ade7762 Analog Devices, Inc., ade7762 Datasheet - Page 11

• Manufacturer Part Number: ade7762
• Description: Polyphase Energy Metering Ic With Phase Drop Indication
• Manufacturer: Analog Devices, Inc.

TERMINOLOGY
Measurement Error
The error associated with the energy measurement made by the
ADE7762 is defined by the following formula:
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 between channels, a phase correction network
is placed in the current channel. The phase correction network
ensures a phase match between the current channels and the
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 (see Figure 24 and
Figure 25).
Power Supply Rejection (PSR)
This quantifies the ADE7762 measurement error as a percent-
age of reading when the power supplies are varied.
For the ac PSR measurement, a reading at a nominal supply
(5 V) is taken. A 200 mV rms/100 Hz signal is then introduced
onto the supply, and a second reading is obtained under the
same input signal levels. Any error introduced is expressed as a
percentage of reading. See the definition for Measurement Error.
For the dc PSR measurement, a reading at nominal supplies
(5 V) is taken. The supply is 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 reading.
Percentage Error =
⎛
⎜
⎜
⎝
Energy Reg
istered by
True Energ
ADE7762
y
–
True Energ
y
⎞
⎟
⎟
⎠
×
100
%
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(1)
ADC Offset Error
This 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 an analog input signal offset.
However, because the HPF is always present, the offset is re-
moved from the current channel, and the power calculation
is not affected by this offset.
Gain Error
The gain error of the ADE7762 is defined as the difference
between the measured output frequency (minus the offset)
and the ideal output frequency. The difference is expressed
as a percentage of the ideal frequency. The ideal frequency is
obtained from the ADE7762 transfer function (see the Transfer
Function section).
ADE7762