Isolated metrology chipset ensures energy meter magnetic immunity

October 02, 2012 // By Paul Buckley
Analog Devices, Inc., has introduced what the company claims is the industry’s first fully isolated metrology chipset designed for polyphase energy metering applications.

The ADE7978 metrology chipset includes the ADE7978 3-phase metrology IC combined with up to four ADE7933 fully isolated A/D converter ICs. The ADE7933 3-channel sigma-delta A/D converter incorporates Analog Devices’ patented iCoupler and isoPower technologies to implement isolated signal transfer and dc-to-dc power conversion across a 5 kV-rated insulation barrier.  This enables the use of shunt resistor sensing elements instead of current transformers (CTs), thereby providing immunity to magnetic field interference and tampering. The use of shunts instead of CTs also reduces system cost and size.

The ADE7978 computes active, reactive, and apparent energies for class 0.5 meters.  The same device also provides comprehensive power quality measurements including THD and supports flexible SPI, I2C, and HSDC serial interfaces.

Two versions of the  A/D converter IC are available: three channel (ADE7933) and two channel (ADE7932)

An integrated isoPower isolated dc-to-dc converter (ADE7933/ADE7932) enables real time compensation for shunt temperature drift using on-chip temperature sensors (ADE7978 and ADE7933/ADE7932).

Availability and Pricing

The ADE7978 3-phase metrology IC is available now in 28-Pin LFCSP and priced at $1.90 each in 1,000 quantities.

The ADE7933 3-channel isolated ADC is available now and priced at $5.71each in 1,000 quantities.  The ADE7932 2-channel isolated ADC is available now and priced at $5.42 each in 1,000 quantities.

The EVAL-ADE7978EBZ evaluation board for the ADE7978 energy metering chipset is now available and priced at $350.00.

More information about the ADE7978 energy metering chipset at