71M6543F/H and 71M6543G/GH Data Sheet
measurement error. The 71M6543H and 71M6543GH 0.1% grade devices should be used in Class
0.2% and Class 0.5% designs, to allow margin for the other error sources in the system.
The preceding discussion in this section also applies to the71M6603 (0.5%), 71M6113 (0.5%) and
71M6203 (0.1%) remote sensors. Refer to the 71M6xxx Data Sheet for details.
4.5.2 Temperature Coefficients for the 71M6543F and 71M6543G
The equations provided below for calculating TC1 and TC2 apply to the 71M6543F and 71M6543G (0.5%
energy accuracy). In order to obtain TC1 and TC2, the MPU reads TRIMT[7:0] (I/O RAM 0x2309) and uses
the TC1 and TC2 equations provided. PPMC and PPMC2 are then calculated from TC1 and TC2, as shown.
The resulting tracking of the reference voltage (VREF) is within ±40 ppm/°C, corresponding to a ±0.5%
energy measurement accuracy. See 4.5.1 Distinction Between Standard and High-Precision Parts.
TC1(µV /°C) = 275 − 4.95⋅TRIMT
TC2(µV /°C2) = −0.557 + 0.00028⋅TRIMT
PPMC = 22.4632⋅TC1
PPMC2 =1150.116⋅TC2
See 4.5.5 and 4.5.6 below for further temperature compensation details.
4.5.3 Temperature Coefficients for the 71M6543H and 71M6543GH
The 71M6543H and 71M6543GH undergo a two-pass factory trimming process which stores additional
trim fuse values. The additional trim fuse values characterize the device’s VREF behavior at various
temperatures. The values for TC1 and TC2 are calculated from the values read from the TRIMT[7:0] (I/O
RAM 0x2309), TRIMBGB[15:0] (Info Page 0x92 and 0x93) and TRIMBGD[7:0] (Info Page 0x94) non-
volatile on-chip fuses using the equations provided. The resulting tracking of the reference voltage is
within ±10 ppm/°C, corresponding to a ±0.126% energy measurement accuracy. The equations for deriving
PPCM and PPMC2 from TC1 and TC2 are also provided. See 4.5.1 Distinction Between Standard and
High-Precision Parts.
(
)
TC1(µV/℃)=35.091+0.01764∙TRIMT+1.587∙ 푇푅퐼푀퐵퐺퐵 − 푇푅퐼푀퐵퐺퐷
TC2(µV /°C2) = −0.557 − 0.00028⋅TRIMT
PPMC = 22.4632⋅TC1
PPMC2 =1150.116⋅TC2
TRIMT[7:0] trims the VREF voltage for minimum variation with temperature. The TRIMT[7:0] fuses are
read by the MPU directly at I/O RAM address 0x2309[7:0].
During the second pass trim for the 71M6543H and 71M6543GH, VREF is further characterized at 85°C
and 22°C, and the resulting fuse trim values are stored in TRIMBGB[15:0] and TRIMBGD[7:0],
respectively. TRIMBGB[15:0] and TRIMBGD[7:0] cannot be read directly by the MPU. See 5.3 Reading
the Info Page (71M6543H and 71M6543GH only) on page 118 for information on how to read the Info
Page trim fuses.
See 4.5.5 and 4.5.6 below for further temperature compensation details.
4.5.4 Temperature Coefficients for the 71M6xx3
Refer to the 71M6xxx Data sheet for the equations that are applicable to each 71M6xx3 part number and
the corresponding temperature coefficients.
4.5.5 Temperature Compensation for VREF and Shunt Sensors
This section discusses metrology temperature compensation for the meter designs where current shunt
sensors are used in conjunction with Teridian’s 71M6xx3 remote isolated sensors, as shown in Figure 31.
Sensors that are directly connected to the 71M6543 are affected by the voltage variation in the 71M6543
VREF due to temperature. On the other hand, shunt sensors that are connected to 71M6xx3 remote
sensor are affected by the VREF in the 71M6xx3. The VREF in both the 71M6543 and 71M6xx3 can be
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