESET input, no-glitch power-up behavior, and ability to isolate a removed master without disrupting communication between the remaining master and downstream slaves. Its internal Power-On Reset (POR) and RESET pin ensure consistent initialization regardless of insertion timing, making it suitable for modular telecom and server systems where controller cards are serviced without powering down.