Nexperia USA Inc. PCA9555PWJ

Overview

PCA9555PWJ from Nexperia is a low-voltage 16-bit I²C-bus GPIO expander with interrupt output, weak internal pull-up resistors, and 2.3 V to 5.5 V operation. It provides two 8-bit bidirectional I/O ports (P0 and P1), configurable input/output direction per pin via configuration registers, and an open-drain active-low INT signal triggered by input state changes - used in ACPI power switches, LED/fan control, and sensor interface subsystems.

For engineers reviewing the PCA9555PWJ datasheet, PCA9555PWJ pinout, PCA9555PWJ application, or PCA9555PWJ equivalent, key selection criteria include its 400 kHz Fast-mode I²C support, 25 mA sink capability per I/O, -40 °C to +85 °C industrial temperature range, TSSOP24 package, and hardware-configurable slave address (A0–A2) enabling up to eight devices on one bus.

Technical Context

The PCA9555PWJ implements a dual-port register architecture with four 8-bit register pairs: Input (00h/01h), Output (02h/03h), Polarity Inversion (04h/05h), and Configuration (06h/07h). All I/Os power up as high-impedance inputs with internal ~100 kΩ pull-ups, and the INT output asserts on any edge transition of configured input pins.

Its I²C interface supports standard and Fast-mode (up to 400 kHz), includes Schmitt-trigger inputs on SCL/SDA for noise immunity, and features internal power-on reset that initializes all registers to default states - including output port bits set to '1' and configuration bits set to '1' (input mode).

Key Specifications

Pinout & Package

TSSOP24 (SOT355-1) package: 24-pin plastic thin shrink small outline, 4.4 mm body width, surface-mount compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar GPIO expansion applications.

Compared with PCA9554PW, the PCA9555PWJ doubles I/O capacity without increasing software complexity; versus TPS65987D, it offers simpler integration, lower cost, and broader compatibility in non-USB-C systems requiring pure parallel I/O extension.

Availability

PCA9555PWJ is available at Aetrix Electronics and suitable for industrial control panels, embedded computing platforms, and smart sensor hubs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for PCA9555PWJ 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

Nexperia is a global semiconductor expert focused on high-volume, high-reliability logic, analog, and MOSFET solutions for automotive, industrial, and consumer markets.

The PCA9555 belongs to Nexperia's I²C GPIO expander product line, designed specifically to simplify system-level I/O resource scaling while maintaining low power, robust ESD performance, and seamless integration with legacy microcontrollers.

FAQ

What is the function of the INT pin, and how is it used in system design?

The INT pin is an open-drain active-low interrupt output that asserts whenever any GPIO configured as an input changes state. It must be pulled up to VCC externally. In system design, this pin connects to a microcontroller's external interrupt pin, allowing event-driven response instead of polling - reducing CPU load and improving real-time responsiveness for buttons, sensors, or status flags.

Can the PCA9555PWJ drive LEDs directly, and what are the current limitations?

Yes - each I/O pin can sink up to 25 mA continuously, sufficient to drive standard indicator LEDs directly. When configured as an output, the pin pulls low to illuminate an LED connected between VCC and the I/O. However, total device supply current must remain within 160 mA, and simultaneous full-load operation of all 16 pins is not recommended due to thermal limits and voltage drop.

How does the PCA9555PWJ handle power-on initialization, and why is it important?

It includes an internal power-on reset (POR) circuit that holds the device in reset until VCC reaches ≥1.25 V, then initializes all registers to defined defaults: all I/Os as inputs, output registers set to 0xFF, and configuration registers set to 0xFF. This ensures predictable, glitch-free startup - critical for systems where uncontrolled I/O states could cause latch-up, false triggers, or unsafe actuator activation.

Is the PCA9555PWJ compatible with 5 V I²C buses when operating from a 3.3 V supply?

Yes - its SDA and SCL inputs are 5 V tolerant, and all 16 I/O pins accept input voltages up to 6 V regardless of VCC level. When powered from 3.3 V, it safely interfaces with 5 V peripherals and I²C masters, provided external pull-ups on SDA/SCL are tied to the master's VCC (5 V), and level-shifting is not required for communication integrity.