71M6511 Datasheet, PDF (68/95 Pages) Teridian Semiconductor Corporation – Single-Phase Energy Meter IC

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
Address
33
41
4A
4B
4C
4D
4E
4F
50
Name
RESERVED
FREQ_X
I0SQSUM_X
I1SQSUM_X
RESERVED
RESERVED
V0SQSUM_X
RESERVED
RESERVED
Description
Fundamental frequency.
LSB
≡
F_S
2 ³²
≈ 0.587 ⋅10 ^−6 Hz for MUX_DIV = 1
or
F_S
2 ³²
≈ 0.763 ⋅10^−6 Hz for MUX_DIV = 2
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:
Ix_RMS =
IxSQSUM ⋅ LSB ⋅3600 ⋅ F_S
N _ACC
Vx_RMS =
VxSQSUM ⋅ LSB ⋅3600 ⋅ F_S
N _ACC
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
52
53
55
Name
RESERVED
RESERVED
MAINEDGE_X
Description
The number of edge crossings of the selected voltage in the previous
accumulation interval. Edge crossings are either direction and are de-
bounced.
Page: 68 of 95
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