The ADC integrated into the Si890x is specified with +/- 1 LSB of error for both integral nonlinearity and differential nonlinearity. This allows for accurate and precise 10-bit measurements. The 3-channel MUX on the input is an important feature because it allows multiple measurements to be taken with a single device. For AC mains line monitoring, this means that voltage and current can be measured with a single device. Furthermore, voltage and current measurements for all three phases of a 3-phase system can be made with just two devices. A selectable ADC reference allows the user to choose the VDDA as a convenient reference. Alternatively, the dedicated VREF pin allows an external, high-quality reference to be used. All features are set using a programmable configuration register. The configuration command also provides selections between two different conversion modes for the ADC. It can either be operated in an on-demand mode where the conversion starts at the demand of a master controller, or in a burst/continuous mode where the ADC constantly makes conversions and sends the data to the bus.