NXP Semiconductors PCAL9554CPWJ

Overview

PCAL9554CPWJ from NXP Semiconductors is an 8-bit I²C-bus/SMBus GPIO expander with Agile I/O features, interrupt output, and programmable pull-up/pull-down resistors. It operates from 1.65 V to 5.5 V, supports 400 kHz Fast-mode I²C, delivers 25 mA sink per I/O, and powers up with all pins configured as inputs - enabling reliable system bring-up in ACPI power switches, LED/fan control, and sensor interface applications.

For engineers reviewing the PCAL9554CPWJ datasheet, PCAL9554CPWJ pinout, PCAL9554CPWJ application, or PCAL9554CPWJ equivalent, this device offers verified interrupt masking, latchable inputs, per-pin drive strength control, and hardware address selection via A0–A2 - critical for multi-device I²C bus design, low-power embedded systems, and industrial control interfaces requiring deterministic interrupt handling and flexible I/O configuration.

Technical Context

The PCAL9554CPWJ implements a dual-register architecture: standard PCA9554A-compatible registers (Input/Output/Configuration/Polarity Inversion) plus Agile I/O extended registers (Output Drive Strength, Input Latch, Pull-up/Pull-down Enable/Selection, Interrupt Mask/Status, Output Port Configuration). Its interrupt logic responds to input state changes only when unmasked and latched, with INT de-assertion tied to Input Port register reads - ensuring no spurious interrupts at power-up due to default mask-all behavior.

Each of the eight bidirectional I/Os supports independent configuration: push-pull or open-drain output stage selection (via 4Fh), four-level programmable drive strength (0.25×–1×), 100 kΩ selectable pull-up/down (44h), and latch enable (42h). All I/Os are 5 V tolerant and feature Schmitt-trigger inputs with 0.10 × VDD hysteresis, enabling robust operation with slow or noisy signals on SCL/SDA and port lines.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 4.4 mm body width, 0.65 mm pitch; thermally enhanced for stable operation in compact industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9554APW, PCAL9554CPWJ adds deterministic interrupt handling and I/O flexibility; compared with PCAL9554BPWJ, it provides distinct I²C addressing to avoid conflicts in multi-device systems - making it optimal for new designs requiring both feature richness and bus scalability.

Availability

PCAL9554CPWJ is available at Aetrix Electronics and suitable for industrial control panels, embedded computing platforms, and IoT gateway designs requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for PCAL9554CPWJ 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 ecosystem components and embedded interface IP.

The PCAL9554CPWJ belongs to NXP's Agile I/O GPIO expander family, designed specifically to extend microcontroller I/O capability in space-constrained, low-power, and interrupt-sensitive embedded systems - balancing flexibility, reliability, and ease of integration.

FAQ

What is the I²C slave address of PCAL9554CPWJ?

The PCAL9554CPWJ uses a fixed 7-bit I²C slave address of 0x70 (0111xxx), where the three least-significant bits are set by hardware pins A2, A1, and A0. This base address distinguishes it from the PCAL9554BPWJ (0x40) and allows up to eight identical PCAL9554CPWJ devices on a single I²C bus without address conflict. The full address byte includes R/W bit (0 for write, 1 for read).

How does the interrupt masking behavior work on PCAL9554CPWJ at power-up?

At power-on reset, all bits in the Interrupt Mask register (45h) default to logic 1, disabling interrupts for all eight I/Os. This prevents spurious interrupts during system initialization. To enable interrupts on specific pins, firmware must write '0' to the corresponding mask bits. The PCAL9554CPWJ remains in this safe, masked state until explicitly reconfigured - a key reliability feature for robust embedded boot sequences.

Can PCAL9554CPWJ drive LEDs directly, and what current capability does it provide?

Yes, PCAL9554CPWJ can drive LEDs directly via its I/O pins, each capable of sinking up to 25 mA. This eliminates the need for external transistor drivers in low-to-moderate brightness indicator applications. Drive strength is programmable (four levels) to optimize current for different LED forward voltages and desired luminance, while maintaining compatibility with 1.65–5.5 V supply rails.

What is the purpose of the Input Latch register (42h) in PCAL9554CPWJ?

When enabled via the Input Latch register (42h), a state change on a configured input pin is captured and held in the Input Port register until explicitly read - preventing loss of transient events during slow host polling or I²C bus contention. This ensures no input transition is missed, unlike non-latched mode where returning to the original state before reading clears the interrupt.

Does PCAL9554CPWJ support 5 V tolerant I/Os, and how does that benefit system design?

Yes, all eight I/O pins (P0–P7) of PCAL9554CPWJ are 5 V tolerant, meaning they can safely accept input signals up to 5.5 V regardless of VDD level (1.65–5.5 V). This allows direct interfacing with legacy 5 V sensors, switches, or logic without level-shifting circuitry - simplifying BOM, reducing PCB complexity, and improving signal integrity in mixed-voltage industrial and automotive subsystems.