I've read a lot about calibration in this forum and in the data sheets and application notes. For example, the AN-1076 proposes two methods: accurate source method and reference meter method. But it's funny because if you choose the second one, it states:
To calibrate the current and voltage rms, use the accurate source method. See the Current and Voltage RMS Calibration section for additional information.
So, at the end, there is only a suitable method, according to the application note.
What I'd like to do is to use a reference meter for all the process, selecting three points:
- Zero load, with no voltage or current applied to the circuit.
- Known resistive load, using the mains power as power source, with some PF=1 loads.
- Known inductive load, using the mains power as power source, with some PF<1 loads.
I guess this method could characterize the chip + circuit deviations in terms of gain and offset, but I have doubts on how to save that information in the calibration registers.
For example, is the zero load Vrms reading somehow related to the xVRMSOS register value?