This diagram shows the major function blocks of a typical on-chip H8 MCU D/A converter. As the illustration shows, it is a very simple circuit based on an 8-bit R-2R circuit. There are actually two identical circuits in the D/A function block, each of which has its own individual output pin. Aside from some shared control register bits, the two converters operate independently. Two independent 8-bit data registers store the values to be converted. The only other circuit elements are the D/A Control Register (DACR) and the control circuit it drives. Notice that there are separate connections for AVref, AVcc, and AVss. This is done to primarily provide some isolation between the digital circuits on the microcontroller and the analog circuits in the D/A. The separate connections also provide added system design flexibility. Finally, the diagram shows the connection from the Module Stop register to the control circuit. It’s used in power-saving modes to enable and disable the D/A.