This reference design provides accurate measurements of AC voltage and current inputs using a precision 16-bit SAR ADC over a wide input range: covering protection and measurement range (including sampling requirements of IEC 61850-9-2): simplifying system design and improving trip time performance and reliability. The analog input module (AIM) is isolated from the host processor using a digital isolator with an integrated power. For a limited function and cost optimized design approach: An AC AIM can be designed using only three TI products: reducing system cost and board size. The alarm feature identifies the AC analog input faults on a sample basis for faster fault detection. The ADC has an additional auxiliary channel to diagnose the supply output of the digital isolator. A 12-bit ADS8668 ADC with a gain amplifier can increase the dynamic range by using programmable internal ranges: further optimizing the system cost.