Cirrus Logic CS5480 - Manual (Page 20)

CS5480
20 DS980F3
These offsets can be either positive or negative,
indicating crosstalk coupling either in phase or out of
phase with the applied voltage input. The power offset
registers can compensate for either condition.
To use this feature, measure the average power at no
load. Take the measured result (from the P1
AVG
(P2
AVG
) register), invert (negate) the value, and write it
to the associated average active power offset register,
P1
OFF
(P2
OFF
).
4.10 Average Reactive Power Offset
The average reactive power offset registers, Q1
OFF
(Q2
OFF
), can be used to offset erroneous power
sources resident in the system not originating from the
power line. Residual reactive power offsets are usually
caused by crosstalk into current channels from voltage
channels, or from ripple on the meter’s or chip’s power
supply, or from inductance from a nearby transformer.
These offsets can be either positive or negative,
depending on the phase angle between the crosstalk
coupling and the applied voltage. The reactive power
offset registers can compensate for either condition. To
use this feature, measure the average reactive power at
no load. Take the measured result from the
Q1
AVG
(Q2
AVG
) register, invert (negate) the value and
write it to the associated reactive power offset register,
Q1
OFF
(Q2
OFF
).