ADE5166 datasheet(47/148 Pages) AD

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Preliminary Technical Data

ADE5166/ADE5169/ADE5566/ADE5569

Rev. PrB | Page 47 of 148

Calibration Concerns

Typically, when a meter is being calibrated, the voltage and

current circuits are separated, as shown in Figure 27. This

means that current passes through only the phase or neutral

circuit. Figure 27 shows current being passed through the phase

circuit. This is the preferred option because the ADE5166/

ADE5169 start billing on the input IPA on power-up. The phase

circuit CT is connected to IPA in the diagram. Because the

current sensors are not perfectly matched, it is important to

match current inputs. The ADE5166/ADE5169 provide a gain

calibration register for IPB, IBGAIN (Address 0x1C). IBGAIN is

a 12-bit, signed, twos complement register that provides a gain

resolution of 0.0244%/LSB.

For calibration, a first measurement should be done on IPA by

setting the SEL_I_CH bits to 0b01 in the CALMODE register

(0x3D). This measurement should be compared to the measure-

ment on IPB. Measuring IPB can be forced by setting the SEL_I_CH

bits to 0b10 in the CALMODE register (0x3D). The gain error

between these two measurements can be evaluated using

()

( )

()

Measuremen

Error

−

The two channels IPA and IPB can then be matched by writing

–Error(%)/(1 + Error(%)) × 212 to the IBGAIN register. This

matching adjustment is valid for all energy measurements made

by the ADE5166/ADE5169., including active power, reactive

power, Irms, and apparent power,

AGND

IPA

IPB

TEST

CURRENT

240V rms

Figure 27. Fault Conditions for Inactive Input Greater Than Active Input

di/dt CURRENT SENSOR AND DIGITAL

INTEGRATOR FOR THE ADE5569/ADE5169

A di/dt sensor, a feature available for the AD5569/ADE5169 but

not for the AD5566/ADE5166, detects changes in the magnetic

field caused by ac currents. Figure 28 shows the principle of a

di/dt current sensor.

MAGNETIC FIELD CREATED BY CURRENT

(DIRECTLY PROPORTIONAL TO CURRENT)

+ EMF (ELECTROMOTIVE FORCE)

– INDUCED BY CHANGES IN

MAGNETIC FLUX DENSITY (di/dt)

Figure 28. Principle of a di/dt Current Sensor

The flux density of a magnetic field induced by a current is directly

proportional to the magnitude of the current. The changes in

the magnetic flux density passing through a conductor loop

generate an electromotive force (EMF) between the two ends of

the loop. The EMF is a voltage signal that is proportional to the

di/dt of the current. The voltage output from the di/dt current

sensor is determined by the mutual inductance between the

current-carrying conductor and the di/dt sensor. The current

signal needs to be recovered from the di/dt signal before it can

be used. An integrator is therefore necessary to restore the

signal to its original form.

The ADE5569/ADE5169 have a built-in digital integrator to

recover the current signal from the di/dt sensor. The digital

integrator on the current channel is switched off by default when

the ADE5569/ADE5169 are powered up. Setting the INTE bit in

the MODE1 register (0x0B) turns on the integrator. Figure 29 to

Figure 32 show the gain and phase response of the digital

integrator.

FREQUENCY (Hz)

–10

–20

–30

–40

–50

100

1000

Figure 29. Combined Gain Response of the Digital Integrator and

Phase Compensator

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