This reference design implements Class 0.1 split-phase energy measurement using high-performance, multi-channel analog-to-digital converters (ADC). The independent ADC samples the output of current transformers (CT) at 8 kHz to measure the current and voltage of each leg of the AC mains. The reference design can achieve high accuracy across a wide input current range (0.05 – 100 amps) and supports high sampling frequencies necessary for advanced power quality features such as individual harmonic analysis. Using an independent ADC to sample the CT output provides designers greater flexibility in the choice of metrology microcontrollers when compared to integrated SoCs and dedicated application-specific products. The reference design uses a SimpleLink™ ARM Cortex-M4 host microcontroller to calculate energy measurement parameters. This design can also use an ADC sample rate of 32 ksps by only enabling a subset of the full energy measurement parameters.
- Split-phase metrology for electricity meters that meets ANSI C12.20 Class 0.1 active energy accuracy requirements across 10000:1 input range
- Active and reactive energy and power, root mean square (RMS) current and voltage, power factor, and line-frequency calculations
- Isolated RS-232 and RS-485 with 5-kV RMS isolation
- Communications module expansion with current limit and overvoltage and undervoltage protection
- Tested across 50-mA to 100-A input range
- Complete, tested reference design with hardware files and design guide
- High active energy accuracy still obtained when ADC sample rate increased to 32 ksps