SMPS design

[somanshumehta]

Actually I am designing a 12V to 19.5V dc-dc converter for my notebook.To select among different topologies I need to know the difference between flyback and resonant SMPS?

 

[somanshumehta]

Please also mention about synchronous rectifiers amd why mosfets are used in it?

 

[BobK]

You know you can buy one for less that you could ever build it?

http://www.ebay.com/itm/150W-DC-DC-...209?pt=LH_DefaultDomain_0&hash=item5af2821209

Bob

 

[duke37]

Mosfets are used because they have a very low resistance if turned on fully. A diode will have drop a considerable forward voltage, perhaps 1V.

When rectifying 100V a 1V drop is not too serious (1%). but if rectifying 3V it is a dramatic loss. Schottky diodes are better at low voltages but cannot match a mosfet.