Nexperia USA Inc. PCA9539PWJ

Overview

PCA9539PWJ from Nexperia is a low-voltage 16-bit I²C/SMBus GPIO expander with interrupt output, active-low reset pin, and configurable input/output registers. It operates from 2.3 V to 5.5 V, delivers ≤1 µA standby current, supports 400 kHz Fast-mode I²C, and features 5 V-tolerant I/Os. Used in ACPI power switches, sensor interfaces, LED/fan control, and keypad expansion where minimal interconnect and deterministic interrupt signaling are required.

For engineers reviewing the PCA9539PWJ datasheet, PCA9539PWJ pinout, PCA9539PWJ application, or PCA9539PWJ equivalent, key selection criteria include its dual 8-bit port architecture, hardware address pins (A0/A1), open-drain INT output timing (tv(INT)), reset recovery behavior, and polarity inversion register functionality for flexible signal conditioning.

Technical Context

The PCA9539 implements a two-port (P0/P1) parallel I/O expansion architecture controlled via I²C-bus, with independent configuration, input, output, and polarity inversion registers per port. Its state machine initializes on power-on reset or active-low RESET assertion, restoring all registers-including Configuration (0x06/0x07 defaulting to 0xFF) and Output (0x02/0x03 defaulting to 0xFF)-to known states.

Interrupt generation is edge-triggered on any configured input pin transition, latched until cleared by reading the corresponding Input Port register (0x00/0x01) or by return-to-idle state. The SCL/SDA inputs include Schmitt-trigger action (Vhys = 0.10 × VCC) and noise filtering, enabling robust operation in electrically noisy environments without external debouncing.

Key Specifications

Pinout & Package

TSSOP24 package (SOT355-1): plastic thin shrink small outline, 24 leads, 4.4 mm body width, rated for -40 °C to +85 °C ambient operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA6424A and PCA9555, the PCA9539PWJ uniquely combines hardware RESET, ultra-low 1 µA standby current, and edge-triggered interrupt-making it optimal for power-critical, safety-responsive designs where deterministic reset and low-latency wake are mandatory.

Availability

PCA9539PWJ is available at Aetrix Electronics and suitable for ACPI power management, sensor interface, LED/fan control, and keypad expansion requiring stable component supply across industrial, computing, and medical product lifecycles.

Supply support for PCA9539PWJ 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

Nexperia is a global semiconductor expert delivering high-performance, reliable, and energy-efficient components for automotive, industrial, and consumer applications.

The PCA9539 belongs to Nexperia's I²C GPIO expander product line, engineered specifically for low-power, interrupt-driven peripheral expansion in resource-constrained embedded systems with strict EMC and reliability requirements.

FAQ

What is the maximum sink current per I/O pin on the PCA9539PWJ?

Each I/O pin (P0_0–P0_7, P1_0–P1_7) supports up to 25 mA DC sink current in output mode, verified per datasheet Table 14 (IOL). This enables direct driving of LEDs or small relays without external buffers. Exceeding this limit risks thermal overstress or output stage degradation over time.

How does the interrupt (INT) pin behave after being triggered?

The INT pin goes low on any input pin edge transition and remains latched low until either the corresponding Input Port register (0x00 or 0x01) is read or the input returns to its original logic state. Reading the register clears the interrupt flag synchronously with the ACK/NACK pulse on SCL, as defined in Section 6.6 of the datasheet.

Can the PCA9539PWJ operate with a 3.3 V microcontroller while interfacing with 5 V peripherals?

Yes. All P0/P1 I/O pins are 5 V tolerant up to 6 V regardless of VCC (2.3–5.5 V), allowing safe connection to 5 V sensors or switches when VCC = 3.3 V. SCL/SDA remain 3.3 V compatible due to their internal level-shifting design and Schmitt-trigger inputs.

What happens to I/O states during power-up or RESET assertion?

At power-on reset or active-low RESET, all 16 I/Os default to high-impedance inputs, Configuration registers (0x06/0x07) load 0xFF, Output registers (0x02/0x03) load 0xFF, and INT is deasserted. No glitch occurs on I/O pins during this transition, ensuring safe startup in systems with attached loads.