71M6511/71M6511H
Single-Phase Energy Meter IC
DATA SHEET
AUGUST 2007
Instantaneous Power Measurement Variables
The FREQSEL Register selects the input phase used for frequency measurement and for the MAIN_EDGE counter. The
frequency measurement is implemented using the frequency locked loop of the CE for the selected phase.
IxSQSUM_X and VxSQSUM are the squared current and voltage samples acquired during the last accumulation interval.
INSQSUM_X can be used for computing the neutral current.
CE
Name
Description
Address
33
RESERVED
Fundamental frequency.
FS
LSB
−6 Hz for MUX_DIV = 1
≡
≈ 0.587 ⋅10
232
41
FREQ_X
FS
or
−6 Hz for MUX_DIV = 2
≈ 0.763⋅10
232
4A
4B
4C
4D
4E
4F
50
I0SQSUM_X
I1SQSUM_X
RESERVED
RESERVED
V0SQSUM_X
RESERVED
RESERVED
The sum of squared current samples from each element.
LSB = 6.6952*10-13 IMAX2 / In_82 A2h (for MUX_DIV = 1)
LSB = 5.1501*10-13 IMAX2 / In_82 A2h (for MUX_DIV = 2)
The sum of squared voltage samples from each element.
LSB= 6.6952*10-13 VMAX2 V2h (for MUX_DIV = 1)
LSB = 5.1501*10-13 VMAX2V2h (for MUX_DIV = 2)
The RMS values can be computed by the MPU from the squared current and voltage samples as per the formulae:
IxSQSUM ⋅ LSB ⋅3600⋅ FS
VxSQSUM ⋅ LSB ⋅3600⋅ FS
=
IxRMS
=
VxRMS
NACC
NACC
Note: FS = 2520.6Hz (MUX_DIV = 1) or 3276.8Hz (MUX_DIV = 2)
Other Measurement Parameters
MAINEDGE_X is useful for implementing a real-time clock based on the input AC signal. MAINEDGE_X is the number of half-
cycles accounted for in the last accumulated interval for the AC signal of the phase specified in the FREQSEL register.
CE
Name
Description
Address
52
53
RESERVED
RESERVED
The number of edge crossings of the selected voltage in the previous
accumulation interval. Edge crossings are either direction and are de-
bounced.
55
MAINEDGE_X
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