NXP Semiconductors PCA9674PW,112

Overview

PCA9674PW,112 from NXP Semiconductors is an 8-bit quasi-bidirectional I/O expander for Fast-mode Plus (Fm+) I²C-bus systems, operating from 2.3 V to 5.5 V with 5.5 V-tolerant I/Os. It delivers 1 MHz I²C communication, 25 mA per port sink capability for direct LED driving, active-low open-drain interrupt output, and 64 programmable slave addresses via AD0–AD2 pins. It is used in LED signage, industrial PLCs, and keypad monitoring where remote GPIO expansion with low standby current (4.5 µA typical) is required.

For engineers reviewing the PCA9674PW,112 datasheet, PCA9674PW,112 pinout, PCA9674PW,112 application, or PCA9674PW,112 equivalent, key selection considerations include its Fm+ I²C interface compliance, 25 mA per-port sink drive, interrupt-driven input change detection, and TSSOP16 package compatibility with space-constrained embedded control designs.

Technical Context

The PCA9674PW,112 implements a quasi-bidirectional I/O architecture with no direction register-each of the eight ports (P0–P7) functions as input or output based on register write value and external voltage state. At power-up, all ports default to inputs with a 100 µA weak pull-up to VDD.

Its interrupt logic asserts the active-low INT pin when any input port state differs from its corresponding register value, enabling efficient event-driven polling avoidance. The device supports Software Reset via General Call address (00h) + data byte 06h and provides a 24-bit read-only Device ID containing manufacturer, part ID, and revision fields.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 4.4 mm body width, 0.65 mm pitch, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9674D,512 and PCA9674BS,118, the PCA9674PW,112 offers the optimal balance of compactness (TSSOP16), manufacturability (lead-free, standard tube packaging), and thermal performance for mid-volume industrial control designs - avoiding SO16's size penalty and HVQFN's assembly complexity.

Availability

PCA9674PW,112 is available at Aetrix Electronics and suitable for LED signage, industrial PLCs, and medical keypad interfaces requiring stable component supply across extended product lifecycles.

Supply support for PCA9674PW,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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The PCA9674 product line was designed to extend microcontroller GPIO resources over I²C in space- and power-constrained embedded systems - emphasizing interrupt-driven efficiency, high-current drive, and scalable multi-device addressing.

FAQ

What is the maximum I²C bus speed supported by the PCA9674PW,112?

The PCA9674PW,112 supports Fast-mode Plus (Fm+) I²C operation up to 1 MHz. This is confirmed in the NXP datasheet Rev. 7 (May 2013), Section 1 "General description", and enables high-speed communication without bus buffers on capacitances up to 4000 pF. The PCA9674PW,112 achieves this using enhanced SDA drive strength (30 mA sink) and internal clock filtering.

Does the PCA9674PW,112 require external pull-up resistors on its I²C lines?

Yes, the PCA9674PW,112 requires external pull-up resistors on both SCL and SDA lines, as stated in Section 6.2 "Pin description" and Figure 13 of the datasheet. Its SDA pin has 30 mA sink capability but no internal pull-up; SCL is input-only. Pull-up values depend on bus speed and capacitance - typical values are 2.2 kΩ for 1 MHz operation with ≤400 pF load.

How does the interrupt (INT) pin of the PCA9674PW,112 behave during power-up?

At power-up, the PCA9674PW,112's INT pin is released (high-impedance) after the internal Power-On Reset completes. Since all ports default to inputs with 100 µA pull-ups, INT remains deasserted unless an external signal drives any P0–P7 low before the first register read. The INT pin is active-low open-drain and requires an external pull-up resistor to function correctly in the PCA9674PW,112 system.

Can the PCA9674PW,112 drive LEDs directly without current-limiting resistors?

No, the PCA9674PW,112 cannot drive LEDs without external current-limiting resistors. Although it provides 25 mA sink per port, the LED forward voltage and supply rail must be considered. Per Section 1 and Figure 12, LEDs must be connected anode-to-VDD with cathode-to-Px, using a series resistor to set current. Omitting the resistor risks exceeding absolute maximum ratings and damaging the PCA9674PW,112 output stage.

What is the purpose of the Software Reset function in the PCA9674PW,112?

The Software Reset function returns the PCA9674PW,112 to its Power-On Reset state - clearing all registers and reinitializing I/Os as inputs with 100 µA pull-ups. It is executed via I²C General Call address (00h) followed by data byte 06h, as defined in Section 7.2.1. This allows remote recovery without hardware reset, and is fully supported in the PCA9674PW,112's Fm+ interface implementation.