Switching Regulator Topologies used in Contemporary PSUs

According to the peak current that will pass from the main switches, the desired efficiency levels, the maximum operating voltage across the switches the cost etc. a manufacturer has several switching regulator topologies at his disposal.

Below you will find a table that compares several switching regulator topologies (Marty Brown: Power Supply Cookbook)

Lately, many PSUs use the LLC resonant topology. This topology, utilizing a resonant combination of inductors and capacitors, shapes the voltage and current waveforms in switching MOSFETs allowing for soft (zero voltage) switching which by its turn leads to RFI and EMI reduction and minimized switching losses, so we gain increased efficiency. Utilizing LLC resonant converters higher switching speeds along with efficiencies of 93 – 95% can be achieved.

Finally, here you will find a very informative pdf file that describes many commonly used topologies.