I wonder how do the electronics device manufacturing companies log and plot the power consumption plot by time. I would think they sample both voltage and current simultaneously and multiply these two.
But if the data loggers are measuring voltages one needs to add a low value series resistor across the main Vcc line from the supply. But is special way of current to voltage conversion used to measure the current?
This is how I would do it:
Imagine DUT above is a low power device and it consumes power not constant way. And we want to leave it for a day connected to a power supply Vs and log voltage and current data it draws to plot the daily power consumption plot.
So the data acquisition can be done by sampling two channels simultaneously where (Vch1-Vch2)/Rs would give us the current data and Vch2 would give us the voltage data. So the power would be:
P = |(Vch1-Vch2)/Rs| * Vch2
Is that how companies make such a test during prototyping and verification procedure?