16-bit 2.3- to 5.5-V I2C/SMBus I/O expander with interrupt, weak pull-up & config registers

This 16-bit I/O expander for the

two-line bidirectional bus (I2C) is designed for 2.3-V to 5.5-V

VCC operation. It provides general-purpose remote I/O expansion for

most microcontroller families via the I2C interface [serial clock (SCL),

serial data (SDA)].

The PCA9555 consists of two 8-bit

Configuration (input or output selection), Input Port, Output Port, and Polarity

Inversion (active high or active low operation) registers. At power on, the I/Os are

configured as inputs. The system master can enable the I/Os as either inputs or

outputs by writing to the I/O configuration bits. The data for each input or output

is kept in the corresponding Input or Output register. The polarity of the Input

Port register can be inverted with the Polarity Inversion register. All registers

can be read by the system master.