NXP Semiconductors PCA9673DB,112

Overview

PCA9673DB,112 from NXP Semiconductors is a 16-bit remote I/O expander for Fast-mode Plus (Fm+) I²C-bus systems, providing quasi-bidirectional port expansion with interrupt and hardware reset functionality. It operates from 2.3 V to 5.5 V, delivers 25 mA sink per I/O, supports 1 MHz I²C communication, and features 400 mA total package sink capacity-enabling direct LED PWM dimming in signage and industrial control interfaces.

For engineers reviewing the PCA9673DB,112 datasheet, PCA9673DB,112 pinout, PCA9673DB,112 application, or PCA9673DB,112 equivalent, key selection considerations include its 1 MHz Fm+ I²C interface, active-low open-drain INT output, RESET input replacing PCF8575's A2 pin, 16 programmable slave addresses, and 25 mA per-pin sink capability for LED drive without external buffers.

Technical Context

The PCA9673DB,112 implements a quasi-bidirectional I/O architecture where all 16 ports (P00–P07, P10–P17) default to high-impedance inputs at power-up and support latched output mode with 25 mA sink per pin. Its I²C interface complies with Fast-mode Plus (1 MHz), Standard-mode (100 kHz), and Fast-mode (400 kHz), with SDA capable of sinking 30 mA into 4000 pF bus loads.

Interrupt generation is edge-triggered on any I/O state change, and the active-low open-drain INT output connects directly to microcontroller interrupt logic. Reset is supported via internal Power-On Reset (POR), external active-low RESET pin (pin 3 in SO24/TSSOP24), or software-initiated General Call sequence (00h + 06h).

Key Specifications

Pinout & Package

PCA9673DB,112 is supplied in SO24 (SOT137-1) package: plastic small outline, 24 leads, 7.5 mm body width, lead pitch 1.27 mm. Pin 1 = INT (active-low interrupt output); pin 3 = RESET (active-low hardware reset); pins 4–11 and 13–20 = 16 quasi-bidirectional I/Os (P00–P07, P10–P17); pins 21–24 = AD0, SCL, SDA, VDD; pin 12 = VSS.

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, PCA9673DB,112 delivers 2.5× faster I²C, 8.3× higher SDA drive, and 4× greater package sink capacity - enabling denser LED arrays and more robust bus topologies. Versus PCA9674BS,118, it trades HVQFN miniaturization for SO24 manufacturability and adds critical RESET pin for safety-critical restarts.

Availability

PCA9673DB,112 is available at Aetrix Electronics and suitable for LED signage, industrial PLCs, and medical equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for PCA9673DB,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.

The PCA9673 product line delivers high-speed, high-drive remote I/O expansion for resource-constrained microcontrollers in noise-sensitive and thermally constrained environments.

FAQ

What is the maximum I²C bus speed supported by the PCA9673DB,112?

The PCA9673DB,112 supports Fast-mode Plus (Fm+) I²C operation up to 1 MHz. This is double the 400 kHz limit of legacy expanders like the PCF8575 and enables faster LED dimming updates, reduced host polling latency, and improved responsiveness in time-critical industrial interfaces. The SDA pin sustains 30 mA sink capability even at this speed, ensuring reliable signal integrity on loaded buses.

Does the PCA9673DB,112 have a hardware reset pin, and how does it differ from the PCF8575?

Yes, the PCA9673DB,112 includes an active-low RESET pin (Pin 3 in SO24), which replaces the A2 address pin found on the PCF8575. This allows synchronous hardware reset independent of I²C bus state - critical for fail-safe recovery in industrial and medical systems. Unlike the PCF8575, which relies solely on Power-On Reset or software reset, the PCA9673DB,112 guarantees deterministic initialization under brownout or glitch conditions.

Can the PCA9673DB,112 directly drive LEDs, and what is its per-pin current capability?

Yes, the PCA9673DB,112 can directly drive LEDs with a guaranteed 25 mA sink current per I/O pin (P00–P07, P10–P17). This eliminates the need for external transistor drivers in many 3.3 V and 5 V applications. Its total package sink capacity is 400 mA, allowing all 16 outputs to operate simultaneously at full current - ideal for LED signage, status panels, and multi-channel indicator systems.

How many I²C slave addresses does the PCA9673DB,112 support, and how are they configured?

The PCA9673DB,112 supports 16 programmable I²C slave addresses using two address pins: AD0 (Pin 21) and AD1 (Pin 2). These pins accept static HIGH/LOW biasing (no internal pull-ups), selecting addresses from 28h to 5Eh in hexadecimal. This enables up to 16 devices on a single I²C bus without address conflicts - essential for modular I/O systems, server backplanes, and distributed control networks.

What is the function of the INT pin on the PCA9673DB,112, and how is it used in system design?

The INT pin on the PCA9673DB,112 is an active-low open-drain interrupt output that signals I/O state changes (rising or falling edges) to the host microcontroller. It enables event-driven operation - eliminating continuous I²C polling - and supports wired-OR connection of multiple PCA9673DB,112 devices to a single MCU interrupt line. This reduces CPU load and improves real-time responsiveness in applications like emergency stop monitoring or button press detection.