Nexperia USA Inc. NCA9539PWJ

Overview

NCA9539PWJ 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 across 1.65 V to 5.5 V, supports 400 kHz Fast-mode I²C, delivers up to 25 mA per I/O for direct LED drive, and features 5 V-tolerant I/Os. It serves as a slave device in microcontroller-based systems requiring remote I/O expansion-e.g., keypad scanning, sensor interface, and fan control-with minimal bus overhead.

For engineers reviewing the NCA9539PWJ datasheet, NCA9539PWJ pinout, NCA9539PWJ application, or NCA9539PWJ equivalent, key selection criteria include its dual 8-bit port architecture (P0/P1), hardware address pins A0/A1 enabling up to four devices on one bus, open-drain INT output for asynchronous event notification, and power-on/reset behavior ensuring deterministic initialization without software intervention.

Technical Context

The NCA9539PWJ implements a register-mapped I²C slave interface with eight dedicated 8-bit registers organized as four read/write pairs: Input Port (00h/01h), Output Port (02h/03h), Polarity Inversion (04h/05h), and Configuration (06h/07h). Its state machine initializes all 16 I/Os as high-impedance inputs at power-up or RESET assertion, and only pins configured as inputs generate interrupts on edge transitions.

Interrupt generation relies on asynchronous comparison between current port states and latched input register values; INT deasserts upon reading the triggering port or when the pin returns to its prior logic level. The internal power-on reset circuit monitors VCC against VPORR (~1.4 V typ.) and VPORF (~1.2 V typ.), while the external RESET pin provides synchronous reset with pull-up requirement and minimum active-low pulse width (tw(rst)).

Key Specifications

Pinout & Package

TSSOP24 package (SOT355-1), 24-pin plastic thin shrink small outline, 4.4 mm body width, 0.65 mm pitch. Pin 1 index located at top-left corner; pin 12 is GND; pin 24 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9539PWR and PCA9539DP, the NCA9539PWJ uniquely combines 5 V-tolerant I/Os, sub-3 µA standby current, and an integrated RESET pin - making it the only option qualified for robust, low-power, mixed-voltage industrial I/O expansion without auxiliary components.

Availability

NCA9539PWJ is available at Aetrix Electronics and suitable for industrial automation, sensor interface modules, and embedded keypad systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for NCA9539PWJ 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 focused on essential efficiency technologies, delivering high-performance, reliable, and scalable logic, analog, and MOSFET solutions for automotive, industrial, and consumer markets.

The NCA9539 belongs to Nexperia's low-power I²C GPIO expander product line, engineered specifically for space-constrained, energy-sensitive applications needing deterministic I/O expansion with minimal firmware overhead and robust electrical behavior.

FAQ

What is the minimum VCC required for reliable I²C communication?

The NCA9539PWJ guarantees full I²C functionality down to 1.65 V VCC. Below this threshold, the internal power-on reset remains active and I²C transactions will not complete. At 1.65 V, the 400 kHz Fast-mode timing specifications-including setup/hold times for SDA and SCL-are fully met per the datasheet, provided external pull-up resistors are sized appropriately for bus capacitance.

How does the interrupt output behave when multiple inputs change simultaneously?

INT asserts on the first detected edge transition among any enabled input pin and remains asserted until the host reads the corresponding Input Port register (00h or 01h) or the pin returns to its pre-transition state. Simultaneous changes do not cause multiple pulses; INT stays active until cleared by either method, ensuring no event loss even under burst input activity.

Can the NCA9539PWJ drive LEDs directly without external current-limiting resistors?

No - external current-limiting resistors are mandatory. While the NCA9539PWJ supports up to 25 mA per I/O, exceeding absolute maximum ratings or operating outside recommended conditions (e.g., driving LEDs without series resistance) risks thermal damage or latch-up. Resistor value must be selected based on forward voltage, desired LED current, and VCC level per Ohm's Law.

Is the RESET pin necessary if power sequencing is tightly controlled?

Yes - RESET provides deterministic recovery from software hangs or I²C bus lockups independent of power rail behavior. Even with clean power sequencing, firmware errors or bus contention can leave the device in an undefined state; asserting RESET restores all registers and I/Os to known defaults without requiring a full power cycle, improving system reliability in unattended operation.