71M6541D Datasheet, PDF (131/166 Pages) Maxim Integrated Products – 0.1% Accuracy Over 2000:1 Current Range Energy Meter ICs

71M6541D/F/G and 71M6542F/G Data Sheet
5.3.8.2 Instantaneous Energy Measurement Variables
IxSQSUM_X and VxSQSUM (see Table 87) are the sum of the squared current and voltage samples
acquired during the last accumulation interval.
Table 87: CE Energy Measurement Variables (with Local Sensors)
CE
Address
0x8C
0x8D
0x90
0x91^†
Name
I0SQSUM_X
I1SQSUM_X
V0SQSUM_X
V1SQSUM_X
Description
The sum of squared current samples from each
element.
LSB_I = 9.4045*10^-13 IMAX² A²h
When EQU = 1, I0SQSUM_X is based on IA and
IB.
The sum of squared voltage samples from each
element.
LSB_V= 9.4045*10^-13 VMAX² V²h
Configuration
Figure 35 (page 93)
Figure 37 (page 95)
† _{71M6542 only.}
CE
Address
0x8C
0x8D
0x90
0x91^†
Table 88: CE Energy Measurement Variables (with Remote Sensor)
Name
I0SQSUM_X
I1SQSUM_X
V0SQSUM_X
V1SQSUM_X
Description
The sum of squared current samples from each
element.
LSB_I = 2.55872*10^-12 * IMAX² A²h
When EQU = 1, I0SQSUM_X is based on IA and
IB.
The sum of squared voltage samples from each
element.
LSB_V= 9.40448*10^-13 * VMAX² V²h
Configuration
Figure 36 (page 94)
Figure 38 (page 96)
† _{71M6542 only.}
The RMS values can be computed by the MPU from the squared current and voltage samples as follows:
Ix_RMS =
IxSQSUM ⋅ LSB_I ⋅ 3600 ⋅ F_S
N _ACC
Vx_RMS =
VxSQSUM ⋅ LSB_V ⋅ 3600 ⋅ F_S
N _ACC
Note: N_ACC = SUM_SAMPS[12:0] (CE RAM 0x23).
Other Transfer variables include those available for frequency and phase measurement, and those
reflecting the count of the zero-crossings of the mains voltage and the battery voltage. These transfer
variables are listed in Table 89.
MAINEDGE_X (CE RAM 0x83) reflects the number of half-cycles accounted for in the last accumulated
interval for the AC signal of the phase specified in the FREQSEL[1:0] field in CECONFIG (CE RAM 0x20[7:6]).
MAINEDGE_X is useful for implementing a real-time clock based on the input AC signal.