71M6521DE Datasheet, PDF (60/107 Pages) Teridian Semiconductor Corporation – Energy Meter IC

71M6521DE/DH/FE Data Sheet
APPLICATION INFORMATION
Connection of Sensors (CT, Resistive Shunt)
Figure 28 and Figure 29 show how resistive dividers, current transformers, and restive shunts are connected to the
voltage and current inputs of the 71M6521DE/DH/FE.
VA = Vin * R_out/(R_out + R_in)
VA
V_in
R_in
R_out
Figure 28: Resistive Voltage Divider (Left), Current Transformer (Right)
Figure 29: Resistive Shunt
Distinction between 71M6521DE/71M6521FE and 71M6521DH Parts
The 71M6521DH (high-accuracy) part go through an additional process of characterization during production which
makes them suitable to high-accuracy performance over temperature.
The first process, applied to all parts is the trimming of the reference voltage to the target value of 1.195 V.
The second process, which is applied only to the high-accuracy parts, is the characterization of the reference voltage
over temperature. The coefficients for the reference voltage are stored in trim fuses (I/O RAM registers TRIMBGA,
TRIMBGB, TRIMM[2:0]. The MPU can read these trim fuses and calculate the correction coefficients PPM1 and
PPMC2 per the formulae given in VREF, VBIAS section. See Temperature Compensation section for additional
details.
The fuse TRIMBGB is non-zero for the high-accuracy parts and zero for the regular parts.
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