ADE7816 datasheet(24/48 Pages) AD

24 / 48 page

ADE7816

Data Sheet

Rev. 0 | Page 24 of 48

ENERGY CALIBRATION

CHANNEL MATCHING

The ADE7816 provides individual channel gain registers that

allow the six current channels and the voltage channel to be

matched. Matching the channels simplifies the calibration process.

The IAGAIN (Address 0x4381), IBGAIN (Address 0x4382),

ICGAIN (Address 0x4383), IDGAIN (Address 0x4384),

IEGAIN (Address 0x4385), and IFGAIN (Address 0x4386)

registers adjust the A through F current channels, respectively,

whereas the VGAIN register (Address 0x4380) can be used to

adjust the voltage channel. The default value of the IxGAIN

registers is 0x00000, which corresponds to no channel gain. The

IxGAIN can adjust the channel gain by up to ±100%. The channel

is scaled by −50% by writing 0xC00000 to the corresponding

IxGAIN register, and it is increased by +50% by writing 0x400000.

Equation 7 shows the relationship between the IxGAIN register

and the rms measurement.

Irms = Irms

0 ×

⎟

⎠

⎞

⎜

⎝

⎛ +

IxGAIN

(7)

Vrms = Vrms

0 ×

⎟

⎠

⎞

⎜

⎝

⎛ +

VGAIN

where Irms

0 and Vrms0 are the current and voltage rms

measurements, respectively, without offset correction.

Changing the content of the IxGAIN registers affects all calcu-

lations based off that channel, including the active and reactive

energy. Therefore, it is recommended that the channel matching

be performed first in the calibration procedure.

ENERGY GAIN CALIBRATION

The active and reactive energy measurements can be calibrated

on all six channels separately. This separate calibration allows

compensation for meter-to-meter gain variation.

The AWGAIN register (Address 0x4391) controls the active

power gain calibration on Current Channel A. The BWGAIN

(Address 0x4393), CWGAIN (Address 0x4395), DWGAIN

(Address 0x4397), EWGAIN (Address 0x4399), and FWGAIN

(Address 0x439B) registers control the active power gain calibra-

tion on the B through F current channels, respectively. The default

value of the xWGAIN registers is 0x00000, which corresponds to

no gain calibration. The xWGAIN registers can adjust the active

power by up to ±100%. The output is scaled by −50% by writing

0xC00000 to the watt gain registers, and it is increased by +50%

by writing 0x400000 to them. Equation 8 shows the relationship

between the gain adjustment and the xWGAIN registers.

Active Power = Active Power0 ×

⎟

⎠

⎞

⎜

⎝

⎛

+ 1

800000

xWGAIN

(8)

Similar gain calibration registers are available for the reactive

power. The reactive power on Current Channel A can be gain

calibrated using the AVARGAIN (Address 0x439D) register. The

BVARGAIN (Address 0x439F), CVARGAIN (Address 0x43A1),

DVARGAIN (Address 0x43A3), EVARGAIN (Address 0x43A5),

and FVARGAIN (Address 0x43A7) registers control the reactive

power gain calibration on the B through F current channels,

respectively. The xVARGAIN registers affect the reactive power

in the same way that the xWGAIN registers affect the active power.

Equation 9 shows the relationship between gain adjustment and

the xVARGAIN registers.

Reactive Power = Reactive Power0 ×

⎟

⎠

⎞

⎜

⎝

⎛

+ 1

800000

xVARGAIN

(9)

ENERGY OFFSET CALIBRATION

The ADE7816 includes offset calibration registers for the active

and reactive powers on all six channels. Offsets can exist in the

power calculations due to crosstalk between channels on the

PCB and in the ADE7816. The offset calibration allows these

offsets to be removed to increase the accuracy of the measure-

ment at low input levels.

The active power offset can be corrected on Current Channel A

by adjusting the AWATTOS (Address 0x4392) register. The

BWATTOS (Address 0x4394), CWATTOS (Address 0x4396),

DWATTOS (Address 0x4398), EWATTOS (Address 0x439A),

and FWATTOS (Address 0x439C) registers control the active

power offset calibration on the B through F current channels,

respectively. The xWATTOS registers are 24-bit, signed, twos

complement registers with default values of 0. One LSB in the

active power offset register is equivalent to 1 LSB in the active

power multiplier output. With full-scale current and voltage

inputs, the maximum power output is equal to 1FF6A6B =

33,516,139. At −80 dB down from full scale (active power scaled

down 104 times), one LSB of the xWATTOS registers represents

0.0298%. Equation 10 shows the relationship between the

xWATTOS registers and the active energy reading.

xWATTHR = xWATTHR0 +

(10)

⎟

⎠

⎞

⎜

⎝

⎛

)

(

8000

onTime

Accumulati

xWATTOS

WTHR

Similar offset calibration registers are available for the reactive

power. The reactive power on Current Channel A can be offset

calibrated using the AVAROS (Address 0x439E). The BVAROS

(Address 0x43A0), CVAROS (Address 0x43A2), DVAROS

(Address 0x43A4), EVAROS (Address 0x43A6), and FVAROS

(Address 0x43A8) registers control the reactive power gain

calibration on the B through F current channels, respectively.

The xVAROS registers affect the reactive powers in the same way

that the xWATTOS registers affect the active power. Equation 11

shows the relationship between the xVAROS registers and the

reactive energy reading.

xVARHR = xVARHR0 +

(11)

⎟

⎠

⎞

⎜

⎝

⎛

)

(

8000

onTime

Accumulati

xVAROS

VARTHR

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