Solid caps vs electrostatic caps (computer psu)

[budm]

Re: Solid caps vs electrostatic caps (computer psu)

But aren't those 5V, 3.3 are minor rails low current not the 3.3V heavy current output?
http://home.coolpc.com.tw/fb/FSP/HEX...XA-HA550-3.jpg
So if I look at it correctly, the combined 3.3V and 5 output power is 100W so then what you will have left is 450W for the 12V?
I can see pro and con in that design.

[Per Hansson]

Re: Solid caps vs electrostatic caps (computer psu)

It's basically a requirement for handling the low power states of Haswell CPU's and later. (C6 & C7).
Group regulated PSU's can't handle such a load.

Pretty much all modern ATX power supplies use DC-DC conversion for the 3.3v and 5v.
Of course you need to "upsize" the 12v to compensate for it.

[budm]

Re: Solid caps vs electrostatic caps (computer psu)

Con: the power dissipation of the rectifier for that 12V will be pretty high.
Do they implement the Synchronous Rectification some how to help reduce the power loss?

[Per Hansson]

Re: Solid caps vs electrostatic caps (computer psu)

AFAIK all ATX supplies with 80+ Platinum and higher rating have DC-DC designs for the minor rails.
And they all also employ Synchronous Rectification, I think the Seasonic X series was first on the market with it in 2009.
I honestly don't think it's possible to design a true 80+ Platinum PSU with full range input without it.

So that speaks in favor that the efficiency loss is extremely minor.
Remember that you can design a DC-DC module with very close to 100% efficiency.
But the same can't be done with a AC>DC conversion (or wise versa)

Also remember that while there is some loss in DC-DC conversion there is also loss in the coils required for a group regulated unit.

[Stefan Payne]

Re: Solid caps vs electrostatic caps (computer psu)

AFAIK all ATX supplies with 80+ Platinum and higher rating have DC-DC designs for the minor rails.

Nope, there's one exception, Antec Earthwatts Platinum.

Its even most 80plus Gold units have DC-DC, I only know of the FSP Aurum Plattform that isn't DC-DC...