NXP Semiconductors PCA9671BQ,118

Overview

PCA9671BQ,118 from NXP Semiconductors is a 16-bit remote I/O expander for Fast-mode Plus (Fm+) I²C-bus systems, featuring 1 MHz I²C operation, 25 mA per-pin sink capability, 400 mA total package sink current, and active-low RESET input. It replaces PCF8575 with higher bus speed, stronger drive, and expanded addressing-enabling LED PWM dimming and multi-device bus scalability in space-constrained industrial and server applications.

For engineers reviewing the PCA9671BQ,118 datasheet, PCA9671BQ,118 pinout, PCA9671BQ,118 application, or PCA9671BQ,118 equivalent, this device delivers deterministic quasi-bidirectional I/O control, programmable 64-slave addressing, readable device ID, and hardware/software reset-critical for reliable embedded I/O expansion where timing, thermal performance, and bus loading matter.

Technical Context

The PCA9671BQ,118 implements a latch-based quasi-bidirectional I/O architecture with internal Power-On Reset and external RESET pin control, initializing all 16 I/Os as inputs at power-up. Its Fm+ I²C interface supports 1 MHz clocking and 30 mA SDA sink drive to accommodate up to 4000 pF bus capacitance without buffers.

Each of the 16 I/O pins (P00–P07, P10–P17) operates with 25 mA sink capability and 5.5 V-tolerant I/Os across 2.3 V–5.5 V supply range. Addressing uses three pins (AD0–AD2) to select one of 64 slave addresses, while device identification is accessible via reserved I²C address 0xF4 (1111100x).

Key Specifications

Pinout & Package

DHVQFN24 package: 3.5 mm × 5.5 mm × 0.85 mm body, 24-terminal no-lead quad flat, thermally enhanced with exposed center pad connected to VSS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9673D,118, PCA9671BQ,118 trades interrupt capability for hardware reset-simplifying fault recovery in watchdog-managed systems. Against PCF8575CD,118, it delivers 2.5× faster I²C, 8.3× higher SDA drive, and 4× more address options-making it the upgrade path for modern industrial and server I/O expansion.

Availability

PCA9671BQ,118 is available at Aetrix Electronics and suitable for LED signage, server management, and industrial PLC applications requiring stable component supply, extended temperature operation, and high-current I/O expansion.

Supply support for PCA9671BQ,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 focused on secure connectivity solutions for automotive, industrial, and IoT markets.

The PCA9671BQ,118 belongs to NXP's Fast-mode Plus I²C I/O expander product line, designed specifically for high-density, high-reliability embedded systems needing scalable remote GPIO with robust reset and identification features.

FAQ

What is the primary function of the PCA9671BQ,118 in an embedded system?

The PCA9671BQ,118 serves as a 16-bit remote I/O expander that extends microcontroller GPIO capability via a 1 MHz Fast-mode Plus I²C interface. It provides latched, quasi-bidirectional I/O pins with 25 mA sink per pin and 400 mA total package sink capacity-enabling direct LED driving, sensor interfacing, and control signal generation without additional driver circuitry. Its active-low RESET input and software reset capability ensure deterministic initialization in mission-critical systems.

How does the PCA9671BQ,118 differ from the PCF8575 in practical design use?

The PCA9671BQ,118 upgrades the PCF8575 with 1 MHz I²C (vs. 400 kHz), 30 mA SDA sink drive (vs. 3 mA), 400 mA total sink (vs. 100 mA), and 64 slave addresses (vs. 8). Crucially, it replaces the PCF8575's interrupt output with a hardware RESET input-shifting emphasis from event notification to fail-safe recovery. This makes PCA9671BQ,118 ideal for systems where coordinated reset behavior outweighs interrupt latency requirements.

Can the PCA9671BQ,118 drive LEDs directly, and what are the current limits?

Yes, the PCA9671BQ,118 can drive LEDs directly using its 16 quasi-bidirectional I/O pins, each rated for 25 mA sink current. The total package sink capacity is 400 mA, allowing all 16 pins to operate at 25 mA simultaneously. For higher-current loads, two or more pins within the same octal (e.g., P00–P07) can be paralleled-up to 8 pins for 200 mA-provided they are controlled identically in firmware.

What package type is used by the PCA9671BQ,118, and why does it matter for thermal design?

The PCA9671BQ,118 uses the DHVQFN24 package: a 3.5 mm × 5.5 mm × 0.85 mm thermally enhanced quad flat no-lead package with an exposed center pad. This pad must be soldered to a PCB thermal pad connected via vias to internal ground planes. Proper thermal anchoring is essential-not just for heat dissipation under 400 mA load, but also for electrical stability, as the VSS pin and exposed pad are internally bonded and both must connect to system ground for correct operation.

How is device identification implemented in the PCA9671BQ,118, and what data does it return?

The PCA9671BQ,118 implements a 24-bit read-only Device ID accessible via I²C address 0xF4 (1111100x). It returns three bytes: 8 bits of manufacturer ID (NXP Semiconductors), 13 bits of part identification (including category and feature codes for "16-bit quasi-output I/O expander"), and 3 bits of die revision. This enables firmware to validate hardware identity during boot, support field diagnostics, and enforce compatibility checks before configuring I/O registers.