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More accurate readings of total energy promised with metering ICs

ADI's next-generation metering chips now measure “reactive” energy for more precise readings of energy usage

Analog Devices' new energy metering ICs — the ADE7753 and ADE7758 — now allow utility companies to obtain more accurate energy usage information than ever before. Reactive energy, caused by nonlinear loads, requires energy suppliers to supply more volt-amps to customers than they can measure with a conventional watt-hour (active energy)
meter. The ability to measure reactive energy enables utility companies to prevent revenue loss and improve power-generation capacity management.

Like all of Analog Devices' energy ICs, the ADE7753 and ADE7758 are based on ADI'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 mid-range three-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 percent gain error over a current dynamic range of 1000:1. Its reactive energy measurement also surpasses the Class 2 IEC61268 accuracy requirement of VAR-hr meters.

The ADE7758 consumes 70 mW, while the ADE7753, for single-phase connections, consumes only 25 mW. Both devices are designed to operate over a temperature range of minus 40 degrees C to 85 degrees C and require a single 5-volt supply. To facilitate migration from existing designs to new meter designs, the ADE7753 and ADE7758 are pin-to-pin
compatible with previously released ICs in the ADE family.

The ADE7753 is available in a 20-lead SSOP package and is priced at $2.52 per unit in 1,000-piece quantities. Available in a 24-lead SOIC package, the ADE7758 is priced at $6.88 per unit in 1,000-piece quantities. Evaluation and software kits are available to facilitate performance and functionality verification. Both devices are available in production volume quantities.

Analog Devices, Inc., 804 Woburn, Wilmington, MA 01887. Tel: 800-262-5643

7753 data sheet

7758 data sheet

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