NXP Semiconductors PCA9673BQ,118

Overview

PCA9673BQ,118 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, 400 mA total package sink capacity, and active-low open-drain interrupt output. It operates from 2.3 V to 5.5 V, supports 1 MHz I²C-bus communication, and features hardware RESET and software reset capability-enabling LED dimming control and high-density bus expansion in space-constrained industrial interfaces.

For engineers reviewing the PCA9673BQ,118 datasheet, PCA9673BQ,118 pinout, PCA9673BQ,118 application, or PCA9673BQ,118 equivalent, this device delivers verified Fm+ timing compliance, programmable 16-slave addressing via AD0/AD1, readable device ID (manufacturer/part/revision), and latch-based output retention-critical for embedded I/O consolidation where bus speed, interrupt-driven responsiveness, and thermal-efficient QFN packaging are required.

Technical Context

The PCA9673BQ,118 implements a dual-octet quasi-bidirectional I/O architecture with latched outputs, where Port 0 (P00–P07) and Port 1 (P10–P17) operate independently and default to HIGH at power-up. Its I²C interface complies with Fast-mode Plus (1 MHz) and Standard-mode (100 kHz), with SDA capable of sinking 30 mA into 4000 pF buses-enabling direct connection to long traces or multiple downstream devices without bus buffers.

Internal Power-On Reset (POR), dedicated active-low RESET pin, and software-initiated reset (via General Call 00h + 06h) ensure deterministic initialization. The active-low open-drain INT output asserts on any port edge transition and clears automatically upon read/write access to the triggering port-eliminating polling overhead in microcontroller-hosted systems.

Key Specifications

Pinout & Package

DHVQFN24 package (3.5 × 5.5 × 0.85 mm, no leads, exposed thermal pad); requires soldering of exposed pad to PCB thermal plane for optimal thermal performance and electrical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9672BQ,118, the PCA9673BQ,118 doubles I/O count and retains identical thermal packaging and Fm+ timing; versus PCF8575CPW,118, it upgrades bus speed, address flexibility, sink capacity, and adds hardware reset-making it suitable for next-generation embedded control where scalability and responsiveness are critical.

Availability

PCA9673BQ,118 is available at Aetrix Electronics and suitable for industrial PLCs, medical equipment panels, and LED signage systems requiring stable component supply, extended temperature operation (-40°C to +85°C), and verified I²C-bus interoperability.

Supply support for PCA9673BQ,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 I²C ecosystem components and embedded interface IP.

The PCA9673BQ,118 belongs to NXP's Fast-mode Plus I²C I/O expander product line, designed specifically for high-density, interrupt-driven remote I/O consolidation in thermally demanding and electrically noisy environments.

FAQ

What is the primary function of the PCA9673BQ,118 in an embedded system?

The PCA9673BQ,118 serves as a 16-bit remote I/O expander that extends microcontroller GPIO capability over an I²C-bus. It provides quasi-bidirectional ports with latched outputs, 25 mA sink per pin, and an active-low interrupt output-enabling efficient, low-pin-count expansion for LED control, button sensing, and peripheral interfacing without consuming native MCU I/O resources. Its design centers on reducing system complexity while maintaining deterministic timing and robustness.

Does the PCA9673BQ,118 support 1 MHz I²C communication in all operating conditions?

Yes, the PCA9673BQ,118 fully complies with I²C Fast-mode Plus (Fm+) specifications up to 1 MHz across its entire rated supply range (2.3 V to 5.5 V) and temperature range (-40°C to +85°C). This is validated by its 30 mA SDA sink capability into 4000 pF buses-ensuring reliable high-speed signaling even with long traces or multiple capacitive loads-unlike standard Fast-mode (400 kHz) expanders such as the PCF8575.

How does the RESET pin on the PCA9673BQ,118 differ from the PCF8575's A2 pin?

The PCA9673BQ,118 replaces the PCF8575's A2 address pin with an active-low hardware RESET input (Pin 24). This allows synchronous system-level recovery independent of I²C bus state-critical when the bus is stalled or corrupted. Unlike address configuration, RESET forces all I/Os and registers to power-up defaults immediately, providing deterministic fault recovery not possible with software-only reset sequences.

Can the PCA9673BQ,118 drive LEDs directly without external current-limiting resistors?

No-the PCA9673BQ,118 requires external series resistors for LED driving. While it provides 25 mA sink capability per pin and 400 mA total package capacity, the internal output structure lacks built-in current regulation. External resistors must be selected based on forward voltage, desired LED current, and VDD to ensure safe operation within absolute maximum ratings and thermal limits of the DHVQFN24 package.

What is the purpose of the Device ID register in the PCA9673BQ,118?

The PCA9673BQ,118 includes a read-only 24-bit Device ID register containing 8 bits of manufacturer code (NXP), 13 bits of part identification (PCA9673), and 3 bits of die revision. Accessed via reserved I²C address 0xF4 (1111 100b), it enables runtime firmware validation, automated BOM verification, and counterfeit detection-ensuring the correct silicon revision is deployed in safety-critical or regulated applications like medical or industrial control systems.