Analog Devices Inc.United States

The ADE7757 is an accurate electrical energy measurement integrated circuit. It is a pin reduction version of ADE7755 with an enhancement of a precise oscillator circuit that serves as a clock source to the chip. The ADE7757 eliminates the cost of an external crystal or resonator, thus reducing the overall cost of a meter built with this IC. The chip directly interfaces with shunt resistor. The ADE7757 provides instantaneous and average real power based on line current and voltage. The part specifications surpass the accuracy requirements as quoted in the IEC61036 standard. The only analog circuitry used in the ADE7757 is in the ADCs and reference circuit. All other signal processing (e.g., multiplication and filtering) is carried out in the digital domain. This approach provides superior stability and accuracy over extremes in environmental conditions and over time. The small analog input full-scale allows the chip to interface to low value shunt resistances without losing dynamic range. The ADE7757 is available in 16-lead SOIC narrow-body package. The Application Note AN-679 can be used as a basis for a description of an IEC61036 low cost, watt-hour meter reference design. NOTE: For polyphase system designs, the ADE7752A is recommended.