Datasheet

71M6511/71M6511H
Single-Phase Energy Meter IC
DATA SHEET
NOVEMBER 2010
Page: 69 of 98 © 2005–2010 Teridian Semiconductor Corporation V2.7
A Maxim Integrated Products Brand
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
Address
Name Description
33 RESERVED
41 FREQ_X
Fundamental frequency.
LSB
6
32
10587.
0
2
−
⋅≈≡
S
F
Hz for MUX_DIV = 1
or
6
32
10763.0
2
−
⋅≈
S
F
Hz for MUX_DIV = 2
4A I0SQSUM_X
The sum of squared current samples from each element.
LSB = 6.6952*10
-13
IMAX
2
/ In_8
2
A
2
h (for MUX_DIV = 1)
LSB = 5.1501*10
-13
IMAX
2
/ In_8
2
A
2
h (for MUX_DIV = 2)
4B I1SQSUM_X
4C RESERVED
4D RESERVED
4E V0SQSUM_X
The sum of squared voltage samples from each element.
LSB= 6.6952*10
-13
VMAX
2
V
2
h (for MUX_DIV = 1)
LSB = 5.1501*10
-13
VMAX
2
V
2
h (for MUX_DIV = 2)
4F RESERVED
50 RESERVED
The RMS values can be computed by the MPU from the squared current and voltage samples as per the formulae:
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
Address
Name Description
52 RESERVED
53 RESERVED
55 MAINEDGE_X
The number of edge crossings of the selected voltage in the previous
accumulation interval. Edge crossings are either direction and are de-
bounced.
ACC
S
RMS
N
FLSBVxSQSUM
Vx
⋅⋅⋅
=
3600
ACC
S
RMS
N
FLSBIxSQSUM
Ix
⋅⋅⋅
=
3600