Datasheet
71M6513/71M6513H
3-Phase Energy Meter IC
DATA SHEET
SEPTEMBER 2011
© 2005-2011 Teridian Semiconductor Corporation Page: 71 of 104
A Maxim Integrated Products Brand
CE
Address
Name Description
0x33 FREQSEL
Selected phase for the frequency monitor, the phase-to-phase voltage
measurements, and voltage zero crossings:
Phase A: 0 (default)
Phase B: 1
Phase C: 2
0x41 FREQ_X
Fundamental frequency. LSB
6
32
10587.0
2
−
⋅≈≡
S
F
Hz
0x4A I0SQSUM_X
The sum of squared current samples from each element.
LSB = 9.4045*10
-13
IMAX
2
/ In_8
2
A
2
h
0x4B I1SQSUM_X
0x4C I2SQSUM_X
0x4D INSQSUM_X
The sum of squared current samples from the calculated neutral:
∑
++
2
210
)( III
.
LSB = 1.2539*10
-12
IMAX
2
/ In_8
2
A
2
h
0x4E
V0SQSUM_X
The sum of squared voltage samples from each element.
LSB= 9.4045*10
-13
VMAX
2
V
2
h
0x4F V1SQSUM_X
0x50 V2SQSUM_X
0x5A V3SQSUM_X
The sum of squared voltage samples from the V3 input. If CAL_V3 =
8192, then LSB = 9.4045*10
-13
VMAX
2
V
2
h or 9.4045*10
-13
IMAX
2
I
2
h
The RMS values can be computed by the MPU from the squared current and voltage samples as per the formulae:
Other Measurement Parameters
PH_AtoB_X and PH_AtoC_X contain phase angle information between the phase voltages, depending on the setting of
FREQ_SEL, as shown in the table below. The phase angle information can be used for phase sequencing and error detection.
If the voltage at the selected phase is missing, the meter accuracy will be reduced.
To maintain accuracy, FREQ_SEL must be set to a phase with an active voltage. For example, in a system where
phase A is lost (which can be detected using the SAG bits or by comparing the voltage VA with a lower limit),
FREQ_SEL must be set to an alternative phase to maintain accuracy.
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 FREQ_SEL register.
ACC
S
RMS
N
FLSBVxSQSUM
Vx
⋅⋅⋅
=
3600
ACC
S
RMS
N
FLSBIxSQSUM
Ix
⋅⋅⋅
=
3600