Cirrus Logic CS5461A - Manual (Page 14)

CS5461A
14 DS661F3
To generate a value for the accumulated active energy
over the last computation cycle, the active power can be
multiplied by the time duration of the computation cycle.
The apparent power is the combination of the active
power and reactive power, without reference to an im-
pedance phase angle, and is calculated by the
CS5461A using the following formula:
The apparent power is registered once every computa-
tion cycle.
4.4 Linearity Performance
The linearity of the V
RMS
, I
RMS
, and active power mea-
surements (before calibration) will be within ±0.1% of
reading over the ranges specified, with respect to the in-
put voltage levels required to cause full-scale readings
in the I
RMS
and V
RMS
registers. Refer to Linearity Per-
formance Specifications on page 7.
Until the CS5461A is calibrated, the accuracy of the
CS5461A (with respect to a reference line-voltage and
line-current level on the power mains) is not guaranteed
to within ±0.1%. See
Section 7. System Calibration on
page 35. The accuracy of the internal calculations can
often be improved by selecting a value for the Cycle
Count Register that will cause the time duration of one
computation cycle to be equal to (or very close to) a
whole-number of power-line cycles (and N must be
greater than or equal to 4000).
S V
RMS
I
RMS
 =