I'm trying to understand and tweak this smartplug reference design from TI. I'm stumped on the Metrology Analog Filters section on page 1. What I do not understand is why is there a 0R resistor on the Neutral line and more importantly why is this line grounded?
Also since the shunt method is inherently unsafe, can I simply replace the shunt with the primary of the current transformer? In the attached schematic the current source and the terminating resistor essentially mimic the secondary of a current transformer. If I can replace the shunt, can I simply do away with the instrumentation amp in the reference schematic and simply put the attached bit in and feed the signal to the MCU?