The Maxim MAXQ3180 analogue front-end IC for polyphase electric meters measures and calculates voltage, current, power, energy, and all major power quality parameters. It integrates an 8-channel A/D converter and the company's dedicated, high-performance MAXQ microprocessor for computing a large set of polyphase multifunction energy metering parameters. Six of the input channels are dedicated to three-phase voltages and currents. One channel is dedicated to neutral-line current monitoring, and the eighth channel is for on-chip temperature monitoring.
The front-end IC can calculate apparent and reactive energy and power for each phase and the combined three-phase system, power factor, line frequency, and the voltage component of up to the 21st harmonic. Overall, the chip features a measurement error of less than 0.1% over a dynamic range of 100:1 at +25 °C, less than 0.2% error for reactive energy, and better than 0.5% accuracy for RMS voltage and RMS current. This is better than all relevant international standards for electricity metering (IEC 62053-21, IEC 62053-22 and IEC 62053-23).
The chip provides two configurable pulse outputs (typically for active and reactive energy) that can be set to output any of a large array of operational parameters. The MAXQ3180 interfaces with a host microcontroller via the standard SPI protocol.
The MAXQ3180 provides a full complement of protection/monitoring features, including overvoltage and overcurrent, voltage sag, and power-fail detection. In typical operation, it draws 10 mW (typical) with a 3.3-V supply voltage.
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