NXP Semiconductors PCA9542AD,112

Overview

PCA9542AD,112 from NXP Semiconductors is a 1-of-2 bidirectional I²C-bus translating multiplexer with integrated interrupt logic, operating from 2.3 V to 5.5 V supply, supporting up to 400 kHz clock frequency, featuring 5 V-tolerant I/O pins and low Ron (≤11 Ω typical) pass gates for voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses. It enables isolated I²C bus expansion in multi-sensor systems.

For engineers reviewing the PCA9542AD,112 datasheet, PCA9542AD,112 pinout, PCA9542AD,112 application, or PCA9542AD,112 equivalent, key selection considerations include channel-selectable I²C isolation, dual active-low interrupt inputs (INT0/INT1) with ANDed open-drain output (INT), hardware addressability via A0–A2, power-on reset defaulting to no-channel-selected state, and SO14 package compatibility with industrial temperature range (−40 °C to +85 °C).

Technical Context

The PCA9542AD,112 implements a single-pole double-throw (SPDT) analog switch architecture using low-Ron MOSFET pass gates controlled by an I²C-accessible 8-bit control register. Channel selection (channel 0, channel 1, or none) is determined solely by bits B2–B0 of the register, with activation deferred until STOP condition completion to prevent bus glitches.

Interrupt handling operates independently of channel selection: INT0 and INT1 monitor downstream devices on SC0/SD0 and SC1/SD1 respectively; their states are latched into read-only bits of the control register, and the open-drain INT output asserts LOW when either input is active. Voltage translation is enabled by VDD-referenced pass gate threshold control, allowing asymmetric bus voltages without external level shifters.

Key Specifications

Pinout & Package

PCA9542AD,112 is supplied in SO14 (SOT108-1) package: plastic small outline, 14-lead, 3.9 mm body width, surface-mount, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9542APWR, PCA9542AD,112 provides hardware-level interrupt aggregation essential for latency-sensitive fault detection; compared with PCA9544APW, it offers smaller SO14 footprint and lower component cost where only two downstream segments are needed.

Availability

PCA9542AD,112 is available at Aetrix Electronics and suitable for industrial automation, server management, and automotive body electronics requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.

Supply support for PCA9542AD,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 applications.

The PCA9542A product line delivers I²C-bus multiplexing with integrated voltage translation and interrupt logic, designed specifically for reliable expansion of I²C infrastructure in mixed-voltage embedded systems where bus isolation and fault containment are critical.

FAQ

What is the maximum I²C clock frequency supported by the PCA9542AD,112?

The PCA9542AD,112 supports I²C-bus operation up to 400 kHz, compliant with fast-mode I²C specifications. This maximum frequency is maintained across its full operating supply range (2.3 V to 5.5 V) and temperature range (−40 °C to +85 °C), with timing parameters including tLOW, tHIGH, and tSU;DAT verified per Table 10 of the datasheet. The PCA9542AD,112 does not support high-speed mode (3.4 MHz).

How does the PCA9542AD,112 perform voltage translation between different I²C bus domains?

The PCA9542AD,112 achieves voltage translation through VDD-referenced pass gate transistors: the maximum output voltage (Vo(sw)) passed to downstream buses is clamped by the VDD supply level. For example, setting VDD = 3.3 V limits Vo(sw) to ≤2.8 V, enabling safe interfacing of 3.3 V peripherals with a 5 V upstream bus. External pull-up resistors on each SCx/SDx pair set the final logic-high voltage per segment, and all I/O pins are 5 V tolerant regardless of VDD.

Does the PCA9542AD,112 require external pull-up resistors on its I²C lines?

Yes, the PCA9542AD,112 requires external pull-up resistors on all I²C lines: upstream SCL/SDA and both downstream SC0/SD0 and SC1/SD1 pairs. No internal pull-ups are provided. Resistor values must be selected based on bus capacitance and desired rise time - typical values range from 1 kΩ to 10 kΩ depending on voltage domain and speed. Pull-ups for INT0/INT1 (if used as inputs) and INT (open-drain output) also require external resistors.

What happens to the PCA9542AD,112 channels during power-up?

At power-up, the PCA9542AD,112 executes a hardware Power-On Reset (POR) that initializes the control register to 0x00 and deselects all channels (B2–B0 = 0). This ensures no downstream bus is electrically connected until explicitly enabled via I²C write, preventing bus contention or unintended device activation. POR triggers when VDD rises above VPOR (1.6–2.1 V) and completes before the I²C state machine becomes operational.

Can the PCA9542AD,112 interrupt inputs (INT0, INT1) be used for purposes other than interrupt signaling?

Yes, INT0 and INT1 can function as general-purpose digital inputs when interrupt functionality is not required. They are CMOS-compatible inputs with standard VIH/VIL thresholds (0.7VDD and 0.3VDD) and ±1 µA leakage. If unused, they must be tied to VDD via a pull-up resistor to avoid floating states - leaving them unconnected violates the absolute maximum rating for input voltage and risks erratic behavior.