ADE7755ARSZ View Datasheet(PDF) - Analog Devices

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ADE7755ARSZ

Energy Metering IC with Pulse Output

Analog Devices 

TERMINOLOGY

Measurement Error

The error associated with the energy measurement made by the

ADE7755 is defined by the following formula:

PercentageError =

Energy Registered by the ADE7755 − True Energy ×100%

True Energy

Phase Error Between Channels

The high-pass filter (HPF) in Channel 1 has a phase lead response.

To offset this phase response and equalize the phase response

between channels, a phase compensation network is also placed

in Channel 1. The phase compensation network matches the

phase to within ±0.1° over a range of 45 Hz to 65 Hz and ±0.2°

over a range of 40 Hz to 1 kHz. See Figure 30 and Figure 31.

Power Supply Rejection (PSR)

The PSR quantifies the ADE7755 measurement error as a

percentage of the reading when the power supplies are varied.

For the ac PSR measurement, a reading at nominal supplies

(5 V) is taken. A 200 mV rms/100 Hz signal is then introduced

onto the supplies and a second reading is obtained under the

same input signal levels. Any error introduced is expressed as a

percentage of the reading (see the Measurement Error definition).

For the dc PSR measurement, a reading at nominal supplies

(5 V) is taken. The supplies are then varied ±5% and a second

reading is obtained with the same input signal levels. Any error

introduced is again expressed as a percentage of the reading.

ADE7755

ADC Offset Error

The ADC offset error refers to the dc offset associated with the

analog inputs to the ADCs. It means that with the analog inputs

connected to AGND, the ADCs still see a small dc signal

(offset). The offset decreases with increasing gain in Channel 1.

This specification is measured at a gain of 1. At a gain of 16, the

dc offset is typically less than 1 mV. However, when the HPF is

switched on, the offset is removed from the current channel,

and the power calculation is not affected by this offset.

Gain Error

The gain error of the ADE7755 is defined as the difference between

the measured output frequency (minus the offset) and the ideal

output frequency. It is measured with a gain of 1 in Channel 1.

The difference is expressed as a percentage of the ideal frequency.

The ideal frequency is obtained from the ADE7755 transfer

function (see the Transfer Function section).

Gain Error Match

The gain error match is defined as the gain error (minus the

offset) obtained when switching between a gain of 1 and a gain

of 2, 8, or 16. It is expressed as a percentage of the output frequency

obtained under a gain of 1. This gives the gain error observed

when the gain selection is changed from 1 to 2, 8, or 16.

Rev. A | Page 11 of 20

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