PLURAL CHANNEL ANALOG-TO-DIGITAL CONVERTER, METHOD AND METER EMPLOYING AN INPUT CHANNEL WITH A PREDETERMINED DIRECT CURRENT BIAS

摘要

A meter for power lines includes first input channels having AC signals with DC values of about zero. A second input channel has an analog output with a predetermined non-zero DC bias value. Plural biasing and scaling circuits input the AC signals and output corresponding analog outputs. Plural analog-to-digital converters input the corresponding analog outputs and output corresponding digital values. A serial output circuit serially communicates the corresponding digital values for a first set of A/D conversions before serially communicating digital values for a subsequent second set of conversions without providing any synchronization of the corresponding digital values for both the first and second sets of conversions. A serial input circuit serially receives the serially communicated digital values and saves the same in a memory. A processor averages the digital values for the channels and determines whether only the average associated with the second channel has the DC bias value.