12v to 5v usb multi port

[Ranger14]

I want to build a dc-dc converter that can supply 5v 2amps to say 4 or 6 usb ports.. What would be the best way ?? I am a noob and trying to work out the best way . Also would it be better to make separate circuit per usb port or combine some ???Oh I want to build not buy if possible..
Thanks

[prawncrackers]

id think its easy to use a dedicated buck converter IC for this

this one is really famous but the is also a bit old
http://www.ti.com/lit/ds/symlink/lm2596.pdf

ive had a lot of wireless routers that have that IC converting 12v or 5v down to 3.3v or somewhere.
i guess it would be easier just to just wire all the ports to one supply but i think you want to make each of them separate from the other so that a circuit fault in one port will not affect the others...

build a working circuit first then lets explore the protection thing.