ADE7761A datasheet(8/24 Pages) AD

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ADE7761A

Rev. 0 | Page 8 of 24

TERMINOLOGY

Measurement Error

The error associated with the energy measurement made by the

ADE7761A is defined by

⎟

⎠

⎞

⎜

⎝

⎛

−

100

Energy

True

Energy

True

ADE7761A

registered

Energy

Error

Percentage

Phase Error Between Channels

The high-pass filter (HPF) in the current channel has a phase

lead response. To offset this phase response and equalize the

phase response among channels, a phase correction network is

also placed in the current channel. The phase correction network

ensures a phase match between the current channels and

voltage channels 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.

Power Supply Rejection (PSR)

PSR quantifies the ADE7761A measurement error as a

percentage of reading when the power supplies are varied. For

the ac PSR measurement, a reading at nominal supplies (5 V) is

taken. A second reading is obtained with the same input signal

levels when an ac (175 mV rms/100 Hz) signal is introduced

onto the supplies. Any error introduced by this ac signal is

expressed as a percentage of reading (see the Measurement

Error definition).

For the dc PSR measurement, a reading at nominal supplies

(5 V) is taken. A second reading is obtained with the same input

signal levels when the power supplies are varied ±5%. Any error

introduced is again expressed as a percentage of reading.

ADC Offset Error

The dc offset associated with the analog inputs to the ADCs.

With the analog inputs connected to AGND, the ADCs still see

a dc analog input signal. The magnitude of the offset depends on

the input gain and range selection (see the Typical Performance

Characteristics section). However, when HPFs are switched on,

the offset is removed from the current channels and the power

calculation is not affected by this offset.

Gain Error

The gain error in the ADE7761A ADCs 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 V1A. The difference is expressed as a

percentage of the ideal frequency, which is obtained from the

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 or 16. It is

expressed as a percentage of the output ADC code obtained

under a gain of 1.

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