71M6511/71M6511H
Single-Phase Energy Meter IC
DATA SHEET
AUGUST 2007
APPLICATION INFORMATION
Connection of Sensors (CT, Resistive Shunt, Rogowski Coil)
Figure 29 and Figure 30 show how resistive dividers, current transformers, restive shunts, and Rogowski coils are connected
to the voltage and current inputs of the 71M6511.
Vout = R * Iout = R * Iin/N
core
VA = Vin * Rout/(Rout + Rin)
Iin
Iout
Iin
VA
IA
R
Vout
Rin
Vin
Rout
V3P3
1/N
Filter
Iout
Figure 29: Resistive Voltage Divider (left), Current Transformer (right)
Vout = R * Iin
Vout = dIin /dt
Iin
Iin
1/N
IA
IA
R
R
Vout
Vout
VC
V3P3
V3P3
Iin
Figure 30: Resistive Shunt (left), Rogowski Coil (right)
Distinction between 71M6511 and 71M6511H Parts
71M6511H parts go through a process of trimming and characterization during production that make them suitable to high-
accuracy applications.
The first process applied to the 71M6511H is the trimming of the reference voltage, which is guaranteed to have accuracy over
temperature of better that ±10PPM/°C.
The second process applied to the 71M6511H is the characterization of the reference voltage over temperature. The
coefficients for the reference voltage are stored in so-called trim fuses (I/O RAM registers TRIMBGA, TRIMBGB, TRIMM[2:0].
The MPU program can read these trim fuses and calculate the correction coefficients PPM1 and PPM2 per the formulae given
in the Performance Specifications section (VREF, VBIAS). See the Temperature Compensation section for details.
The fuse TRIMBGB is non-zero for the 71M6511H part and zero for the 71M6511 part.
Trim fuse information is not available for non-H parts. Thus, the standard are to be applied. These settings are:
•
•
PPMC = TC1 * 22.46 = –149
PPMC2 = TC2 * 1150.1 = –392
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