ADE7933 datasheet(5/125 Pages) AD

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Data Sheet

ADE7978/ADE7933/ADE7932/ADE7923

Rev. D | Page 5 of 125

GENERAL DESCRIPTION

The ADE7978, the ADE7933/ADE7932, and ADE7923 form a

chipset dedicated to measuring 3-phase electrical energy using

shunts as current sensors.

The ADE7933/ADE7932 are isolated, 3-channel sigma-delta

analog-to-digital converters (Σ-Δ ADCs) for polyphase energy

metering applications that use shunt current sensors. The

ADE7923 is a nonisolated, 3-channel Σ-Δ ADC for the neutral line

that uses a shunt current sensor. The ADE7932 features two ADCs,

and the ADE7933 and ADE7923 feature three ADCs.

One channel is dedicated to measuring the voltage across the

shunt when a shunt is used for current sensing. This channel

provides a signal-to-noise ratio (SNR) of 67 dB over a 3.3 kHz

signal bandwidth. Up to two additional channels are dedicated

to measuring voltages, which are usually sensed using resistor

dividers.

The unused voltage channels on the neutral ADE7923 can be

used for auxiliary voltage measurements. These channels provide

an SNR of 75 dB over a 3.3 kHz signal bandwidth. One voltage

channel can be used to measure the temperature of the die via

an internal sensor.

The ADE7933 and ADE7923 include three channels: one

current channel and two voltage channels. The ADE7932

includes one current channel and one voltage channel, but is

otherwise identical to the ADE7933.

The ADE7933/ADE7932 include isoPower®, an integrated,

isolated dc-to-dc converter. Based on the Analog Devices, Inc.,

iCoupler® technology, the dc-to-dc converter provides the

regulated power required by the first stage of the ADCs at a

3.3 V input supply. The ADE7933/ADE7932 eliminate the need

for an external dc-to-dc isolation block. The iCoupler chip scale

transformer technology is used to isolate the logic signals

between the first and second stages of the ADC. The result is a

small form factor, total isolation solution. The ADE7923 is the

nonisolated version of the ADE7933 that can be used for

neutral current measurement when isolation from the neutral

line is not required.

The ADE7933/ADE7932 and ADE7923 contain a digital interface

that is specially designed to interface with the ADE7978. Using

this interface, the ADE7978 accesses the ADC outputs and

configuration settings of the ADE7933/ADE7932 and

ADE7923.

The ADE7933/ADE7932 are available in a 20-lead, Pb-free, wide-

body SOIC package with increased creepage. The ADE7923 is

available in a similar 20-lead, Pb-free, wide-body SOIC package

without the increased creepage.

The ADE7978 is a high accuracy, 3-phase electrical energy

measurement IC with serial interfaces and three flexible pulse

outputs. The ADE7978 can interface with up to four ADE7933/

ADE7932 and ADE7923 devices. The ADE7978 incorporates all

the signal processing required to perform total (fundamental and

harmonic) active, reactive, and apparent energy measurement

and rms calculations, as well as fundamental-only active and

reactive energy measurement and rms calculations. A fixed

function digital signal processor (DSP) executes this signal

processing.

The ADE7978 measures the active, reactive, and apparent energy

in various 3-phase configurations, such as wye or delta services,

with both three and four wires. The ADE7978 provides system

calibration features for each phase, gain calibration, and optional

offset correction. Phase compensation is also available, but it is

not necessary because the currents are sensed using shunts. The

CF1, CF2, and CF3 logic outputs provide a wide selection of

power information: total active, reactive, and apparent powers;

the sum of the current rms values; and fundamental active and

reactive powers.

The ADE7978 incorporates power quality measurements, such

as short duration low or high voltage detection, short duration

high current variations, line voltage period measurement, and

angles between phase voltages and currents. Two serial interfaces,

SPI and I2C, can be used to communicate with the ADE7978.

A dedicated high speed interface—the high speed data capture

(HSDC) port—can be used in conjunction with I2C to provide

access to the ADC outputs and real-time power information.

The ADE7978 also has two interrupt request pins, IRQ0 and

IRQ1, to indicate that an enabled interrupt event has occurred.

The ADE7978 is available in a 28-lead, Pb-free LFCSP package.

Note that throughout this data sheet, multifunction pins, such

as SCLK/SCL, are referred to by the entire pin name or by a

single function of the pin, for example, SCLK, when only that

function is relevant.

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