AD71056集成式电能计量集成电路振荡器和反极性指示

　　The AD710561 is a high accuracy， electrical energy metering IC with a precise oscillator circuit that serves as a clock source to the chip. The AD71056 eliminates the need for an external crystal or resonator， thus reducing the overall cost of building a meter with this IC. The chip directly interfaces with the shunt resistor. The AD71056 specifications surpass the accuracy requirements as quoted in the IEC62053-21 standard. The only analog circuitry used in the AD71056 is in the Σ-Δ ADCs and reference circuit. All other signal processing， such as multiplication and filtering， is carried out in the digital domain. This approach provides superior stability and accuracy over time and in extreme environmental conditions. The AD71056 supplies average real power information on F1 and F2， the low frequency outputs. These outputs either directly drive an electromechanical counter or interface with an MCU. The high frequency CF logic output， ideal for calibration purposes， provides instantaneous real power information. The AD71056 includes a power supply monitoring circuit on the VDD supply pin. The AD71056 remains inactive until the supply voltage on VDD reaches approximately 4 V. If the supply falls below 4 V， the AD71056 also remains inactive and the F1， F2， and CF outputs are in their nonactive modes. Internal phase matching circuitry ensures that the voltage and current channels are phase matched， and the HPF in the current channel eliminates dc offsets. An internal no load threshold ensures that the AD71056 does not exhibit creep when no load is present. The part is available in a 16-lead， narrow body SOIC package.