Expand 3 click mikroBUS™ The Expand 3 click is an add-on board that uses a DS2408 chip to expand the number of I/O lines within your projects. The DS2408 has a 64-bit registration number which means that more than one Expand 3 click board can be used on the same 1-Wire data line. The board is suitable for a 3.3 V or 5 V power supply.