MICROCHIP MCP23S17-E/SS 16-Bit I/O Expander, SPI, 1.8V-5.5V, SSOP-28

The MICROCHIP MCP23S17-E/SS is a sophisticated 16-bit input/output (I/O) port expander designed to add general-purpose parallel I/O capabilities to systems utilising a Serial Peripheral Interface (SPI). It provides a flexible solution for microcontroller projects requiring additional digital pins, enabling control and monitoring of external devices.

Functionally organised as two 8-bit ports (PORTA and PORTB), the device can be configured via software to operate in either an 8-bit or a unified 16-bit mode. It features multiple 8-bit configuration registers for setting the direction (input or output), polarity, and data for each I/O pin. A system master can dynamically enable any I/O as an input or output by writing to the I/O configuration registers, with the data for inputs and outputs maintained in corresponding registers.

Key Features & Benefits

• SPI Serial Interface: Offers a high-speed, full-duplex communication link with the system master, supporting data rates up to 1.7MHz.
• Cascading Capability: Up to eight devices can be connected on the same SPI bus, allowing for expansion of up to 128 additional I/O lines from a single microcontroller.
• High Drive Capability: Each I/O pin can sink or source up to 25mA, providing ample current to directly drive LEDs, relays, or other peripherals.
• Wide Operating Voltage: Supports a broad supply voltage range from 1.8V to 5.5V, making it compatible with both modern low-voltage and legacy 5V logic systems.
• Polarity Control: The polarity of the input port register can be inverted via a dedicated register, simplifying logic level interpretation.
• Robust Design: Housed in a compact SSOP-28 package, it operates reliably across an extended industrial temperature range from -40°C to +125°C.

Ideal for a wide array of applications, this I/O expander is a fundamental component for adding digital expansibility in **<u