I've carefully read Wikipedia article and can't get one important thing – is there galvanic separation in such supply?
The diagram in that article goes like this:
What I see here is that the transformer is only on one path and there's the "output->chopper controller" path that bypasses the transformer. Usually the transformer is the unit that performs galvanic separation.
Does this mean a switched-mode power supply doesn't feature galvanic separation between the input and the output? Is it possible for unlimited current to flow through the power supply?
Best Answer
Not all SMPSs provide galvanic separation. DC/DC converters transforming between two low voltages in a circuit often don't. The block diagram, however, shows a mains connected SMPS, and most of those do have galvanic separation.
The feedback often goes via an opto-coupler, which indeed is missing in the article's block diagram. The signal is PWM, so a normal (digital output) opto-coupler can be used.