It's a balancing act for general-purpose I/O expander

To help designers to balance system performance with the processor and board overhead in sensor, control, and LED-displays applications, Catalyst Semiconductor came up with CAT9555 I/O bus expander. The 16bit device enables cost-effective I²C or SMBus general-purpose I/O expansion for most microcontroller families.

The CAT9555 comprises two 8bit ports (16 I/O pins), which power up as inputs and can be configured as an input or output by writing to a register. The fixed part of the I²C slave address is the same as the company's earlier 8bit device (CAT9554), allowing for any combination of up to eight I/O expanders to be connected on the same bus. This commonality provides designers with the flexibility to control the exact number of functions their system requires.

The CAT9555 comes in three RoHS-compliant package options: 24-lead SOIC, 24-pin TSSOP, and 24-pad 4-by-4mm TQFN. All packages operate over the industrial operating temperature range of -40° to +85°C.