The MSP430F673x(A) family has up to three independent sigma delta data converters. For a single phase system at least two ΣΔs are necessary to independently measure one voltage and current. The code accompanying this application report addresses the metrology for a 1-phase system with limited discussion to anti-tampering, however, the code supports the measurement of the neutral current. The clock to the SD24 (f_M ) is derived from the DCO running at 16 MHz. The sampling frequency is defined as $f_s=\frac{f_m}{OSR}$ , the OSR is chosen to be 256 and the modulation frequency, f_M, is chosen as 1 MHz (1 048 576 Hz), resulting in a sampling frequency of 4.096 ksps. The SD24s are configured to generate regular interrupts every sampling instant.

The following are the ΣΔ channels associations:

• SD0P0 and SD0N0 → Voltage V1
• SD1P0 and SD1N0 → Current I1
• SD2P0 and SD2N0 → Current IN (Neutral)