The MonoStack high-density, double data rate (DDR) SDRAM stacked components are available in 128-, 256- or 512-Mb versions. They consist of two standard DDR SDRAM TSOPs, that stacked together have the same footprint as a single DDR SDRAM component. The stacked components are drop-in replacements for existing memory devices. The pins on the stacked components match that of comparable density monolithic components and do not require any modification or changes in lead formation. The TSOPs are separated from each other with an air gap that acts as thermal insulation preventing the up chip from dissipating heat to the lower chip. The DDR SDRAM uses a 2.5V supply for I/O and core power and has evolved from the industry-standard PC100 and PC133 SDRAM. The module has been approved by JEDEC as a 184-pin registered DIMM and a 184-pin unbuffered DIMM, with a 200-pin SODIMM standard under consideration.