PCA9555BS

Overview

The PCA9555BS is a 16-bit I2C and SMBus I/O expander designed to provide remote GPIO expansion for microcontrollers via a two-wire bidirectional bus. It features a polarity inversion register, an interrupt output to signal input state changes, and a low standby current of 1.1 uA. This device is particularly useful when additional I/O is required while keeping interconnections to a minimum.

Why Choose This Part

The device offers a wide operating voltage range from 2.3V to 5.5V and features internal noise filters on SCL and SDA inputs for robust communication. It minimizes system overhead by defaulting all 16 pins to inputs upon power-up and includes an internal power-on reset to prevent glitches. The HVQFN24 package provides a compact 4mm x 4mm footprint suitable for high-density PCB designs.

Applications

Getting Started

Integration requires connecting the SCL and SDA lines to an I2C master with appropriate pull-up resistors and configuring the three hardware address pins to set the unique bus address. Software development involves writing to the Configuration register to set pin direction and reading from the Input Port register to poll pin states. Engineers can use standard I2C libraries available for platforms like Arduino or Raspberry Pi for rapid prototyping.

Also Consider

MCP23017 MCHPMicrochip Technology - A widely used 16-bit I2C expander that includes internal pull-up resistors which can simplify the BOM.

TCA9555 TITexas Instruments - A pin-to-pin compatible alternative that often provides lower voltage operation support down to 1.65V.

PCAL9555A NXP Semiconductors - An agile I/O version of the PCA9555 that adds features like programmable pull-up/pull-down resistors and output drive strength control.

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