NXP Semiconductors PCA9671PW,112

Overview

PCA9671PW,112 from NXP Semiconductors is a 16-bit remote I/O expander for Fast-mode Plus (Fm+) I²C-bus systems, providing quasi-bidirectional GPIO with 25 mA sink per pin, 400 mA total package sink capacity, and 1 MHz I²C interface - enabling direct LED PWM dimming and high-density bus deployment in space-constrained industrial control and server applications.

For engineers reviewing the PCA9671PW,112 datasheet, PCA9671PW,112 pinout, PCA9671PW,112 application, or PCA9671PW,112 equivalent, key selection factors include its active-low RESET input (replacing PCF8575's interrupt), 64 programmable slave addresses, 2.3–5.5 V operation with 5.5 V-tolerant I/Os, and TSSOP24 packaging optimized for thermal and board-area efficiency.

Technical Context

The PCA9671PW,112 implements a latch-based quasi-bidirectional I/O architecture where all 16 pins default to HIGH at power-up, eliminating external pull-ups for input use. Its Fm+ I²C interface supports 1 MHz clocking with 30 mA SDA sink drive, enabling reliable communication on buses up to 4000 pF without repeaters.

Internal Power-On Reset (POR) and dedicated hardware RESET pin ensure deterministic initialization of I/O states and I²C state machine. Unlike the PCF8575, it replaces the open-drain INT output with an active-LOW RESET input - requiring system-level interrupt polling but enabling synchronous recovery across multiple expanders via shared reset line.

Key Specifications

Pinout & Package

Packaged in plastic thin shrink small outline package (TSSOP24), 24 leads, body width 4.4 mm (SOT355-1), with exposed pad not present - requires standard PCB land pattern per JEDEC MO-153.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCF8575T, PCA9671PW,112 delivers 2.5× faster I²C, 13× higher bus drive, and 4× total sink current - enabling dynamic LED control and scalable multi-node systems. Versus PCA9673PW, it trades interrupt capability for lower pin count and cost in reset-only applications.

Availability

PCA9671PW,112 is available at Aetrix Electronics and suitable for industrial control, server management, and medical equipment requiring stable component supply, extended temperature operation, and high-density I²C bus expansion.

Supply support for PCA9671PW,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 focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in interface and power management ICs.

The PCA9671PW,112 belongs to NXP's Fast-mode Plus I²C I/O expander family, designed specifically to replace legacy PCF8575 in high-speed, high-drive, and address-dense embedded systems.

FAQ

What is the primary function of the PCA9671PW,112 in an embedded system?

The PCA9671PW,112 serves as a 16-bit remote I/O expander that extends microcontroller GPIO via a 1 MHz Fast-mode Plus I²C interface. It provides quasi-bidirectional ports with 25 mA sink capability per pin and 400 mA total package sink - enabling direct LED driving, sensor interfacing, and actuator control without additional level-shifting or driver circuitry. Its RESET input and 64-address flexibility make it ideal for scalable industrial and server designs.

How does the PCA9671PW,112 differ from the PCF8575 in terms of reset and interrupt functionality?

The PCA9671PW,112 replaces the PCF8575's open-drain interrupt (INT) output with an active-LOW hardware RESET input. This change supports synchronized initialization across multiple expanders but removes hardware interrupt signaling - requiring software polling of input registers for event detection. The PCA9671PW,112 retains full backward compatibility in register mapping and I/O behavior otherwise.

Can the PCA9671PW,112 drive LEDs directly, and what are the current limits?

Yes, the PCA9671PW,112 can drive LEDs directly: each of its 16 I/O pins supports 25 mA sink current, and the total package sink capacity is 400 mA. This allows simultaneous illumination of up to 16 standard 25 mA LEDs. 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 are the voltage and temperature specifications for reliable operation of the PCA9671PW,112?

The PCA9671PW,112 operates over a supply voltage range of 2.3 V to 5.5 V and features 5.5 V-tolerant I/Os - allowing seamless integration with both 3.3 V and 5 V systems without level shifters. It is rated for continuous operation from −40 °C to +85 °C, meeting industrial and medical equipment environmental requirements. Internal Power-On Reset activates at VPOR, ensuring stable initialization across this full range.

How many unique I²C addresses does the PCA9671PW,112 support, and how are they configured?

The PCA9671PW,112 supports 64 unique I²C slave addresses (0x20 to 0xBE), selected using three address pins (AD0, AD1, AD2). These pins accept static logic levels (VDD/VSS) or dynamic signals (SCL/SDA) - enabling flexible addressing in multi-device systems. No internal pull-ups exist on these pins, so external biasing is mandatory. Reserved addresses (e.g., General Call 0x00, Device ID 0xFC) are excluded from user assignment to prevent bus conflicts.