ADE7953 datasheet(17/68 Pages) AD

17 / 68 page

Data Sheet

ADE7953

Rev. A | Page 17 of 68

TERMINOLOGY

Measurement Error

ADC Offset Error

The error associated with the energy measurement made by the

ADE7953 is defined by

Error

Measuremen

(1)

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 dc analog input signal.

The magnitude of the offset depends on the gain and input range

selection. However, the offset is removed from the current and

voltage channels by a high-pass filter (HPF), and the power

calculation is not affected by this offset.

100

−

Energy

True

Energy

True

ADE7953

Registered

Energy

Phase Error Between Channels

The high-pass filter (HPF) and digital integrator introduce a

slight phase mismatch between the current channels and the

voltage channel. The all-digital design ensures that the phase

matching between the current channels and the voltage channel

is within ±0.05° over a range of 45 Hz to 65 Hz. This internal

phase mismatch can be combined with the external phase error

(from current sensor or component tolerance) and calibrated

with the phase calibration registers.

Gain Error

The gain error in the ADCs of the ADE7953 is defined as the

per-channel difference between the measured ADC output code

(minus the offset) and the ideal output code (see the Current

Channel ADCS section and the Voltage Channel ADC section).

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

Power Supply Rejection (PSR)

PSR quantifies the ADE7953 measurement error as a percentage

of reading when the power supplies are varied. For the ac PSR

measurement, a reading at nominal supplies (3.3 V) is taken. A

second reading is obtained with the same input signal levels when

an ac signal (120 mV rms/100 Hz) 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 (3.3 V) is taken. A

second reading is obtained with the same input signal levels when

the power supplies are varied by ±10%. Any error introduced is

again expressed as a percentage of reading.

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