NXP Semiconductors PCA9542APW/DG,118

Overview

PCA9542APW/DG,118 from NXP Semiconductors is a 1-of-2 bidirectional I²C-bus translating multiplexer with integrated interrupt logic, designed to isolate and route I²C traffic between one upstream master and two downstream slave channels. It supports voltage translation across 1.8 V, 2.5 V, 3.3 V, and 5 V domains, features active-low INT0/INT1 inputs and a wired-AND INT output, and operates from 2.3 V to 5.5 V supply. It enables scalable I²C expansion in server management, industrial PLCs, and multi-sensor embedded systems.

For engineers reviewing the PCA9542APW/DG,118 datasheet, PCA9542APW/DG,118 pinout, PCA9542APW/DG,118 application, or PCA9542APW/DG,118 equivalent, this device delivers deterministic channel selection via I²C-controlled register, robust 400 kHz Fast-mode operation, 5 V-tolerant I/O, low standby current (≤1 µA), and hot-insertion support - critical for fault-tolerant system monitoring and modular peripheral interfacing.

Technical Context

The PCA9542APW/DG,118 implements a dual-channel pass-gate architecture with VDD-referenced voltage clamping, enabling bidirectional level translation without external level shifters. Its control register (8-bit, read/write) uses B2–B0 bits to select Channel 0 (0x04) or Channel 1 (0x05), while INT0/INT1 status bits (bit 5/4) reflect real-time interrupt conditions independent of channel enable state.

Interrupt handling is asynchronous: INT0 and INT1 are sampled continuously and latched into the control register on read, allowing the master to identify interrupt source before reconfiguring channel routing. The internal power-on reset initializes all registers to zero (no channel selected) and ensures glitch-free startup across −40 °C to +85 °C ambient.

Key Specifications

Pinout & Package

TSSOP14 package (SOT402-1): 14-lead plastic thin shrink small outline, 4.4 mm body width, 0.65 mm lead pitch, surface-mount compatible.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9542APWR and PCA9544APW,118, the PCA9542APW/DG,118 offers the lowest standby current (≤1 µA), guaranteed 1.8 V translation capability, and power-on deselection - making it optimal for ultra-low-power, mixed-voltage, and safety-critical channel isolation where deterministic initialization is mandatory.

Availability

PCA9542APW/DG,118 is available at Aetrix Electronics and suitable for server BMC architectures, industrial PLC backplanes, and battery-powered sensor hubs requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9542APW/DG,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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in I²C infrastructure and system-level power management.

The PCA9542A product line was designed to solve I²C bus congestion and voltage-domain bridging in resource-constrained embedded systems, delivering deterministic multiplexing, interrupt consolidation, and robust mixed-signal interoperability.

FAQ

What is the default channel state of PCA9542APW/DG,118 after power-on reset?

Upon power-on reset, the PCA9542APW/DG,118 initializes its control register to 0x00, deselecting both Channel 0 and Channel 1. This ensures no downstream I²C segment is electrically connected until explicitly enabled via I²C write - preventing bus contention and undefined states during system boot. The PCA9542APW/DG,118 remains in this safe, high-impedance state until the master writes a valid channel-select command (0x04 or 0x05) followed by a STOP condition.

Can PCA9542APW/DG,118 translate between 1.8 V and 5 V I²C buses simultaneously?

Yes, the PCA9542APW/DG,118 supports simultaneous 1.8 V ↔ 5 V translation using its VDD-referenced pass-gate architecture. When VDD is set to 2.3 V–2.7 V, Vo(sw) is clamped to ≤2.0 V, enabling safe interfacing of 1.8 V downstream devices with a 5 V upstream master. External pull-up resistors on each SCx/SDx pair must match their respective bus voltages, and all I/O pins remain 5 V tolerant regardless of VDD setting.

How does the interrupt logic in PCA9542APW/DG,118 operate when multiple devices assert INT0?

The PCA9542APW/DG,118 treats INT0 and INT1 as asynchronous, level-sensitive inputs - it does not decode or prioritize individual devices on a channel. If multiple peripherals on Channel 0 drive INT0 LOW, the PCA9542APW/DG,118 latches that state in bit 4 of the control register. The master must then select Channel 0 and poll each attached device individually to clear the interrupt condition, as the PCA9542APW/DG,118 provides no built-in arbitration or masking.

What is the maximum capacitive load supported on each I²C channel of PCA9542APW/DG,118?

The PCA9542APW/DG,118 supports up to 400 pF total capacitance per bus line (SDx or SCx), consistent with Fast-mode I²C specifications. This allows reliable operation with typical trace lengths, connectors, and up to ~10–15 standard I²C slave devices per channel. Exceeding 400 pF may violate tR/tF timing limits (≤300 ns fall time, ≤1000 ns rise time), requiring reduced clock frequency or active bus buffering.

Is PCA9542APW/DG,118 compatible with SMBus protocols?

Yes, the PCA9542APW/DG,118 is fully SMBus-compatible: it adheres to SMBus 2.0 electrical specifications (including timeout, alert response, and packet error checking), supports the same 100 kHz/400 kHz clock rates, and implements SMBus Alert protocol via its INT output. Its 5 V-tolerant I/O, low standby current, and interrupt aggregation make it suitable for SMBus-based system management in servers and telecom equipment.