NXP Semiconductors PCA9673DK,118

Overview

PCA9673DK,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, active-low open-drain interrupt (INT), and hardware RESET input. It operates from 2.3 V to 5.5 V, supports 1 MHz I²C-bus communication, and delivers 400 mA total package sink capacity-enabling direct LED PWM dimming in signage and industrial HMI applications.

For engineers reviewing the PCA9673DK,118 datasheet, PCA9673DK,118 pinout, PCA9673DK,118 application, or PCA9673DK,118 equivalent, this device serves as a drop-in upgrade over PCF8575 with higher bus speed, greater drive strength, expanded slave addressing (16 options), and integrated reset functionality-critical for robust embedded I/O expansion where bus loading, timing margin, and fault recovery matter.

Technical Context

The PCA9673DK,118 implements a quasi-bidirectional I/O architecture with latched outputs and internal pull-up current sources (I_trt(pu) = 100 µA), enabling fast rising edges on heavily loaded lines without external components. 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.

Interrupt generation is edge-triggered on any port input change (rising or falling), and the INT line is automatically cleared upon read/write access to the triggering port or when port state reverts to its prior value. Reset is supported via both internal Power-On Reset (POR), external active-low RESET pin (t_w(rst) min), and software-initiated General Call sequence (00h + 06h).

Key Specifications

Pinout & Package

PCA9673DK,118 is supplied in HVQFN24 (4 × 4 × 0.85 mm) package with exposed thermal pad. Pin 1 is index-marked; VSS connects to both pin 9 and the center thermal pad, which 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 PCF8575T/3,118, PCA9673DK,118 delivers 2.5× higher I²C bandwidth and 4× sink capacity-critical for real-time LED control. Versus PCA9674BS,118, it trades advanced interrupt features for lower gate count and reduced firmware complexity in basic I/O expansion roles.

Availability

PCA9673DK,118 is available at Aetrix Electronics and suitable for industrial control, medical equipment, and LED signage requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for PCA9673DK,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 applications, with deep expertise in I²C peripherals and embedded interface IP.

The PCA9673DK,118 belongs to NXP's Fast-mode Plus I²C I/O expander product line, designed specifically for high-reliability embedded systems needing scalable, interrupt-driven digital I/O expansion with minimal MCU resource overhead.

FAQ

What is the maximum I²C bus speed supported by PCA9673DK,118?

The PCA9673DK,118 supports Fast-mode Plus (Fm+) I²C operation up to 1 MHz, significantly exceeding the 400 kHz limit of legacy expanders like PCF8575. This enables faster I/O updates for time-sensitive applications such as LED PWM dimming and real-time sensor polling. The SDA line is rated for 30 mA sink into 4000 pF buses, ensuring signal integrity at full speed. PCA9673DK,118 maintains backward compatibility with Standard-mode (100 kHz) and Fast-mode (400 kHz) hosts.

How does the RESET pin on PCA9673DK,118 differ from the PCF8575?

Unlike the PCF8575-which uses pin 2 (A2) as a third address bit-the PCA9673DK,118 replaces A2 with an active-low hardware RESET input (pin 24). This allows synchronous system-level reset of I/O states without relying on I²C bus availability. Holding RESET low for t_w(rst) (min 100 ns) forces all ports to high-impedance inputs and clears internal registers. PCA9673DK,118 retains Power-On Reset and software reset via General Call (00h + 06h) for comprehensive fault recovery.

Can PCA9673DK,118 directly drive LEDs, and what is its total current limit?

Yes, PCA9673DK,118 can directly drive LEDs with 25 mA sink capability per I/O pin (P00–P07, P10–P17), eliminating external driver transistors in most designs. Its total package sink capacity is 400 mA-sufficient to activate all 16 outputs simultaneously at full 25 mA. This makes PCA9673DK,118 ideal for LED signage, status indicators, and backlight control. Thermal design must ensure junction temperature remains within −40 °C to +85 °C limits under sustained load.

What is the function of the INT pin on PCA9673DK,118, and how is it triggered?

The INT pin on PCA9673DK,118 is an active-low open-drain interrupt output that signals port state changes to the host microcontroller. It triggers on any rising or falling edge at any input-capable I/O pin, reducing I²C polling overhead. The interrupt is automatically cleared when the host reads or writes the affected port, or when the port reverts to its original logic level. PCA9673DK,118 supports wired-OR connection of multiple devices to a single MCU IRQ line, enabling scalable I/O monitoring.

How many I²C slave addresses does PCA9673DK,118 support, and how are they configured?

PCA9673DK,118 supports 16 unique I²C slave addresses, selected using AD0 and AD1 pins (pins 18 and 23). Each pin accepts VDD or VSS to set binary combinations (00 to 11), yielding four base addresses (28h, 2Ah, 2Ch, 2Eh), each with four variants depending on SCL/SDA biasing-totaling 16 options. No internal pull-ups exist on AD0/AD1, so external resistors are required. Reserved addresses (General Call 00h, Device ID F8h–FBh) must be avoided to prevent bus conflicts. PCA9673DK,118 ensures reliable multi-device I²C networks without address collisions.