Analog Devices’ new energy metering ICs—the ADE7753 and ADE7758—are based on the company’s high-resolution analog-to-digital converter (ADC) technologies, combined with a fixed-function DSP. The DSP performs all the necessary energy measurement calculations, allowing a low-cost microprocessor to be used for data management and supervisory functions. This architecture simplifies meter designs that previously relied on microprocessors to perform complex computations. The reduction in extensive code development significantly reduces cost and time-to-market.
The ADE7758, which features second-order sigma-delta ADCs, is designed for midrange 3-phase energy meters. For each phase, the chip measures reactive, active, and apparent energy; as well as rms voltage and rms current. These measurements are accessed via a serial interface that allows a fully automated digital calibration. The ADE7758 interfaces with a variety of sensors, including current transformers and di/dt current sensors, such as Rogowski coils. Like other products in the ADE family, the ADE7758 provides accurate active energy measurements with less than 0.1% gain error over a current dynamic range of 1000-to-1. Its reactive energy measurement also surpasses the Class 2 IEC61268 accuracy requirement of VAR-hr meters.