Maxim Integrated 71M6541 Demo Board - Manual (Page 30)

71M6541 Demo Board REV 3.0 User’s Manual
30 Rev 4.0
1.10.3 LSB VALUES IN CE REGISTERS
Table 1-8: CE Registers and Associated LSB Values
Register Name LSB Value Comment
W0SUM_X 1.55124*10 -12 *IMAX*VMAX
The real energy for element 1 (IA, VA), measured in Wh per accumu-
lation interval
VAR0SUM_X 1.55124*10 -12 *IMAX*VMAX
The reactive energy for element 1 (IA, VA), measured in VARh per
accumulation interval
W1SUM_X 1.55124*10 -12 *IMAX*VMAX
The real energy for element 2 (IB, VA), measured in Wh per accumu-
lation interval
VAR1SUM_X 1.55124*10 -12 *IMAX*VMAX
The reactive energy for element 2 (IB, VA), measured in VARh per
accumulation interval
I0SQSUM_X 2.55872*10 -12 *IMAX*VMAX
The sum of squared current samples in element 1 (IA). This value is
the basis for the I
RMS
calculation performed in the MPU.
I1SQSUM_X 2.5587*10
-12
*IMAX*VMAX
The sum of squared current samples in element 2 (IB). This value is
the basis for the I
RMS
calculation performed in the MPU.
V0SQSUM_X 9.40448*10 -13 *IMAX*VMAX The sum of squared voltage samples in element 1 (VA).
V1SQSUM_X 9.40448*10 -13 *IMAX*VMAX
The sum of squared voltage samples in element 1 (VA). This value is
not used for EQU 0 or EQU 1.
1.10.4 CALCULATING IMAX AND KH
The relationship between the resistance of the shunt resistors and the system variable IMAX is determined by
the type of Remote Sensor Interface used, and is as follows:
IMAX = 0.044194 / R
S
for the 71M6601
IMAX = 0.012627 / R
S
for the 71M6201
Where:
R
S
= Shunt resistance in
Ω
Table 1-9 shows IMAX values resulting from possible combinations of the shunt resistance value and the type
of 71M6X0X Remote Sensor Interface used for the application. All values are for PRE_E = 0 (I/O RAM register
2704 = 0x90), PULSE_FAST = 0, and PULSE_SLOW = 0. The CE register at address 0x30 has to be adjusted
as shown in the rightmost column of the table.