NXP Semiconductors PCA9539RPW,112

Overview

PCA9539RPW,112 from NXP Semiconductors is a 16-bit I²C-bus GPIO expander with active LOW interrupt and dedicated RESET pin, designed for low-power embedded I/O expansion in space-constrained applications. It operates from 3.0 V to 5.5 V, features 5 V tolerant I/Os, supports up to 400 kHz I²C clock, and defaults all 16 pins to high-impedance inputs at power-on reset - enabling immediate use in ACPI power switches, LED drivers, and sensor interface subsystems.

For engineers reviewing the PCA9539RPW,112 datasheet, PCA9539RPW,112 pinout, PCA9539RPW,112 application, or PCA9539RPW,112 equivalent, this device delivers deterministic I/O state retention during I²C bus recovery (via its PCA9539R-mode RESET), polarity inversion per port, noise-filtered SCL/SDA inputs, and register-level configuration of input/output direction and interrupt sensitivity - critical for reliable system monitoring and control in industrial and automotive subsystems.

Technical Context

The PCA9539RPW,112 implements two independent 8-bit I/O ports (Port 0 and Port 1), each with configurable direction (via Configuration registers 6 and 7), polarity inversion (Registers 4 and 5), and read-accessible input states (Registers 0 and 1). Its interrupt output activates only on input-state changes and clears upon reading the corresponding input port register - ensuring precise edge detection without spurious triggers.

Unlike the PCA9539, the PCA9539R variant (including PCA9539RPW,112) retains all general-purpose register contents during hardware RESET - resetting only the I²C state machine to restore bus communication while preserving I/O pin states. This avoids unintended signal transitions on connected peripherals during bus lockup recovery.

Key Specifications

Pinout & Package

TSSOP24 package (SOT355-1), 24-pin plastic thin shrink small outline, body width 4.4 mm, lead pitch 0.65 mm - optimized for compact PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar GPIO expander applications.

Compared with PCA9539PW,112 and TCA9539PWR, the PCA9539RPW,112 uniquely balances I²C bus recoverability and I/O continuity - its RESET pin restores communication without disrupting peripheral control states, making it optimal for fault-tolerant industrial interfaces where signal integrity during recovery is critical.

Availability

PCA9539RPW,112 is available at Aetrix Electronics and suitable for industrial sensor hubs, LED status panels, ACPI power management subsystems, and modular peripheral interface boards requiring stable component supply and long-term design-in support.

Supply support for PCA9539RPW,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, power management, and microcontroller technologies.

The PCA9539R family was developed to extend NXP's I²C GPIO portfolio with enhanced bus resilience - specifically addressing the need for non-disruptive I²C recovery in mission-critical embedded systems without sacrificing I/O flexibility or power efficiency.

FAQ

What is the key functional difference between PCA9539RPW,112 and PCA9539PW,112?

The PCA9539RPW,112 implements PCA9539R-mode RESET: only the I²C state machine resets, while Output, Configuration, and Polarity registers retain their last values. In contrast, PCA9539PW,112 performs a full register and state machine reset. This means PCA9539RPW,112 maintains configured I/O states during bus recovery - a critical advantage in systems where unintended pin transitions could trigger faults. The PCA9539RPW,112 thus avoids disruptive reinitialization that PCA9539PW,112 introduces.

Does PCA9539RPW,112 support 3.3 V microcontrollers with 5 V peripherals?

Yes. PCA9539RPW,112 operates from 3.0 V to 5.5 V and features 5 V tolerant I/Os - meaning its IO0_0–IO1_7 pins safely accept 5 V input signals even when VDD = 3.3 V. This eliminates level shifters when interfacing with 5 V sensors, switches, or LEDs while using a 3.3 V host MCU. The SDA and SCL lines also tolerate 5 V with appropriate pull-up placement, ensuring robust I²C communication across mixed-voltage domains.

How does the interrupt mechanism work in PCA9539RPW,112?

The PCA9539RPW,112 generates an active LOW open-drain interrupt (INT pin) when any input-configured I/O pin changes state relative to its corresponding Input Port register value. The interrupt remains asserted until the relevant Input Port register (Port 0 or Port 1) is read - clearing it automatically. Critically, reading one port does not clear interrupts from the other port, enabling independent monitoring. No external debounce is needed, as the interrupt is synchronized to the I²C clock domain and filtered against noise.

Can PCA9539RPW,112 drive LEDs directly?

Yes - PCA9539RPW,112 can sink or source current through its I/O pins when configured as outputs. Each pin supports ±25 mA (typical), sufficient for driving standard LEDs. For common-anode configurations, connect LED anodes to VDD and cathodes to I/O pins (sinking current); for common-cathode, use external pull-ups and configure pins as open-drain. Always verify voltage drop and current limits per the absolute maximum ratings table - and note that sustained high-current operation may affect thermal performance in TSSOP24 packaging.

What I²C address options are available for PCA9539RPW,112?

The PCA9539RPW,112 uses a fixed 7-bit base address of 11101xx₂, where the two LSBs (xx) are set by A0 and A1 pins. With A0 and A1 tied to VDD, GND, or left floating (per datasheet guidelines), four unique addresses are possible: 0x70, 0x71, 0x72, and 0x73. This allows up to four PCA9539RPW,112 devices - or combinations with PCA9539PW,112 or PCA9539R variants - on a single I²C bus without address collision, simplifying scalable I/O expansion in complex systems.