The MCP16331 INV Click Board™ works as a buck-boost voltage regulator, a switching regulator topology that combines principles of the buck conversion (step-down) and the boost conversion (step-up). A buck converter outputs voltage that is smaller than the input voltage (steps down the input voltage). A boost converter outputs voltage that is greater than the input voltage (steps up the input voltage).
By combining these two topologies, the MCP16331 INV Click Board™ is able to output a regulated DC voltage, which can be set in the code, for input voltage both greater and less than the output voltage.