I am trying to replicate this circuit:
Taken from AN679 [PDF link here]
I have a question regarding C17 - 0.47 uF. This is the capacitor which drops most of the voltage in the power supply part.
In application note, they have mentioned the voltage to be 630 V. I want to know the minimum safe voltage for the capacitor that I can choose for 220 VAC line (which can go up to 250 V in some cases). The objective is to reduce the size of the components and I feel that I might be able to find smaller capacitors if I go for a lower voltage.
Also, they have taken phase as the reference (GND?) while making the circuit. I know that we are dealing with ac circuit and this doesn't matter but is it a preferred way to do things? Should I invert the connections (phase and neutral entering at points K3 and K4) or leave it like that?