PC DC-to-DC Power Supply

[Delivereath]

Hello,

I'm looking to build a kind of power supply for a low consumption computer. The voltage source will be a 15V DC supply. Total power output would be 60 or 80W with 4 voltage outputs (+12V, +5V, +3.3V and -12V). I've been looking for step-down converters but I don't know which ones I should try.

Has anyone any advice about which kind of step-down converter I should buy ? The main goal is to create a complete ATX 2.2 power supply.

Thanks in advance.

 

[blueroomelectronics]

Have you looked into Mini-ITX DC power supplies? Some run off 12VDC to 18VDC.

 

[crutschow]

For good efficiency you need switching power converters.

Do you want to build your own or buy modules?

 

[Delivereath]

I want to build my own supply. I've already checked existing DC power supply for Mini-ITX computers but I'm more interested in the project of doing it myself.

I've seen some step-down converters that could be used (like MAX8548). However these components have a single output. This means that I would 4 different step-down converters. Do you know any way to use only one switching component and 4 MOSFET/coils stages ? Or do I really need 4 integrated step-down converters ?

 

[crutschow]

For proper voltage regulation, each output needs it's own control circuit, so typically you do use 4 separate step-down converters. The -12V unit needs to invert the input polarity also, of course.

 

[Delivereath]

Thanks for your reply.

I've found an IC that should match what I'm looking for :

**broken link removed**

Vin from 3 to 28V, Vout from 0.6 to 25V and max output current of 15A.

I will use one of those for each positive output (12V, 5V and 3.3V).

However I'm still missing the way to create the -12V output. I've found some switching inverters but I only need a small current on this line (less than 0.5 amps).

Is there an easier solution ?

Thanks in advance