NXP Semiconductors PCA9671DK,118

Overview

PCA9671DK,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 1 MHz I²C-bus operation. It replaces the PCF8575 with higher drive strength, faster bus speed, and active-low RESET input instead of interrupt output-enabling LED PWM dimming and dense multi-device bus configurations in industrial control and server management.

For engineers reviewing the PCA9671DK,118 datasheet, PCA9671DK,118 pinout, PCA9671DK,118 application, or PCA9671DK,118 equivalent, key selection criteria include its 1 MHz Fm+ I²C compatibility, 25 mA per-pin sink capability for direct LED driving, 64 programmable slave addresses, and hardware RESET input-critical for robust I/O expansion in space-constrained embedded systems requiring high bus node density and reliable power-on initialization.

Technical Context

The PCA9671DK,118 implements a quasi-bidirectional I/O architecture where all 16 pins (P00–P07, P10–P17) default to HIGH at power-up and operate without direction-control signals. Its internal Power-On Reset (POR) and dedicated active-low RESET pin ensure deterministic initialization of I/O states and register contents independent of I²C-bus activity.

It supports full Fast-mode Plus compliance (1 MHz), with SDA capable of sinking 30 mA into 4000 pF buses-enabling longer traces or more parallel devices without bus buffers. Addressing uses three hardware pins (AD0–AD2) to select among 64 unique slave addresses, avoiding conflicts in complex multi-expander topologies.

Key Specifications

Pinout & Package

PCA9671DK,118 is supplied in HVQFN24 package (4 mm × 4 mm × 0.85 mm, no leads, 24-terminal thermal-enhanced quad flat). The exposed center pad must be soldered to PCB ground for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9673D,118, PCA9671DK,118 trades interrupt capability for deterministic hardware reset control-making it superior for systems requiring guaranteed I/O state recovery after power faults. Versus PCF8575CD,118, it delivers 2.5× bus speed, 10× SDA drive, and 4× sink capacity-enabling scalable, high-performance I/O expansion where legacy constraints do not apply.

Availability

PCA9671DK,118 is available at Aetrix Electronics and suitable for industrial control, server management, and medical equipment applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for PCA9671DK,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.

The PCA9671DK,118 belongs to NXP's Fast-mode Plus I²C I/O expander family, designed specifically to replace legacy expanders in high-density, high-speed embedded systems where bus scalability and direct LED driving are essential.

FAQ

What is the function of the RESET pin on the PCA9671DK,118?

The RESET pin on the PCA9671DK,118 is an active-low hardware input that asynchronously initializes all I/O registers and internal state machines to their power-on defaults. Holding RESET LOW for ≥tw(rst) forces the device into a known state regardless of I²C-bus activity-critical for system-level recovery after power faults or watchdog timeouts. Unlike the PCF8575, PCA9671DK,118 replaces the interrupt output with this dedicated RESET function.

Does the PCA9671DK,118 support 1 MHz I²C communication in all operating voltage ranges?

Yes, the PCA9671DK,118 supports full Fast-mode Plus (1 MHz) I²C operation across its entire specified supply range of 2.3 V to 5.5 V. This is confirmed in the official NXP datasheet Rev. 3 (2011), which specifies 1 MHz timing compliance at VDD = 2.3 V, 3.3 V, and 5.0 V-enabling consistent high-speed performance in mixed-voltage embedded systems without derating.

How many PCA9671DK,118 devices can share one I²C bus?

Up to 64 PCA9671DK,118 devices can coexist on a single I²C bus, as each unit supports 64 unique slave addresses set via AD0–AD2 pins. This assumes proper bus capacitance management (≤4000 pF) and adequate SDA/SCL pull-up strength-enabled by the device's 30 mA SDA sink capability, which reduces or eliminates the need for bus buffers even in dense configurations.

Can the PCA9671DK,118 directly drive LEDs, and what is the maximum current per pin?

Yes, the PCA9671DK,118 can directly drive LEDs with a guaranteed 25 mA sink current per I/O pin (P00–P07, P10–P17). Its total package sink capacity is 400 mA, allowing all 16 pins to operate simultaneously at 25 mA-sufficient for driving common-anode LED displays, status indicators, or small backlight arrays without external transistors or drivers.

What is the purpose of the device ID read feature in the PCA9671DK,118?

The device ID read feature in the PCA9671DK,118 provides a 24-bit read-only identifier containing manufacturer code (NXP), part identification (PCA9671), and die revision-accessible via reserved I²C address 0xF4 (1111 100x). This enables runtime verification, firmware version matching, and supply-chain traceability in automated test and field-upgrade scenarios, ensuring correct component integration in certified medical or industrial systems.