All of the devices have voltage regulators on them so a wide power supply range is tolerable. The POR is a module that holds the processor in reset until the VDD rail is verified to be at or above a specific voltage for a specified period of time. This allows the device to come alive after the input voltage is at a desirable and stable level. There is also a Reset pin which can be used to put, or hold, the processor in the Reset state. The VLS monitors the VDD rail of the device and generates a user selectable reset or interrupt signal to the processor. The threshold and output type and function is configurable by having the processor write the appropriate values to the appropriate control register. The BLD provides an output as a bit in a processor readable register that indicates if the VDD rail is above or below one of four selectable levels. The level is selected by the processor writing the appropriate value to the appropriate control register. ADCs convert analog inputs to digital values that the processor can read and react to. Comparators are functions that compare an analog input signal to a specific voltage and indicate if the input is above or below that value. The processor can set the specific voltage by writing to the appropriate control register.