MCU and Soc

A microcontroller (also microcomputer, MCU or µC) is a small computer on a single integrated circuit consisting internally of a relatively simple CPU, , , I/O ports, and memory. Program memory in the form of or is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for small or dedicated applications. Thus, in contrast to the used in and other high-performance or general purpose applications, simplicity is emphasized.

System-on-a-chip or system on chip (SoC or SOC) refers to integrating all components of a or other into a single integrated circuit (chip). It may contain , , mixed-signal, and often functions – all on one. A typical application is in the area of .

The contrast with a is one of degree. Microcontrollers typically have under 100K of RAM (often just a few KBytes) and often really are single-chip-systems; whereas the term SoC is typically used with more powerful processors, capable of running software such as or , which need external memory chips (flash, RAM) to be useful, and which are used with various external peripherals. In short, for larger systems System-on-a-chip is hyperbole, indicating technical direction more than reality: increasing chip integration to reduce manufacturing costs and to enable smaller systems. Many interesting systems are too complex to fit on just one chip built with a process optimized for just one of the system's tasks.

When it is not feasible to construct an SoC for a particular application, an alternative is a (SiP) comprising a number of chips in a single package. In large volumes, SoC is believed to be more cost effective than SiP since it increases the yield of the fabrication and because its packaging is simpler.

Another option, as seen for example in higher end cell phones and on the , is stacking during board assembly. The SoC chip includes processors and numerous digital peripherals, and comes in a ball grid package with lower and upper connections. The lower balls connect to the board and various peripherals, with the upper balls in a ring holding the memory busses used to access NAND flash and DDR2 RAM. Memory packages could come from multiple vendors.