NXP Semiconductors PCA9539PW,112

Overview

PCA9539PW,112 from NXP Semiconductors is a 16-bit I²C-bus GPIO expander with active-low interrupt and hardware reset, operating from 2.3 V to 5.5 V, featuring 5 V-tolerant I/Os, polarity inversion registers, and open-drain INT output - used in industrial control panels for remote sensor monitoring and LED status indication.

For engineers reviewing the PCA9539PW,112 datasheet, PCA9539PW,112 pinout, PCA9539PW,112 application, or PCA9539PW,112 equivalent, key selection criteria include I²C address configurability (A0/A1), RESET behavior (full register + state machine reset), low standby current, noise-filtered SCL/SDA inputs, and TSSOP24 package compatibility with 0.65 mm pitch PCB layouts.

Technical Context

The PCA9539PW,112 implements two independent 8-bit I/O ports (Port 0 and Port 1), each with dedicated configuration, input, output, and polarity inversion registers. Its I²C interface supports standard-mode (up to 100 kHz) and fast-mode (up to 400 kHz) operation, with internal noise filtering on SCL and SDA lines to suppress glitches.

Unlike the PCA9539R variant, the PCA9539PW,112 performs full device reset on active-low RESET assertion: both I/O configuration registers and the I²C state machine return to default states (all I/Os as inputs, outputs high), while retaining power-on reset immunity and no glitch during power-up.

Key Specifications

Pinout & Package

TSSOP24 package (SOT355-1), 24-pin, 4.4 mm body width, 0.65 mm lead pitch, exposed pad not present - suitable for compact industrial PCBs with manual or automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9539RPW,118 and PCA9555PW,112, the PCA9539PW,112 uniquely delivers full register reset on hardware RESET while omitting internal pull-ups - enabling lower power consumption and deterministic startup behavior in mission-critical industrial systems.

Availability

PCA9539PW,112 is available at Aetrix Electronics and suitable for industrial control panels, smart energy meters, building automation controllers, and automated test equipment requiring stable component supply across extended temperature ranges (−40 °C to +85 °C).

Supply support for PCA9539PW,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 over 50 years of analog and mixed-signal design expertise.

The PCA9539 product line delivers low-power, interrupt-capable I²C GPIO expansion for resource-constrained embedded systems - designed specifically for industrial HMI, metering, and control applications demanding robustness and long-term supply stability.

FAQ

What is the primary function of the PCA9539PW,112 in an embedded system?

The PCA9539PW,112 serves as a 16-bit I²C-bus GPIO expander that extends digital I/O capability for microcontrollers with limited native pins. It provides configurable input/output ports, polarity inversion, interrupt signaling on input changes, and hardware reset - enabling scalable, low-pin-count interface solutions in industrial and metering applications. The PCA9539PW,112 operates from 2.3 V to 5.5 V and supports 5 V-tolerant I/Os without level shifters.

How does the RESET pin behavior differ between PCA9539PW,112 and PCA9539RPW,118?

In the PCA9539PW,112, asserting the active-low RESET pin initializes both the I²C state machine and all internal registers (I/O configuration, output, polarity, input) to their power-on defaults - all 16 I/Os become inputs with high outputs. In contrast, PCA9539RPW,118 only resets the I²C state machine; its I/O registers retain prior values. This makes PCA9539PW,112 ideal for fail-safe recovery, while PCA9539RPW,118 suits applications requiring I/O state persistence. The PCA9539PW,112 requires a pull-up resistor on RESET.

Can the PCA9539PW,112 interface directly with 5 V peripherals when powered from 3.3 V?

Yes, the PCA9539PW,112 features 5 V-tolerant I/Os - meaning all 16 GPIO pins (IO0_0 through IO1_7) accept input voltages up to 5.5 V regardless of VDD level (2.3 V–5.5 V). When powered from 3.3 V, it can safely read 5 V logic signals from sensors or switches and drive 5 V LEDs (with appropriate current-limiting resistors), eliminating external level-shifting components. This capability is confirmed in the official NXP datasheet Rev. 9 section 2.

What I²C address options are supported by the PCA9539PW,112?

The PCA9539PW,112 uses a fixed 7-bit base address of 11101xx₂, where the two LSBs (xx) are set by hardware pins A0 and A1. With A0 and A1 tied to VDD or VSS, four unique addresses are possible: 0x70, 0x71, 0x72, or 0x73. This allows up to four PCA9539PW,112 devices on the same I²C bus without address conflict. The address is latched at power-up and remains static until reset - no software address programming is required.

Does the PCA9539PW,112 include internal pull-up resistors on its I/O pins?

No, the PCA9539PW,112 intentionally omits internal pull-up resistors - a key distinction from the PCA9555. This design reduces standby current when I/Os are held LOW, improving power efficiency in battery-operated or energy-sensitive applications like smart meters. External pull-up or pull-down resistors must be added as needed for specific signal integrity or logic-level requirements. This feature is explicitly stated in the General Description section of the NXP datasheet.