NXP Semiconductors PCA9673PW,112

Overview

PCA9673PW,112 from NXP Semiconductors is a 16-bit remote I/O expander for Fast-mode Plus (Fm+) I²C-bus systems, providing quasi-bidirectional I/O ports with 25 mA sink per pin, 1 MHz I²C interface, and active-low open-drain interrupt output. It replaces the PCF8575 with higher bus speed, greater drive capability (30 mA SDA sink), 400 mA total package sink, and 16 programmable slave addresses - enabling LED dimming control in signage and industrial HMI panels.

For engineers reviewing the PCA9673PW,112 datasheet, PCA9673PW,112 pinout, PCA9673PW,112 application, or PCA9673PW,112 equivalent, key selection considerations include its TSSOP24 package, RESET input (replacing PCF8575's A2), interrupt-driven I/O change detection, 2.3–5.5 V operation with 5.5 V-tolerant I/Os, and compatibility with Fm+ I²C-bus timing requirements.

Technical Context

The PCA9673PW,112 implements a latch-based quasi-bidirectional I/O architecture where all 16 pins (P00–P07, P10–P17) default to high-impedance inputs at power-up and support independent read/write access via two-byte I²C transfers. Its internal Power-On Reset (POR), hardware RESET pin, and software reset sequence (General Call + 06h) ensure deterministic initialization.

It integrates dedicated interrupt logic that asserts INT on any rising/falling edge of input port transitions, with automatic deassertion upon port read/write - eliminating polling overhead. The device supports 16 unique slave addresses via AD0/AD1 pins and includes a 24-bit read-only Device ID register (manufacturer, part ID, revision) accessible via reserved I²C address 0xF4.

Key Specifications

Pinout & Package

TSSOP24 package (SOT355-1): plastic thin shrink small outline, 24 leads, 4.4 mm body width, lead pitch 0.65 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar remote I/O expander applications.

Compared with PCF8575T/3,118 and PCA9539PW,118, the PCA9673PW,112 delivers 2.5× higher I²C bandwidth, 4× greater total sink current, and integrated hardware RESET - making it the only option among the three capable of driving full-brightness LED arrays while maintaining real-time bus responsiveness in dense multi-device systems.

Availability

PCA9673PW,112 is available at Aetrix Electronics and suitable for LED signage, industrial PLCs, medical HMI panels, and server rack management requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for PCA9673PW,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 leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in I²C ecosystem components and interface IP.

The PCA9673PW,112 belongs to NXP's Fast-mode Plus I²C remote I/O family, designed specifically to upgrade legacy PCF857x-based systems with higher speed, stronger drive, and enhanced system control features like hardware RESET and robust interrupt handling.

FAQ

What is the primary function of the PCA9673PW,112 in an embedded system?

The PCA9673PW,112 serves as a 16-bit remote I/O expander that extends microcontroller GPIO capability via a 1 MHz Fast-mode Plus I²C-bus interface. It provides quasi-bidirectional ports with 25 mA sink per pin, active-low interrupt output, and hardware RESET - enabling scalable, low-overhead control of LEDs, switches, and sensors without consuming native MCU pins. Its design directly targets upgrades from PCF8575-based systems.

How does the RESET pin on the PCA9673PW,112 differ from the PCF8575's A2 pin?

The PCA9673PW,112 replaces the PCF8575's A2 address pin with an active-low hardware RESET input (Pin 3), allowing synchronous system-level reset independent of I²C bus activity. This eliminates address conflict risks during initialization and provides deterministic recovery - unlike the PCF8575, which relies solely on Power-On Reset and lacks a dedicated reset pin. The PCA9673PW,112 retains AD0 and AD1 for 16-address configuration.

Can the PCA9673PW,112 drive LEDs directly, and what are the current limits?

Yes, the PCA9673PW,112 can drive LEDs directly: each of its 16 I/O pins sinks up to 25 mA, and the total package sink capacity is 400 mA. This allows simultaneous operation of all 16 pins at full rated current - sufficient for driving standard indicator or signage LEDs without external drivers. Exceeding 25 mA per pin or 400 mA total risks thermal shutdown or permanent damage to the PCA9673PW,112.

What is the role of the INT pin, and how is it triggered?

The INT pin on the PCA9673PW,112 is an active-low open-drain interrupt output that asserts when any rising or falling edge occurs on configured input ports (P00–P07, P10–P17). It deasserts automatically after a port read or write operation - eliminating the need for explicit clear commands. This enables event-driven firmware design, reducing MCU polling overhead in applications like industrial sensor monitoring or HMI button detection using the PCA9673PW,112.

Does the PCA9673PW,112 support software reset, and how is it executed?

Yes, the PCA9673PW,112 supports software reset via the I²C General Call address (00h) followed by data byte 06h. Upon receiving this exact two-byte sequence (START → 00h → ACK → 06h → ACK → STOP), the device resets all registers to power-up defaults. This feature enables remote recovery without hardware intervention and is fully documented in the PCA9673PW,112 datasheet Section 7.2.1.