NXP Semiconductors PCA9542APW,118

Overview

PCA9542APW,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 controllers and multi-sensor embedded systems.

For engineers reviewing the PCA9542APW,118 datasheet, PCA9542APW,118 pinout, PCA9542APW,118 application, or PCA9542APW,118 equivalent, this device delivers deterministic channel selection via I²C-controlled register writes, glitch-free power-up behavior, hot-insertion support, and 400 kHz Fast-mode I²C compatibility - critical for fault-tolerant system monitoring and mixed-voltage sensor hub designs.

Technical Context

The PCA9542APW,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) uses B2–B0 bits to select Channel 0 (0x04), Channel 1 (0x05), or deselect both (0x00), with INT0/INT1 status bits readable at bits 5/4.

Interrupt handling is asynchronous: INT0 and INT1 are sampled continuously and reflected in the control register regardless of channel selection state; the open-drain INT output asserts low when either input is low. Power-on reset initializes all registers to zero and holds the I²C state machine inactive until VDD exceeds VPOR (1.6–2.1 V).

Key Specifications

Pinout & Package

TSSOP14 package (SOT402-1): plastic thin shrink small outline, 14-lead, body width 4.4 mm, lead pitch 0.65 mm, moisture sensitivity level (MSL) 1 - suitable for standard reflow soldering per J-STD-020D.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9544APW,118, the PCA9542APW,118 reduces component count and layout complexity for dual-channel systems; versus TCA9542APWR, it offers guaranteed NXP manufacturing traceability and identical register-level behavior per Rev. 5.1 datasheet - critical for automotive and industrial certifications.

Availability

PCA9542APW,118 is available at Aetrix Electronics and suitable for server baseboard management, industrial sensor hubs, and telecom line card monitoring requiring stable component supply, long-lifecycle support, and guaranteed authentic NXP sourcing.

Supply support for PCA9542APW,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 interface, power, and security ICs.

The PCA9542A product line delivers scalable I²C-bus multiplexing with integrated voltage translation and interrupt aggregation, targeting space-constrained, mixed-voltage embedded systems requiring reliable bus isolation and fault diagnostics.

FAQ

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

Upon power application, the PCA9542APW,118 enters a reset state until VDD exceeds VPOR (1.6–2.1 V), then initializes all registers to zero - deselecting both channels, clearing interrupt flags, and holding the I²C state machine inactive. This ensures no unintended bus activity occurs during startup, and the PCA9542APW,118 remains in a known-safe state until first configured via I²C.

How does the PCA9542APW,118 handle voltage translation between different I²C bus domains?

The PCA9542APW,118 uses VDD-referenced pass-gate transistors to clamp the maximum voltage passed between upstream and downstream buses. For example, with VDD = 3.3 V, Vo(sw) is limited to ~1.9–2.8 V, allowing safe interfacing of a 5 V master with 3.3 V or 1.8 V slaves. External pull-up resistors on each SCx/SDx pair set final bus voltage levels, and all I/O pins are 5 V tolerant - making the PCA9542APW,118 a self-contained translation solution.

Can the PCA9542APW,118 interrupt inputs be used for general-purpose digital inputs?

Yes - INT0 and INT1 can serve as general-purpose active-low digital inputs when interrupt functionality is unused. However, they must not be left floating: unused inputs require connection to VDD via a pull-up resistor to ensure defined logic states and prevent noise-induced false triggers. The PCA9542APW,118 does not include internal pull-ups on these pins, so external biasing is mandatory for reliable operation.

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

The PCA9542APW,118 supports up to 400 pF total capacitance per bus line (Cb), consistent with I²C Fast-mode specifications. This allows reliable operation with longer traces, multiple slave devices, or added filtering components without violating rise/fall time limits. At 400 kHz, rise time is specified as ≤300 ns with 1 kΩ pull-up and 50 pF load - confirming robust timing margin even under worst-case capacitive loading conditions for the PCA9542APW,118.

Does the PCA9542APW,118 support hot insertion of downstream I²C devices?

Yes - the PCA9542APW,118 supports hot insertion of downstream devices on SCx/SDx channels. Its architecture isolates unselected channels electrically, preventing bus contention or voltage back-feeding during plug-in events. Combined with glitch-free power-up and asynchronous interrupt sampling, this ensures upstream I²C traffic remains uninterrupted during live peripheral replacement - a key requirement validated in server and telecom applications using the PCA9542APW,118.