PCAL9555APW

Overview

The PCAL9555APW is a 16-bit I2C-bus and SMBus I/O expander designed for low-voltage applications ranging from 1.65V to 5.5V. It features Agile I/O enhancements including programmable output drive strength, latchable inputs, and integrated pull-up or pull-down resistors to reduce external component count. The device provides an active-low interrupt output to notify the host processor of input state changes without constant polling.

Why Choose This Part

This expander offers high flexibility with software-selectable push-pull or open-drain outputs and internal 100 kOhm resistors. It is a drop-in replacement for the standard PCA9555 and PCA9555A while adding interrupt masking and latching features to improve system performance. The ultra-low 1.5uA standby current makes it ideal for battery-operated devices.

Applications

Getting Started

Communicate with the device over I2C at speeds up to 400 kHz using the standard 7-bit addressing scheme. Ensure the A0, A1, and A2 pins are hard-wired to GND or VDD to set the hardware address. Many libraries for the PCA9555 are compatible, but for full functionality, utilize the additional registers for pull-up/down configuration and interrupt masking.

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