PCA9535DWR – I/O Expander 16-Bit I2C SMBus 400Khz SOIC-24

Resources:
Datasheet
16-Bit I2C Low-Power I/O Expander with Interrupt Output for Microcontroller GPIO Expansion
The PCA9535DWR is a 16-bit I/O expander designed to extend the GPIO capability of microcontrollers using the I2C or SMBus interface. It operates across a wide supply range from 2.3 V to 5.5 V, making it compatible with both 3.3 V and 5 V systems. With two 8-bit ports, configurable direction control, and register-based operation, it enables efficient remote I/O management in space-constrained embedded designs.
This device features an open-drain, active-low interrupt output that alerts the host controller whenever an input state changes, reducing constant bus polling and lowering system power consumption. The PCA9535DWR supports fast-mode I2C operation up to 400 kHz, offers 5 V tolerant I/O pins, and provides strong output drive capability suitable for directly driving LEDs. Its low standby current makes it well-suited for battery-powered and energy-sensitive applications.
Key Features

16-Bit GPIO Expansion: Two independent 8-bit I/O ports for flexible input/output control
I2C / SMBus Interface: Supports up to 400 kHz fast-mode communication
Low Power Consumption: Standby current as low as 1 uA (typical)
Interrupt Output: Open-drain active-low INT pin for efficient input change detection
Wide Supply Range: Operates from 2.3 V to 5.5 V
5 V Tolerant I/O: Safe interfacing with higher-voltage logic levels
Configurable Registers: Input, output, polarity inversion, and configuration registers
LED Drive Capability: High current sink/source for direct LED driving
Multiple Device Support: Three address pins allow up to 8 devices on the same I2C bus

Applications

Microcontroller GPIO Expansion: When native I/O pins are insufficient
Industrial Control Systems: Remote digital inputs and outputs
Embedded and IoT Devices: Low-power, space-efficient I/O control
LED and Keypad Interfaces: Direct driving and monitoring
Consumer Electronics: I/O management via serial bus