Microchip I/O Expander SPI 28-Pin SSOP, MCP23S17T-E/SS

The Microchip 16 bit general purpose parallel I/O expansion for I2C bus or SPI applications. Its consists of multiple 8 bit configuration registers for input, output and polarity selection. The system master can enable the I/Os as either inputs or outputs by writing the I/O configuration bits. The data for each input or output is kept in the corresponding input or output register.

16 bit input/output port expander with interrupt output
Cascadable for up to 8 devices on one bus
25mA sink/source capability per I/O
Supports up to 10MHz SPI™ clock speeds