The rationale behind a voltage references are to produce a precise DC voltage even in the presence of substantial temperature and power supply variation. These reference voltages are not typically meant to source or sink significant amounts of current, but they are often used to provide a reference to a regulator circuit. This could use feedback to source current while maintaining the supply voltage at the same level as the reference. Voltage references are used in many other circuits such as analog to digital converters, data communication systems, and nearly all analog circuits.